Digest for sci.electronics.repair@googlegroups.com - 3 updates in 2 topics

9:40 AM Penedão 0 comments
Stu jaxon <stankowalski02@gmail.com>: Sep 30 03:51AM -0700

I have Vizio led tv, model #D43-C1, no picture, no sound, no back light, power light comes on, then fades away, any help will be appreciated..??
John-Del <ohger1s@gmail.com>: Sep 29 12:57PM -0700

On Tuesday, September 29, 2020 at 6:48:26 AM UTC-4, Stu jaxon wrote:
> Hi Group, can someone help please? Im working on a Vizio led tv, D43-C1 Power Supply / LED Board 715g6973 p02-002-00h. when testing the output pins to main logic board with dmm, i get 5v on stby, 18v on 6 pins that the legend aks for 12v, when i disconnect the harness to the main board, i get zero volts on stby and 18v on the 12v pins.. when testin the k18a60v mosfet Q9102, on the drain pin I get 18v dc.. should i change the power supply board or the mosfet..?
 
The legends on Vizio boards often don't match reality. Also, are you sure you are using hot ground (PFC cap) when making your measurements on the MosFet?
Stu jaxon <stankowalski02@gmail.com>: Sep 29 03:23PM -0700

> On Tuesday, September 29, 2020 at 6:48:26 AM UTC-4, Stu jaxon wrote:
> > Hi Group, can someone help please? Im working on a Vizio led tv, D43-C1 Power Supply / LED Board 715g6973 p02-002-00h. when testing the output pins to main logic board with dmm, i get 5v on stby, 18v on 6 pins that the legend aks for 12v, when i disconnect the harness to the main board, i get zero volts on stby and 18v on the 12v pins.. when testin the k18a60v mosfet Q9102, on the drain pin I get 18v dc.. should i change the power supply board or the mosfet..?
> The legends on Vizio boards often don't match reality. Also, are you sure you are using hot ground (PFC cap) when making your measurements on the MosFet?
 
yep, same results, 18v??
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Digest for sci.electronics.repair@googlegroups.com - 5 updates in 4 topics

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jaugustine@verizon.net: Sep 29 07:31AM -0400

Hi,
 
I recently bought a 2017 Jeep Grand Cherokee Trail Hawk.
 
I found light settings where you can turn off Daylight Running Lights,
Wiper (when it rains) Lights, when you lock you vehicle, but there is
NO setting to disable headlights turning on when you open the door.
 
Any ideas?
 
Thank You in advance, John
"pfjw@aol.com" <peterwieck33@gmail.com>: Sep 29 04:52AM -0700

There is a relay under the hood for that - but it puts your entire system on "manual". I believe it is marked DRL - but it does vary by model.
 
Peter Wieck
Melrose Park, PA
Stu jaxon <stankowalski02@gmail.com>: Sep 29 03:48AM -0700

Hi Group, can someone help please? Im working on a Vizio led tv, D43-C1 Power Supply / LED Board 715g6973 p02-002-00h. when testing the output pins to main logic board with dmm, i get 5v on stby, 18v on 6 pins that the legend aks for 12v, when i disconnect the harness to the main board, i get zero volts on stby and 18v on the 12v pins.. when testin the k18a60v mosfet Q9102, on the drain pin I get 18v dc.. should i change the power supply board or the mosfet..?
Tom Kupp <tjkupp@gmail.com>: Sep 28 04:53PM -0400

On 09/27/20 11:38, Tom Kupp wrote:
 
>> Peter Wieck
>> Melrose Park, PA
 
> Thanks; I have submitted a question.
Here is the reply:
 
Hello,
 
Thank you for contacting us and sorry for reply you so late.
 
Please be informed CNet 5614XE this product has been phased out for a
long time, and we didn't find its spec information in our database, so
we are sorry that we can't help you on this issue.
 
Again, we are sorry for the inconvenience made and please don't hesitate
to contact us if any other questions. Thank you.
 
Best regards,
 
CNet support
"Ron D." <ron.dozier@gmail.com>: Sep 28 12:32PM -0700

terrell. Nic
 
At the university where I worked, they had a ground potential across about 200' in their computing center built duting the big mainframe ERA. A motor-generator fed the building.
 
During a storm, there was a potential that developed across the ground between one side and the other side of the building. They had to replace those lines with fiber.
 
The rotor is an Eagle Aspen ROTR-100 which is pretty cool, but going to be repairable if it fails. min uses a coax for power/positioning. You can, but I didn't use it for the antenna feed too. You can even use it to power a pre-amp.
it send DISEQ/C signals on the coax for positioning.
 
One bad thing is that the readout is not real-time when the antenna is moving. The readout "pretends" to know where the antenna is.
 
I did use a thrust bearing which isn't available anymore and I did replace the studs with stainless studs. 318 SS and anti-sieze if possible. All hardware went that route. The antenna mount is an eve mount made with Unistrut and I guy every 120 degrees using a non-conductive guy wire called Phillystran. I never got a chance to replace the aluminum mast wth fiberglass,
 
When we had the tree trimmed, I offered to help take down the antenna. To do that, I install a 2 piece shaft collar under the antenna and loosen the antenna and remove the connections. The tree guy in the bucket truck just plucked the antenna off the mast. He did his thing and plopped it back on the mast and I could finish it after the install. I had to do some more important antenna stuff and I was unable to change the mast to fiberglass.
 
I changed all of the U-bolts to stainless too. I didn't powdercoat the rotor brackets although I had plenty of time if i had planned it during the original install.
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Digest for sci.electronics.repair@googlegroups.com - 5 updates in 3 topics

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"jurb...@gmail.com" <jurb6006@gmail.com>: Sep 28 06:21AM -0700

Weird ? I had one that howled from feedback anytime the reverb was on.
 
The solution ? I reversed the speaker wires.
"Ron D." <ron.dozier@gmail.com>: Sep 27 11:46AM -0700

Measurements: The CM-7777 has only one input. I used an OTA signal, not on the same day.
I measured before the pre-amp one day and after the power injector (about 30') on another day. Cable is copper clad RG6QS. Measured with a Sencore SLM1453i http://salestores.com/sencor01.html. These measurements were done before the re-assignment of channels.
 
The measurement is problematic because of 1) Tilt and 2) different days.
 
"Evaluation of a Winegard HD8200U Antenna
with a Channel Master CM-7777 30 dB mast mounted Preamp"
FM trap is enabled in the antenna pre-amp.
May 2019
Voltages in Columns C and F are in dBuV
Gain is just Column F minus Column C



@antenna (N3) @In Attic (N4) Gain(N5)
2 53.6 73.5 19.9
3 42.4 58.0 15.6
4 47.5 67.5 20.0
5 29.9 54.1 24.2
6 59.5 80.6 21.1
7 Fail 37.4 Fail
8 16.1 Fail 41.6 Fail
9 22 Fail 38.1 Fail
10 * * 46.5 Fail
11 * 39.4 Fail
12 36.7 58.4 21.7
13 * * 35.0 Fail
14 * * 28.5 Fail
15 * * 29.2 Fail
16 * * 31.6 Fail
17 * * N5 49.2
18 * * 27.7 Fail
19 * * 39.5 Fail
20 * * 28.9 Fail
21 27.6 Fail 27.6
22 43.4 63.6 20.2
23 * * 25.9 Fail
24 * * 28.4 Fail
25 * * 34.3 Fail
26 32.2 55.2 23.0
27 * * 29.2 Fail
28 * * 27.6 Fail
29 * * 25.8 Fail
30 * * 26.8 Fail
31 21.2 48.7 27.5
32 32.3 56.7 24.4
33 * * 30.1 Fail
34 34.4 * 56.0 21.6
35 * * 27.4
36 * * 30.2
37 * * 30.7
38 * * 39.0
39 * * 28.7
40 * * 33.1
41 * * N1 31.2
42 U U N6 55.5
43 * * 31.3
44 U U N7
Missed a few here,

"I think the reason for the * @antenna is that the Sencore didn't find anything
Using 8VSB modulation. Not sure."
 
TVFool data from Highest to lowest NF
6 (6.1) ABC NM: 42.6db Pwr -48.2dbm 2Edge, 28.8 miles
...
42 (29.1) Fox NM: 21.5 Pwr: -69.4 2Edge, 28.9 miles
 

On one TV using a converter box, it shows 29/100 for signal strength on it's internal meter for 29.1 and 91 for channel 6.1. This includes another amp at 35 feet (unknown gain) from the 7777, then 65 feet to a 2-way splitter and about 35' to the TV.
 
The "stupid" Samsung "Smart TV" only shows s/n ratio. I do have a "tuner" that will
show both in real units.
 
The system is/will be:
Mast amp (currently CM-7777, plan to change to a Kitz lower NF amplifier)
30'; RG-6QS copper clad
Power injector in attic
Variable 0-18db gain amplifier using an attenuator
65'; RG-6QS copper clad to basement; About 40' to each TV location (some less, some more)
 
Currently: A 2-way splitter to two TV's about 40' away.
 
Planned:
Blonder Tongue BIDA 75-43a (30-45 db Gain with tilt compensation cards and variable) that replaces a Tin Lee amplifier
four 24 db 4-way taps to 12 locations (existing, but not currently used because of a broken amplifier)
Locations are around 40' away.
 
The gain is unknown because the AMP and attenuator WAS prior to the 2-way splitter and it was recently moved to the attic as is. performance is definitely better.
 
My main distribution amp died and I'm planning to replace it with a Blonder-tongue BID 75a-43 for 12 locations fed by four 4-way 24 db taps.
 
This has available various "tilt cards", but might consider a custom VHF attenuator. I think the CM-7777 might overload with cellular signals.
 
Why copper clad? Friends that were in the satellite TV industry gave me 1000 feet.
Ralph Mowery <rmowery28146@earthlink.net>: Sep 27 04:46PM -0400

In article <5ac1d4c4-3a0b-4602-9ff1-4df219d352c6n@googlegroups.com>,
ron.dozier@gmail.com says...
 
> My main distribution amp died and I'm planning to replace it with a Blonder-tongue BID 75a-43 for 12 locations fed by four 4-way 24 db taps.
 
> This has available various "tilt cards", but might consider a custom VHF attenuator. I think the CM-7777 might overload with cellular signals.
 
> Why copper clad? Friends that were in the satellite TV industry gave me 1000 feet.
 
The day and time of day can make much difference. I monitored a ham
repeater all the time that is about 40 miles away by air. It normally
showed a 3 on a scale of 0 to 10. Some days there were no signal (about
two or three times a month), and about the same number of times it
pinned the meter on the high side. That was on 220 MHz.
 
There is very little loss in the copper clad cable (as long as the
copper is not broken or missing) at TV frequencies due to the skin
effect compaired to solid copper. If there was much loss it would not
be used. The iron core does make for a stiff center pin for the
connection.
 
The S/N is really more important that the signal strength. You may be
boosting the noise along with the signal and the TV will not be able to
decode the signal.
Michael Terrell <terrell.michael.a@gmail.com>: Sep 27 05:28PM -0700

On Saturday, September 26, 2020 at 11:14:26 PM UTC-4, Jeff Liebermann wrote:
> Note that this is lithium based and not white-lithium grease.
 
> Please note that very little of this has much to do with a receive
> only TV antenna, rotor, and mast/tower.
 
I haven't seen one used in decades. I think that it was an article in the late '60s that recommended it. Some really cheap TV rotors used sleeve bearings, that corroded. Pot metal against brass with crap lube didn't last very long. OTOH, the old Alliance rotors often had a crumbling rubber top seal that let water into the housings. I rebuilt a lot of those that were already 30 years old. A new seal, a new run cap and new control cable put them back into service.
 
A direct strike would vaporize that strap, but if it was a lesser hit, it would help. I had a CATV tower hit once. The audio wiring at the site was unsheilded. The EMP from the high current pulse fried the aural inputs of every modulator. Nothing was done right when the site was built. The tower was well grounded, with three concrete pours that went 60' into the ground for the self supporting tower, but the lines from the tower entered the building without ground blocks. The equipment used the building's neutral for grounding. They had punched holes in the ceiling tiles to run cable all over the place. I had to replace the RCA CA3240 ICs in every modulator, then I rewired the site. Ground rods under the equipment racks. A 19" relay panel was used to make a grounding plate for all the Coax entering or leaving the building. Large Panduit wire duct ran from the Microwave racks to the equipment racks. The idiot manager tried to tell me that there was no way to hold the wires in it, with the bottom open. A case of pencils solved that. Insert them, one per foot. Run the cables. Snap on the covers and remove the pencils if you want to. We never had another problem indoors, but we did lose some coax coming down the tower. A 1400 pound Ch4 antenna was at the top, to pick up a distant TV station. Rather than rip out all the underground cable to replace it, it left the tower about 50 feet up, and sloped to the roof of the building to allow plenty of room for big trucks to pass underneath.
 
As a Broadcast engineer, I've seen more than one tower take a direct strike. It plays hell with the power lines for the tower lights. The stations are too cheap to use a transformer for isolation at the tower base, so the wires have to be repaired quite often. The tallest tower I've worked at was 1700' with two TV stations, five FM stations a Motorola Trunking system and a bunch of government radios on it in North Central Florida.
crazy chicken <craziestchicken2007@gmail.com>: Sep 27 05:27PM -0700

Thank you so much! I will tell you if any of this works! If it does, anyone else that comes into the google group will see your message and leave!
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Digest for sci.electronics.repair@googlegroups.com - 6 updates in 2 topics

9:40 AM Penedão 0 comments
Jeff Liebermann <jeffl@cruzio.com>: Sep 26 05:05PM -0700

On Fri, 25 Sep 2020 12:36:44 -0700 (PDT), "Ron D."
 
>Antenna is pretty big, A Winegard HD-8200U and the CM-7777 antenna mounted amp.
<https://winegard.com/products/hdtv-digital-antennas/hdtv-antenna-amplifiers/boost/hd8200u-platinum-hd-series-antenna>
<https://www.channelmaster.com/TV_Antenna_Preamplifier_p/cm-7777v3.htm>
 
Unless you're dealing with weak signals and fringe coverage, a
high gain (26dB in this case) amp is an invitation to overload
problems. Quoting the Channelmaster data sheet:
The Titan 2 High Gain Preamplifier is recommended for
professional installers only. Due to the high gain output
of this product, it can result in over amplification if
not used in the appropriate scenario. Over amplification
can cause issues with the television tuner's ability to
receive and display some or all channels.
Note that there were 3 radically different versions of the CM-7777
amplifier. Which version do you have?
 
<https://photos.imageevent.com/holl_ands/files/ota//CM7777%20Ckt%20Brd%20Rear%20Photo%20-%20damaged%20rlongfield.jpg>
The original Titan 2 amp had a phenolic PCB. V2 had separate
VHF and UHF outputs, while V3 has them combined into one output.
Therefore, my guess is that it's a V2.
 
>but they were not done at the same time. I measures the signal
>at the antenna and the NEXT day the signal after the power
>injector (about 30')
 
Are you trying to measure amplifier gain using an OTA (over the air)
signal? The amplifier gain is not the same for the VHF and UHF
sections. It's also has some intentional "tilt" in the frequency
response intended to compensate for the higher coax cable losses
at the higher UHF channels.
 
>Gain varied from 15.6 (physical channel 3) and 27.1 for channel 21.
>I'm at least 30 miles outside of Philly and aimed toward Philly
>stations.
 
Due to intentional "tilt" in the frequency response, that's too much
"tilt" for the amplifier. CH3 = 60 MHz, CH21 = 512 MHz.
Cable loss for 100ft of RG-6/u is 1.6dB at 60 Mhz and 5.2dB at
512 MHz. Therefore, I would expect to see a corresponding:
5.2 - 1.6 = 3.6dB
difference in gain between CH21 and CH3.
Comparing with your measurement:
27.1 - 15.6 = 11.8dB
Yep, way too much "tilt" in your measurement. Do it again, this time
with a spectrum analyzer and an RF sweep generator.
 
>The rotor also has a bypass braid around it which many people
>forget.
 
What is a bypass braid? I've never heard of the term. Neither
has Google search. Do you mean something like quad shielded
RG-6/u?
 
>A large tree is going to hit by lightning first.
 
Large height or large girth?
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Ralph Mowery <rmowery28146@earthlink.net>: Sep 26 08:13PM -0400

In article <sljvmflff4bfi51udegldlovgb03cg13s5@4ax.com>,
jeffl@cruzio.com says...
 
> >A large tree is going to hit by lightning first.
 
> Large height or large girth?
 
Bypass braid for a rotator is for lightning protection. You put a piece
of wire to the mast above the rotator and then to the mast below the
rotator. That is suppose to make a good connection from the top mast to
the bottom mast.
 
It is not so much the actual gain of the amplifiers, but the noise
figure. If just feeding one or two tv sets all the gain needs to be is
just to make up for the loss of the feedline if the amp is very near the
antenna and a little more depending on the noise figure of the TV set.
If the amp is near the TV, it needs very little gain (maybe 10 db) and
better have a noise figure much lower than the TV tuner.
 
Hopefully a tall tree will get hit first,but no guarentee.
Michael Terrell <terrell.michael.a@gmail.com>: Sep 26 05:21PM -0700

> What is a bypass braid? I've never heard of the term.
 
It was a piece of heavy braid to connect the upper mast to the lower mast for grounding. It was supposed to prevent lightning or static discharges from damaging the ball bearings or their races. The grease wasn't conductive, and would harden into an insulating layer of varnish. That forced the downlead to carry the discharge current.
Jeff Liebermann <jeffl@cruzio.com>: Sep 26 08:14PM -0700

On Sat, 26 Sep 2020 17:21:21 -0700 (PDT), Michael Terrell
>to the lower mast for grounding. It was supposed to prevent
>lightning or static discharges from damaging the ball
>bearings or their races.
 
Thanks. Even with the magic buzzwords, I wasn't able to find any
rotator or tower installation instructions that involved such a bypass
braid. I don't think it will do much to prevent 20,000 Amps from
turning a big antenna rotator into a metal recycling candidate. I
double if it will do much to prevent arcing from pitting the bearings.
The are a large number of bearings in the rotator and it only take a
decent connection through one bearing to discharge a static
electricity buildup. I've taken apart a few rotators and found plenty
of rust, considerable loss of grease, but no pitting (except from the
rust).
 
The bypass wire might also protect against an unusual situation where
a ham operator uses a tower or mast as both a monopole antenna and a
rotator mount. In transmit, the RF current will go through the
rotator bearings. That's not a problem if the rotator is not in
motion, but potentially a big problem if the bearings are moving,
arcing merrily as they roll along. To be fair, I haven't proven that
this is happening, but I'm fairly certain it could easily be tested.
 
>The grease wasn't conductive, and would harden into an insulating
>layer of varnish. That forced the downlead to carry the discharge current.
 
I've seen grease turned to varnish, usually in salty marine
atmospheres or after using the wrong type of grease to lubricate the
rotator. I sometimes find some water in the bearing race. In my
never humble opinion, what's happening is the grease is getting washed
away by rain, fog and condensation. The idea grease would be
something that can (in order of most important to least important):
1. Will not wash out (i.e. marine grade grease).
2. Inhibits galvanic corrosion and rust formation.
3. Does no "foam" or create abscesses that collect water.
4. Slightly conductive to discharge static electricity.
5. Tolerates high temperatures by NOT evaporating or dripping.
6. Handles a heavy load.
What I've been using are various marine lithium based grease
concoctions such as WD-40 Specialist Marine-Grade Grease:
<https://www.amazon.com/WD-40-Specialist-Marine-Grade-Resistant-Grease/dp/B071R943VS/>
<https://www.wd40.com/products/water-resistant-grease/>
Note that this is lithium based and not white-lithium grease.
 
Please note that very little of this has much to do with a receive
only TV antenna, rotator, and mast/tower.
 
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Jeff Liebermann <jeffl@cruzio.com>: Sep 26 08:35PM -0700

On Sat, 26 Sep 2020 20:13:15 -0400, Ralph Mowery
 
>> >A large tree is going to hit by lightning first.
 
>> Large height or large girth?
 
>Bypass braid for a rotator is for lightning protection.
 
Methinks it has more to do with discharging a static electricity
buildup (St Elmo's Fire) than protecting against a lightning hit or
lightning induced current.
 
>of wire to the mast above the rotator and then to the mast below the
>rotator. That is suppose to make a good connection from the top mast to
>the bottom mast.
 
Well, I've never seen such a thing, never had anyone request it, and
couldn't find with Google any installation instructions recommending
such a practice.
 
>antenna and a little more depending on the noise figure of the TV set.
>If the amp is near the TV, it needs very little gain (maybe 10 db) and
>better have a noise figure much lower than the TV tuner.
 
Agreed. I think I mumbled something about too much gain causing
intermod problems further up this thread. Another problem is loss of
dynamic range when the added gain also raises the noise floor but not
changing the overload point. Way back in the dark ages of TV, the
receivers were stone deaf and any kind of RF preamplifier offered a
performance improvement. These days, with GaAs low noise front ends,
the best that a preamp can offer is to compensate for coax cable
losses.
 
>Hopefully a tall tree will get hit first,but no guarentee.
 
We don't get much lightning here on the left coast[1]. I live in a
forest full of 100ft and higher trees. I know of three local trees
(out of millions) that were hit by lightning in the past 40 odd years.
Both were in rather odd locations, such as the bottom of a canyon or
surrounded by taller trees. My best guess is the tree holding the
most water has the highest conductivity and therefore gets hit first.
 
 
[1] Mother nature delivered our accumulated savings (with interest)
of lightning on Aug 15, 2020, with a really impressive display of
flashing lights, and starting 500+ big fires that are currently trying
to incinerate California, Oregon, and Washington states. 5 million
acres burned and climbing.
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Guy Patterson <str00ntz@aol.com>: Sep 26 10:14AM -0700

On Friday, September 25, 2020 at 10:02:18 PM UTC-4, crazy chicken wrote:
> I am having the exact same problem. What is broken, the VCR or VHS that is making it B&W. Is everything B&W because my VHS tapes are too old and have eroded? I have tapes since 1990, so do they still work 30 years later? Is there no solution to this problem? I am trying to get my tapes to digital, and I need to solve this problem.
> Thanks for reading!
> - A Chicken
 
A specific model number would be helpful. I may still have service records somewhere on VCRs. But no, the age of the tape has nothing to do with a loss of chroma in playback assuming the signal to noise ratio is still respectable (viewable image without severe noise). The chroma sub carrier won't degrade any faster than any other part of the composite waveform will.
 
Old VCRs suffer the same issues as modern garbage does: lazy electrolytic caps as they age. If you only need this to run long enough to do a digital transfer, try taking the cover off the VCR and heating the innards for about 10 minutes with a hair dryer (don't use a real heat gun). With a good hot soak, a weak electro cap can increase it's value and lower it's ESR enough to allow the color to work as it should. If it responds to heat, make all your transfers while it stays hot.
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Digest for sci.electronics.repair@googlegroups.com - 15 updates in 7 topics

9:40 AM Penedão 0 comments
Tom Kupp <tjkupp@gmail.com>: Sep 18 10:34AM -0400

I've had this for a long time, but haven't used it for 5 years. Somehow
the ac adapter and whatever literature there was have disappeared. Can
anybody tell me the DC voltage and current specs?
danny burstein <dannyb@panix.com>: Sep 18 03:53PM


>I've had this for a long time, but haven't used it for 5 years. Somehow
>the ac adapter and whatever literature there was have disappeared. Can
>anybody tell me the DC voltage and current specs?
 
There's a realistic chance that if you get out
a magnifying glass and hold the unit at an angle
to the light, that you'll see, in teensy raised
print, the numbers you're looking for.
 
 
--
_____________________________________________________
Knowledge may be power, but communications is the key
dannyb@panix.com
[to foil spammers, my address has been double rot-13 encoded]
Tom Kupp <tjkupp@gmail.com>: Sep 22 10:22AM -0400

On 09/18/20 11:53, danny burstein wrote:
> a magnifying glass and hold the unit at an angle
> to the light, that you'll see, in teensy raised
> print, the numbers you're looking for.
 
No joy, just says POWER.
Tom Kupp <tjkupp@gmail.com>: Sep 27 11:38AM -0400


> Submit a question. Can't hurt, might help. Otherwise, back into what is needed as others have advised.
 
> Peter Wieck
> Melrose Park, PA
 
Thanks; I have submitted a question.
crazy chicken <craziestchicken2007@gmail.com>: Sep 25 07:02PM -0700

I am having the exact same problem. What is broken, the VCR or VHS that is making it B&W. Is everything B&W because my VHS tapes are too old and have eroded? I have tapes since 1990, so do they still work 30 years later? Is there no solution to this problem? I am trying to get my tapes to digital, and I need to solve this problem.
Thanks for reading!
- A Chicken
dplatt@coop.radagast.org (Dave Platt): Sep 25 09:54PM -0700

In article <0e80f69b-170d-4252-9982-7405105d3484n@googlegroups.com>,
>because my VHS tapes are too old and have eroded? I have tapes since 1990, so do they still work 30 years
>later? Is there no solution to this problem? I am trying to get my tapes to digital, and I need to solve this
>problem.
 
https://www.broadcaststore.com/pdf/model/793700/TT198%20-%204802.pdf
has some useful information about how VHS color recording works,
although the details of the testing procedure it suggests won't help
you all that much.
 
With tapes in good condition, and a VCR in good condition and
alignment, color playback should work OK. It's unlikely that several
different tapes would have degraded in the same way, so the fault is
more probably with the VCR.
 
VHS can lose color because of dirty or bad playback heads in the drum,
or because of a fault in the color-conversion circuits (VHS stores the
color information in a different frequency band than is used by NTSC
video). A failed 3.68 MHz color-reference oscillator would be one
such possible fault, and I'm sure there are plenty of others.
 
Sure, there's a solution: try a different VCR, preferably one which is
in known-good condition.
 
Your existing VCR might be repairable; it might need something as
simple as a good professional cleaning (and I don't mean a "cleaning
tape", I mean a by-hand cleaning by a technician who knows how to do
it properly and who won't damage the heads) or it might need circuitry
repairs. Old VHS players are common enough that simply buying a
(used) replacement is likely to be cheaper than a repair.
 
Another possibility - if you have hooked your VCR up to a TV/monitor
using an S-video cable, try a different cable. S-Video sends the
luminance (brightness) signal on one wire, and the chroma (color)
signal on another wire. A broken wire or pin could cut off the chroma
and leave you seeing black-and-white. See if the problem is still
there if you use a composite-video cable (RCA plug/jack, usually
yellow) rather than S-Video.
 
If you're trying to video-capture onto a PC, you might have a problem
with your video-capture card.
amdx <amdx@knology.net>: Sep 25 01:00PM -0500

On 9/25/2020 10:50 AM, Jeff Liebermann wrote:
> <http://www.ambery.com/rfmp-w50.html>
> Dimension: 498mm (W) x 360mm (D) x 280mm (H)
> Or, perhaps you mean't something other than size?
 
 I stored a rack mount Wingard distribution amplifier for years before
I tossed it.
 
I was about 19" x 6" x 3".
 
I always thought it would be good for something, but never ran across
that something.
 
                                         Mikek
 
 
 
 
 
 
 
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
"Ron D." <ron.dozier@gmail.com>: Sep 25 12:36PM -0700

jeff:
 
Antenna is pretty big, A Winegard HD-8200U and the CM-7777 antenna mounted amp.
 
The reason why I don;t TRUST is I did gain measurements using a Sencore 8VSB tester. My gain measurements were not consistant, but they were not done at the same time. I measures the signal at the antenna and the NEXT day the signal after the power injector (about 30')
 
Gain varied from 15.6 (physical channel 3) and 27.1 for channel 21. I'm at least 30 miles outside of Philly and aimed toward Philly stations.
 
The rotor also has a bypass braid around it which many people forget. A large tree is going to hit by lightning first.
David Farber <farberbear.unspam@aol.com>: Sep 20 03:36PM -0700

This Carvin B2000 bass amplifier was brought to me with the problem that
it wouldn't turn on. The user said it was working fine until there was a
bright flash that could be seen through the front grill. Then it went
dead. I opened it up and found a very fried and crispy looking disc
which I think is an MOV. It's labeled TR1 on the "main board close up"
as seen in these pictures. You can see by the photo it parallels the
(removed) relay's normally open contact (AC out?) and the common, AC in
contact.
Photos are here, https://app.box.com/s/ch670hnsrtoswqhebtrye95n2vw5ktre
 
The other photos are to give you a general idea of what the board looks
like. The reason I took photos of the entire board is that Carvin's own
website, https://carvinaudio.com/pages/bass-amp-schematics shows
different versions of the B2000 schematic but none of them matches what
I see in the version I'm trying to troubleshoot. There is one vacuum
tube in the unit, a 12AX7.
 
After cutting out the MOV, and then powering it up, the power relays
would not engage. The other issue is that when I pulled out one of the
two power relays for inspection of its discolored contacts after it
failed to power up, one of the pins came out of its coil. There is no
writing on the relay and its physical construction doesn't look at all
familiar to any relays I've ever seen. I need to replace it assuming the
unit is worth fixing.
 
Does anyone have a schematic for this amp? There is a description of the
amp here:
https://carvinaudio.com/pages/archive-carvin-b2000-lightweight-mono-block-2050w-bass-amp-head
 
The owner said it was purchased around 2000. It looks in good shape for
being 20 years old. According to this report,
https://www.thetonerooms.com/threads/carvin-amps-out-of-business.3035/
Carvin went of business in 2017.
 
Thanks for your replies.
--
David Farber
Los Osos, CA
David Farber <farberbear.unspam@aol.com>: Sep 20 10:17PM -0700

On 9/20/2020 8:06 PM, Phil Allison wrote:
 
Hi Phil. I think I'll try using one of my audio, 8 ohm, 25 watt dummy
load resistors to test it. I'll also put a 200 watt light bulb in series
with the Variac just in case. If there's no overload, then I may as well
pull out the other identical inrush relay and see if I can figure out
what voltage and current it takes to close the contacts. Any idea what
voltage and current rating those contacts need to be?
 
Thanks for your reply.
--
David Farber
Los Osos, CA
legg <legg@nospam.magma.ca>: Sep 21 09:46AM -0400

On Sun, 20 Sep 2020 22:17:29 -0700, David Farber
>pull out the other identical inrush relay and see if I can figure out
>what voltage and current it takes to close the contacts. Any idea what
>voltage and current rating those contacts need to be?
 
It's a fairly common form used in HVAC switching, but more easily
obtained with a plastic dust cap. The open air parts are seldom
used outside of self enclosed fan-free environments, for obvious
reasons.
 
You may have a relay on both input (inrush limiting) and output
(click and pop supression).
 
You'll need to establish what the supply voltage is for the coils.
 
Check for Panasonic JTV or TEconnect T9AS1D series SPST NO.
 
RL
Peabody <waybackNO584SPAM44@yahoo.com>: Sep 20 03:54PM -0500

> to replace (except you'll have to identify them, and
> match to modern available parts, and pay shipping for
> onesies...).
 
I removed all of the electrolytics, and all but one tested
good on my scope. I replaced the dubious one, but the flash
still doesn't work. The oscillator whine doesn't start up.
 
But I did find one thing that gets really hot when the power
switch is turned on. It is a pair of three-pin parts
(triange pattern footprint) that look like cylinders, and
they are enclsed in a U-shaped heatsink. They are each
marked with the Mitsubishi triagle logo, and "B324ST", with
"12" on the second line. I assume they are transistors or
thyristors, but searching for them comes up with nothing.
This is all from the 1980s, so I guess it's not surprising
that the parts aren't active anymore, but it would be nice
to at least find a datasheet.
 
By the way, the dubious cap was right next to the mystery
pair.
 
Any ideas?
 
https://www.eevblog.com/forum/repair/repair-vivitar-3500-speedlight/?
action=dlattach;attach=1070818;image
Peabody <waybackNO584SPAM44@yahoo.com>: Sep 20 04:06PM -0500

Someone on the EEVblog forum says the part number is actually 2SB324, which
is a germanium PNP transistor. I'd guess I won't find a direct replacement
for that.
Bradley Bowman <bradleybowman89@gmail.com>: Sep 19 12:03AM

Hi guys, first time posting to a newsgroup, been lurking for a few weeks
though.
 
I'm attempting to repair a Bose Acoustimass 9 for a customer; I'd already
fixed the display on his LifeStyle 5 CD player and the amp in the
subwoofer appears non-
working. I tested the sub with a signal generator, and the satellite
speakers as well, so I've got the power board, the (rather large)
transformer, and the main amp board to mess with.
 
I've found the 10-page schematic for this system via a Google search, but
the Bose manual for the LifeStyle 5 system was very informative, wondering
if anybody has the one for the Acoustimass amp portion?
 
Thanks,
Brad
JC <Chipbee40_SpamNo@yahoo.com>: Sep 17 02:05PM -0400

> This helps a little.
> thank you very much!
 
Translation in case you need it:
 
https://flic.kr/p/2jHx61m
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Digest for sci.electronics.repair@googlegroups.com - 9 updates in 3 topics

9:40 AM Penedão 0 comments
dplatt@coop.radagast.org (Dave Platt): Sep 24 01:41PM -0700

In article <56unmfhd8j3h69650rfhu107426r70pj2n@4ax.com>,
 
>Masthead amps make good targets for lightning hits. I've seen a few
>where every semiconductor in the amp was fried.
 
Yeah... probably need to consider them to be a potentially-sacrificial
component.
 
The really troublesome ones I've heard/read about, are the
cheapies... sometimes using just a single broadband transistor as a
gain element. Some of these have been known to break into
oscillation, for some reason (or no reason) and blast broadband noise
all over the place.
 
https://www.gpsworld.com/the-hunt-rfi/#:~:text=Reports%20of%20other%20GPS%20users,narrow%20harbor%20entrance%20in%20fog.
 
talks about one such case, in which several on-shipboard "active TV
antenna" systems were emitting enough RF crud to blank out GPS
reception in the harbor in Moss Landing, CA. Not a good thing to lose
your GPS when you're trying to come into a foggy harbor at night.
 
This is one reason why which buying a well-tested, professional-grade
mast-head amplifier would probably be a better idea than buying a
generic cheapie.
Jeff Liebermann <jeffl@cruzio.com>: Sep 24 09:35PM -0700

On Thu, 24 Sep 2020 13:41:43 -0700, dplatt@coop.radagast.org (Dave
Platt) wrote:
 
>>where every semiconductor in the amp was fried.
 
>Yeah... probably need to consider them to be a potentially-sacrificial
>component.
 
I had one mounted on a redwood tree. It wasn't hit by lightning.
Instead, it was invaded by ants, dripping formic acid, which ate the
copper traces on the PCB. I was prepared to replace all the active
components, but not the entire amplifier.
 
>oscillation, for some reason (or no reason) and blast broadband noise
>all over the place.
 
>https://www.gpsworld.com/the-hunt-rfi/#:~:text=Reports%20of%20other%20GPS%20users,narrow%20harbor%20entrance%20in%20fog.
 
This might fill in a few details:
<http://www.learnbydestroying.com/jeffl/GPS%20Jamming%20Moss%20Landing/>
Note the photo of the antenna. The cloverleaf pattern is NOT a
broadband device and will not present a 75 ohm impedance to the
amplifier input. Designing a broadband amplifier to be
unconditionally stable and provide a low NF (noise figure) as well as
high gain into such an antenna is difficult. There will be some
frequency, where the antenna presents the perfect impedance to cause
the amplifier to oscillate. Also, such an antenna construction is not
very tolerant of the corrosive effects of a marine environment and
probably should have been potted or conformal coated.
 
>talks about one such case, in which several on-shipboard "active TV
>antenna" systems were emitting enough RF crud to blank out GPS
>reception in the harbor in Moss Landing, CA.
 
Yep. That happened near me. Although I knew some of the
participants, I didn't know that there had been a transmitter hunt
until two years after it was over and the article appeared in GSP
World.
 
>Not a good thing to lose
>your GPS when you're trying to come into a foggy harbor at night.
 
GPS selective availability was finally turned off on May 1, 2000,
navigating a 150 ft wide harbor entrance channel by GPS would have
been theoretically possible. At the time, MBARI did operate their own
DGPS transmitter on Mt Toro, but that was for precision vessel and
buoy location in the bay. Today, even with WAAS, GALILEO and GLONAS
satellites added to improve GPS precision, I'm told it's still tricky
due to reflections from moving metal masts and rigging, plus a very
large steel building at the power plant. Once into the channel, I
would probably switch to navigating by the harbor lights:
<https://geographic.org/nautical_charts/map_img/18685_3-t.png>
 
>This is one reason why which buying a well-tested, professional-grade
>mast-head amplifier would probably be a better idea than buying a
>generic cheapie.
 
Yep. In my never humble opinion, there was probably nothing wrong
with the amplifier. Instead, it was the design of the antenna, which
had the misfortune of not being properly matched to the RF amplifier
causing the amp to oscillate. A properly designed Yagi, Bow-Tie,
LPDA (log periodic dipole array), or other broadband design, would
worked better, and not oscillated.
<http://www.hdtvprimer.com/ANTENNAS/comparing.html>
<http://www.hdtvprimer.com/SIMS/>
 
 
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Chris K-Man <thekmanrocks@gmail.com>: Sep 25 01:15AM -0700

On Tuesday, September 22, 2020 at 4:54:39 PM UTC-4, Stu jaxon wrote:
> Hi Group, can someone help please, I have an antenna booster
that requires a power supply of 6v 100ma, can i use a variable power
supply 6v 300ma???
 
> Thanks,
____________
 
My idea of a "booster" or "signal amp" is a bigger/higher gain antenna.
 
As far as language differences are concerned, England and India are
forever bound by their use of English. Compared to them, what is spoken
in the States is called AMERICAN: a rebellious corruption and bastardisation
of what is spoken/written in the two aforementioned nations.
 
Where else do you hear "nucular" routinely substitute for nuclear? Or
plural's of item's succeeded with an apostrphe s? LOL!
Jeff Liebermann <jeffl@cruzio.com>: Sep 25 08:50AM -0700

On Fri, 25 Sep 2020 01:15:02 -0700 (PDT), Chris K-Man
 
>My idea of a "booster" or "signal amp" is a bigger/higher gain antenna.
 
Do you mean that a "bigger" box is your idea of a better TV antenna
amplifier? This looks plenty big:
<http://www.ambery.com/rfmp-w50.html>
Dimension: 498mm (W) x 360mm (D) x 280mm (H)
Or, perhaps you mean't something other than size?
 
Higher gain does not buy you much in the way of a performance
improvment. At best, all you need for gain is a bit more than the
coax cable loss between the amp and the TV (or distribution amp). Too
much gain just generates intermodulation products, AGC overload, and
other receiver problems caused by too much signal.
 
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
David Farber <farberbear.unspam@aol.com>: Sep 24 04:38PM -0700

On 9/20/2020 10:40 PM, Phil Allison wrote:
 
> ** 20A at 120VAC at least.
 
> .... Phil
 
Before I went to the trouble of dismantling my audio dummy load resistor
setup, I found two, 3.3 ohm, 1 watt resistors, put them in series, and
soldered them in place of the thermistor. (My supply of resistors in the
low ohm, high power range is almost nil.) I know you said to use at
least a 5 watt resistor but I wanted to get some idea of what kind of
current the amp would draw on power up. I did put a 200 watt lamp in
series. By the time the line voltage was up to 50 ACV, the lamp was
glowing at about half strength and the AC current was about 1 amp. The
voltage across the resistors was over 3 volts so they were already
overloading. At that point I aborted the test. If I do repeat this test
with the 8 ohm, audio, 25 watt dummy load resistor, should I leave the
light bulb in series? Would it take more than 2 amps of continuous AC
power even when bringing up the voltage slowly? What if I bypass the
relay contacts and eliminate the resistors? There shouldn't be any
inrush surge while bringing the voltage up slowly, right?
 
I should also mention that the power amp has a 25 amp line fuse inside.
Does that sound reasonable? Neither the schematic nor the PC board
indicate what the fuse rating should be.
 
Thanks for your reply.
--
David Farber
Los Osos, CA
Phil Allison <pallison49@gmail.com>: Sep 24 08:18PM -0700

David Farber wrote
==================:
> least a 5 watt resistor but I wanted to get some idea of what kind of
> current the amp would draw on power up. I did put a 200 watt lamp in
> series.
 
** Completely spoils the test.
 
 
> By the time the line voltage was up to 50 ACV, the lamp was
> glowing at about half strength and the AC current was about 1 amp.
 
** So nearly 50V AC was across the 200W lamp.
 
Odds are very high the PSU is a dead short to the AC supply - though the bridge rectifier may be OK. Check that and some FETs with a multimeter on diode tests.
 
 
 
.... Phil
David Farber <farberbear.unspam@aol.com>: Sep 24 09:56PM -0700

On 9/24/2020 8:18 PM, Phil Allison wrote:
 
> Odds are very high the PSU is a dead short to the AC supply - though the bridge rectifier may be OK. Check that and some FETs with a multimeter on diode tests.
 
> .... Phil
 
I will recheck for shorts in the PSU.
 
Thanks for your reply.
--
David Farber
Los Osos, CA
Eli the Bearded <*@eli.users.panix.com>: Sep 25 12:00AM

> https://stackoverflow.com/questions/3075130/what-is-the-difference-between-and-regular-expressions
 
I would have guessed he was asking about keyboard keys not working, not
regular expressions.
 
https://www.wikihow.com/Fix-Sticky-Keyboard-Keys
 
> The internet is your friend.
 
Is it? That same internet that foments conspiracy theories like
mushrooms after a rain and gives nobodies who would be ignored shouting
from a street corner rapt audiences?
 
The internet is powerful, but not friendly.
 
Elijah
------
advice on replacing the keyswitches would require more information
Jeff Liebermann <jeffl@cruzio.com>: Sep 24 09:45PM -0700

On Wed, 23 Sep 2020 14:05:38 -0700 (PDT), Robert Long
 
>I'm confused. When I program my unit it tell me to ?*?. What keys do I hit. Or better yet, what is ?*?
 
Sounds like a questions involving military hardware. 56th Artillery
is US Army, but your email address suggests Marine Corp.

?*? is what a printer or display would produce if it doesn't
recognize some characters. In the case, the "?" is a place
holder for a character that can't be displayed or printed.
My guess(tm) is that it's something like "*" where the two
quote marks were replaced by the question marks. On an
Apple computer, they would be replaced by square black boxes.
So, the single key that you press (not hit) is just an asterisk
or an *.
 
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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