Digest for sci.electronics.repair@googlegroups.com - 25 updates in 5 topics

"Mark Zacharias" <mark_zacharias@sbcglobal.net>: Dec 18 07:01AM -0600

Ever get a unit torn down completely to replace a part and discover you had
ordered a 'similar but different" part instead of the correct one?
 
Or grabbed the wrong unit off the shelf, tore it down only to discover you'd
ordered the part for the other (almost identical looking) unit nearby?
 
Yup. Did that yesterday, and it wasn't pretty. I'd ordered a complete main
board (sheet of boards actually) for a Yamaha RX-A1040 because the outputs
etc weren't available and it was under warranty, so it was agreed that I
should order the whole magilla.
 
Unfortunately I tore down an RX-A2010 before the mistake was discovered.
 
At least the only thing lost was the hour or so it took to put that one back
together and commence the repair on the correct unit.
 
Not my finest moment...
 
 
Mark Z.
jurb6006@gmail.com: Dec 18 08:43AM -0800

Another thing is knowing which part is the old one.
 
I have been known to use used parts. So I got this RPTV needs a HV block. (thing that distributes the HV to the three CRTs and divides down the focus and G2 voltages)
 
The wires go all over the place so it takes a little time to get it out and in. So I get it out. Then I picked up the same part and put it back in.
 
I keep track of the used parts pretty well. This one came from a working unit that had weak CRTs. Took a little head scratching but it finally dawned on me that I had reinstalled the bad part.
 
Now, when I know a part is bad I do something to it. Cut off a wire of something. Anything to distinguish it.
 
If it had been a new part, no problem, but these two had about the same amount of dust on them and were pretty much identical.
x@nospam.com: Dec 17 05:05PM -0800

So what is a recommended UPS based on lack of repair experience?
Say around 1000W and say around $150 new.
 
--- news://freenews.netfront.net/ - complaints: news@netfront.net ---
Jeff Liebermann <jeffl@cruzio.com>: Dec 17 05:43PM -0800


>So what is a recommended UPS based on lack of repair experience?
>Say around 1000W and say around $150 new.
 
1000 watts for $150 might be difficult. Something like this should be
close to your target price:
<http://www.harborfreight.com/engines-generators/gas-engine-generators/900-peak700-running-watts-2-hp-63cc-2-cycle-gas-generator-epacarb-60338.html>
While you're contemplating why you received a well deserved stupid
reply, please consider that it helps to disclose what you're powering,
duty cycle, number of phases required, environmental conditions, and
reliabilty expectations. For example, if you plan to run your
unspecified load for many hours at near the full 1000 watt load, it
will probably burn up the UPS.
 
 
--
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
stratus46@yahoo.com: Dec 17 08:27PM -0800

Thanks for the laugh and Merry Christmas.

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Dec 18 08:25AM -0500

> So what is a recommended UPS based on lack of repair experience?
> Say around 1000W and say around $150 new.
 
> --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
 
Well, if 750W is actually enough and you just want it to ride out
few-minute outages and let your computer shut down gracefully in longer
ones, then those $50 IBM eServer 750Ts from eBay are excellent.
(Hmm...that has a nice ring to it) That plus a new set of batteries
comes in at $100 or so, and you'll have something pretty dependable IME.
 
The IBM-badged ones go cheaper than the (afaik otherwise identical) APS
SmartUPS 750s.
 
Cheers
 
Phil Hobbs
 
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
 
160 North State Road #203
Briarcliff Manor NY 10510
 
hobbs at electrooptical dot net
http://electrooptical.net
Jeff Liebermann <jeffl@cruzio.com>: Dec 18 07:54AM -0800


>Thanks for the laugh and Merry Christmas.
>G²
 
Bah Humbug. (It's the season so I can do that).
 
Recommending a generator is one of my standard replies. If the load
can tolerate being down for the time it takes to start the generator,
then above some number of kilowatts, a generator is cheaper and
better. However, if the load needs to be up 100% and can't tolerate
even a few milliseconds of downtime, then a UPS is required. For
loads that need both fast switchover, and long run times, both a UPS
and a generator are best. For example, the local PSAP (public safety
answering point) has a rather large bank of batteries and a very big
UPS system, which will run most of the emergency center for maybe
10-15 minutes, long enough to get the generator started, synchronized,
and stable.
 
For my self at home, there are only a few things I want to keep
powered up in the event of a power failure. Mostly the internet stuff
and one laptop and monitor. All of those now run either directly from
a battery at 12V, or from a small DC to DC converter. No UPS needed.
(Edison was right. DC rules). Unfortunately, I have a few things
that insist on AC power, so I have a small UPS to run my desktop. That
will eventually go away as I switch to small computahs.
 
Anyway, my point is really that the quality of the answer largely
depends on the quality of the question.
 
 
 
--
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>: Dec 17 09:49AM -0800

On Wed, 16 Dec 2015 11:30:44 -0800, dplatt@coop.radagast.org (Dave
Platt) wrote:
 
>>electric blanket.
 
>Cat's aren't particularly adjustable, warmed or otherwise. They're
>notoriously stubborn.
 
Cat warmer:
<http://802.11junk.com/jeffl/pics/drivel/slides/Cat-warmer.html>
Actually, that's the neighbors cat. She typed "don't you dare try to
move me" on the keyboard as a warning. I found a different computer
to work on.
 
Incidentally, the noisy fan on cold start turned out to the small fan
on the video card. Cleaning and switching to a multi-viscosity oil
change seems to have solved the problem.
 
--
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>: Dec 17 10:13AM -0800

Once upon a time, I was temporarily put in charge of marine radio
manufactories production test department while they searched for
someone to replace my predicessor, who had apparently gone missing,
insane, or both.
 
Among the test techs was one who followed instructions dilligently,
but usually failed to understand what was expected. The techs were
told that in the transmitter RF chain, if they couldn't identify which
device lacked sufficient gain, they could just replace each device in
turn until the culprit was found. This was possible because there
were only 7 devices involved, and the most likely culprits were the
cheap TO-92 devices found at the oscillator end of the chain.
Unfortunately, that was not communicated to this individual, who
proceded to replace devices starting with the rather expensive 25 watt
VHF RF output transistor. Nobody said noticed until I went to the
parts room to replace a 25 watt device that I had blown up in
engineering, and was informed that production test had grabbed all the
available stock. I also noticed that someone had prefixed some of the
printed test procedures to include turning the power on to the test
equipment. I survived for about a month and was very happy when the
company finally hired someone to replace me.
 
--
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>: Dec 17 01:30PM -0500

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:nvt57b1mcjqrqjb7jjltn9j2m9mrccvl51@4ax.com...
> printed test procedures to include turning the power on to the test
> equipment. I survived for about a month and was very happy when the
> company finally hired someone to replace me.
 
Always start with the most expensive part. If it is not bad, it will be
when it is ripped out.
 
I had a Toyota that started running vrey bad with about 130,000 miles on it.
I repalaced the simple things like the plugs, wires, coil and fuel filter.
Nothing helped. From there a Autozone trouble shooting chart indicated a
sensor that was about $ 500. I took it to the local Toyota dealer and let
them look at the problem as I did not want to spend $ 500 and not need that
part. They kept it about 3 weeks and changed a few other parts including
the spark plug wires as I did not use Toyota wire. Finally they changed
that $ 500 sensor and it ran like it should. I would have thought a dealer
could run some tests but seems like they were just parts changers. Really
ticked me off as they had put on about $ 150 worth of parts that were not
needed and still charged me for them not counting on the 3 weeks it took
them.
It may have taken longer but I emailed the Toyota company about how bad the
service was at he end of the second week and got back a very nice email from
them .
Jeff Liebermann <jeffl@cruzio.com>: Dec 17 10:35AM -0800

One of my customers in the computah repair business own a large house
that had been converted to college student housing. My guess is about
15 students crammed into every possible available space. I was hired
by the owner to maintain the Comcast internet, NAS server, printers,
phone system, wiring, and wi-fi, which are all part of the package.
The prime directive was to do everything necessary to prevent the
students from burning down the house, which I interpreted to mean not
let them make any changes or additions to the wiring or equipment.
That has worked fairly well by the honor system for about 8 years.
 
This morning, I get a phone call that the internet and some of the
phones are down. Upon interrogation, I determine that some of the
"makers[1]" in the house had "optimized" the performance of the
Comcast cable modem and VoIP systems yesterday. My initial guess was
that they had managed to scramble the ethernet cables on the 24 port
managed switch running several VLAN's. Unlike ordinary ethernet
switches, a managed switch with traffic logging, required that the
correct cable be connected to the correct port.
 
I had previously suggested that someone should take photographs of the
wiring for this exact purpose. Amazingly, the students found the
flash drive in the envolope that I had place in plain sight, and were
able to display how things were wired before the system was
"optimized". They were able to bring things back online in only a few
additional minutes (I could see the switch come up from home via SNMP)
and only waited a full hour before someone bothered to phone me that
it was fixed and I need not waste a service call to the house.
 
With such a wonderful example of initiative and organized
troubleshooting, I think there may be hope for our next generation of
our country's leaders.
 
 
[1] Make trouble, make a mess, make love, make things break, make a
quick exit, etc...
--
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>: Dec 17 10:52AM -0800

On Thu, 17 Dec 2015 13:30:22 -0500, "Ralph Mowery"
 
>Always start with the most expensive part. If it is not bad, it will be
>when it is ripped out.
 
Never do anything that can't be undone.
 
>ticked me off as they had put on about $ 150 worth of parts that were not
>needed and still charged me for them not counting on the 3 weeks it took
>them.
 
I had almost the same situation, except it was the rear oxygen sensor.
The dealer wanted to replace the very expensive catalytic converter.
The dealers computer diagnostics all pointed to the catalytic
converter. They even called the factory service support number, which
confirmed that the diagnostics conclusively pointed to the catalytic
converter. However, I was able to listen to this conversation and
detected considerable uncertainty and lack of competence on everyones
part. Something seemed wrong, so I decided to do some checking. The
internet was full of the usual mix of wisdom and useless garbage, but
I did manage to find an article suggesting that the rear oxygen sensor
tends to get contaminated by various exhaust products, and that since
it's two orders of magnitude cheaper than a catalytic converter, it
should be replaced first. I replaced it, and all as well.
 
I was curious as to what had just happened, so I went back to the
dealer, told them the story, and asked a few questions. Basically,
there is nobody in the system that knows how to troubleshoot a vehicle
without totally relying on the computerized hardware. The programming
is not intended to nail down the exact cause of a problem, only the
most probable causes, expecting the dealer to replace things in a
rational and logical order based on their experience. In other words,
the computer supplies a shopping list that usually includes a large
number of irrelevant replacement parts and procedures. When calling
factory service support, they don't have experienced techs on the
phones. They just read the computer screen. I was also told that it
was amazing that the diagnostics programs worked because the factory
was constantly making changes and improvements that affected
recommendations.
 
In my distant past, I had the displeasure of integrating BITE (built
in test equipment) in some radios. The test system caused more
failures than it detected. The diagnostics could be easily mislead,
producing insane results. Even worse, it could not diagnose itself.
All I can say is that such diagnostics are NOT easy to do, especially
with a moving target, such as an automobile.
 
 
--
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>: Dec 17 02:58PM -0500

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:v5067bt25cgtgs9kbc2ni5le24t6b12441@4ax.com...
> was amazing that the diagnostics programs worked because the factory
> was constantly making changes and improvements that affected
> recommendations.
 
At work there is a pipe that has about 150 psi of air on it and about 2
inches in diameter. This goes to a regulator that cuts it to about 75 psi
and then to a a control valve that is ran by a computer. This regular has a
habit of getting water in it and in the winter time turning to ice. I got a
call that the system was not working correctly so I cleared the ice from the
regulator. Then an engineer wanted me to rebuild or change out the control
valve because it was not working. I told her that I was not going to do it
unless there were more problems. She got very mad at me and told me that
her data from the computer said the control valve was not working. I told
her I did not care what her old data said, it was not the control valve.
 
The control valve can not control anyting if no air is getting to it for it
to control.
 
Had a lot more trouble out of some of the production engineers because of
the computer. The process probably monitored over 1000 points and stored
that data for a month. That data could be called up in a graphical form.
Only problem is some of the data points may be 1 to 5 moments apart.
Something could hapen and would not be caught during that time frame. Then
it would look like something other than the origional problem was the cause.
 
Computers are good,but you have to undestand what they are trying to tell
you and sometimes they are just wrong.
"pfjw@aol.com" <pfjw@aol.com>: Dec 18 07:49AM -0800

Um.... Um....
 
Have you checked the receptacle at home? And for proper polarity?
 
Some monitors will not function if not properly polarized. Just a thought.
 
Peter Wieck
Melrose Park, PA
Jeff Liebermann <jeffl@cruzio.com>: Dec 17 09:56AM -0800

On Wed, 16 Dec 2015 11:34:43 -0800, dplatt@coop.radagast.org (Dave
Platt) wrote:
 
>>you see it. I posted the picture previously and Phil Allison caught
>>the problem almost instantly. I didn't.
 
>Are *all* *four* of those large caps installed backwards?!?
 
Yep. When I do something wrong, I'm consistent. As I previously
ranted, when I find one bad cap of a type and value, I replace *ALL*
the caps of the same type and value. My time is more expensive than
the extra caps.
 
>Yah. Amazing you didn't have a chassis full of oily linguine there.
 
Actually, the machine ran quite nicely for a day or two the first time
I put the caps in backwards. Eventually, it started acting strangely
so I retreived it from the customers. All 4 caps were bulging. So, I
replaced all 4 caps again, putting them in backwards again. That's
when I noticed that they were getting hot, which prompted my initial
Usenet posting. I too would have expected at least a small explosion,
but nothing happened.
 
--
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
John Robertson <spam@flippers.com>: Dec 17 10:04AM -0800

On 12/17/2015 9:56 AM, Jeff Liebermann wrote:
> when I noticed that they were getting hot, which prompted my initial
> Usenet posting. I too would have expected at least a small explosion,
> but nothing happened.
 
Nice that there were no explosions - I'm sure your customer would have
been nonplussed.
 
(ducking from the coffee explosion)
 
John ;-#)#
 
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
"Ralph Mowery" <rmowery28146@earthlink.net>: Dec 17 01:19PM -0500

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:ndt57bhk8bil21l66rvfp34dj8r813lhoi@4ax.com...
> when I noticed that they were getting hot, which prompted my initial
> Usenet posting. I too would have expected at least a small explosion,
> but nothing happened.
 
Interisting it ran at all.
 
It is easy to get into a bad pattern of doing things. A coworker and I were
repairing some flouresence lights in the plant. Got to one and put in new
tubes and it did not come on. This did not phase us as we often will get a
bad tube or so as there are thousands in the plant we often will replace
over 100 tubes in a day. Sometimes we get bad tubes so put in another set
and still no light. Decided it was the ballast, so replaced that. Still no
light. Knew we had power as there were about 20 other lights in the room.
Replaced the ballast 2 more times and sitll no light. This ballast had been
replaced before as there were several places where the wires were spliced
together with wire nuts. One would thing with only 8 wires it would be easy
to get it going. Got time to go home. I went up the next day by myself
and decided to try one more time. This time I removed all the wires and
instead of just going by the color of the wires, actually trace the wiring
out. This time it lite just fine.
 
What we were doing wrong was just matching the wire colors and as it had
been replaced before the colors did not go to the same place.
Chuck <ch@dejanews.net>: Dec 17 04:03PM -0600

On Thu, 17 Dec 2015 05:22:59 -0800 (PST), "pfjw@aol.com"
 
>Given that these beasts blow up by the numbers, I generally install sockets for the outputs, and do the TIP mod once ALL else is under control.
 
>Peter Wieck
>Melrose Park, PA
Peter,
 
Who in their right mind would still be using one of these? They were
considered to be an awful amps back in the 70s. One I saw burned down
a house. The carbon resistors caught fire and there happened to be a
curtain draped across the top of the amplifier. After seeing this
amp, I refused to work on them.
 
---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
Jeff Liebermann <jeffl@cruzio.com>: Dec 17 02:38PM -0800

On Wed, 16 Dec 2015 20:13:52 -0600, "Shaun" <stereobuff07@gmail.com>
wrote:
 
>"Cursitor Doom" wrote in message news:n4miat$8a6$1@dont-email.me...
 
>1. Assume nothing.
 
1a. Trust nobody (except your certificate authority).
1b. Believe no one.
1c. Presume nothing.
1d. Ignore fashionable explanations.
1e. Distrust authority.
1f. Ignore all advice.
1g. Test all new replacement components.
 
>2. If at first you don't succeed, destroy any evidence that you even tried!
 
I never make the same mistake twice. Five or six times is my average.
 
>3. Try Percussive maintenance first. If it works after you bang it, it has
>intermitant connections, or components.
 
Nope. Clean the device first. Depending on the type of filth, that
can be blowing off the dust with compressed air, or washing with a
household cleaner to remove fingerprints, dirt, crud, slime, food,
whatever. Cleaning allows you time to inspect the device, where you
might visually find the problem. Often, the problems go away with the
filth. Customers don't believe that anything has been repaired unless
it's clean.
 
Instead of beating on the box, try turning it upside down and shaking.
If you hear something rattle around, you've either found the problem,
or what's left of some component. Loose screws and spare parts on new
electronics are amazingly common.
 
--
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
"pfjw@aol.com" <pfjw@aol.com>: Dec 17 02:47PM -0800

Ah, they ain't no how as bad as all that these days. Between the various mods, Factory and susequent, they have been rendered pretty bullet-proof, very stable, and as simple SS amps go, fairly melifluous. They were made in the uncounted tens of thousands, and uncounted thousands survive. With a few hours of simple work and not much cost, a decent 50+ watt amp may be had. As it happens, I keep two (full mods) that see very rough service, and have done so in one case for 2 years of 24/7 use in a desert climate, not conditioned. 100F+ from may to November. It now sits in my shop system seeing about 3 hours per week, these days.
 
Who would put a curtain over an amp capable of frying an egg in the first place?? That smacks of terminal idiocy.
 
Peter Wieck
Melrose Park, PA
Cydrome Leader <presence@MUNGEpanix.com>: Dec 18 12:45AM

> I could get out of him was he just pressse the buttons and the lights should
> come. He did not seem to know where the equipment was, just the indicator
> lights..
 
Give him credit for at least swapping out indicator bulbs.
Cydrome Leader <presence@MUNGEpanix.com>: Dec 18 12:54AM

> take with us.
> Sometimes I would make notes on the copies and leave them in the electrical
> cabinet, or just write inside the cabinet with a marking pen.
 
There always seems to come a point when people stop updating the stickers
inside the cabinet or the service books with all updates, past problems
and more importantly field modifications and why they were done. This
seems to happen around the time the safety switches start wear out and get
bypassed or panels and covers start to go missing.
Jeff Liebermann <jeffl@cruzio.com>: Dec 17 05:05PM -0800

On Tue, 15 Dec 2015 18:31:14 -0500, "Ralph Mowery"
 
>Sometimes I would make notes on the copies and leave them in the electrical
>cabinet, or just write inside the cabinet with a marking pen.
 
What? You don't like my method of documenting changes?
<http://members.cruzio.com/~jeffl/k6bj/K6BJ%20Repeater/slides/Documentation.html>
I think it's been like that since at least 2001.
 
Incidentally, I use a special ink for the purpose, that fades to
invisibility in about a year. It helps keep the manuals nice and
clean.
 
--
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
"Mark Zacharias" <mark_zacharias@sbcglobal.net>: Dec 18 06:37AM -0600

<pfjw@aol.com> wrote in message
news:a117378b-ecb2-4aaf-be0f-c6bac46c07a6@googlegroups.com...
>place?? That >smacks of terminal idiocy.
 
>Peter Wieck
>Melrose Park, PA
 
 
Personally I wouldn't use an ST-120 simply because I find capacitor-coupled
amps to sound muddy, and yeah - I hated working on the things. Piece of crap
really.
 
Prefer direct-coupled amps (with a competent protection circuit!) although I
do like an autoformer coupled McIntosh...
 
Mark Z.
John-Del <ohger1s@aol.com>: Dec 17 09:20AM -0800

On Wednesday, December 16, 2015 at 4:03:33 PM UTC-5, Dimitrij Klingbeil wrote:
> replacement.
 
> Regards
> Dimitrij
 
Thanks Dimitrij, but you're talking way over my head on eeproms! Actually, I understand *some* of that info, but not enough to pick a suitable substitute..
 
In any case, I ordered 10 of the correct part from Alibaba and I'll have them in two weeks. Fortunately, I have the .bin file that I grabbed out of another of the same model that I repaired earlier this year for a different problem as Funai won't sell the eeprom for this model, only the complete main board.
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