Digest for sci.electronics.repair@googlegroups.com - 2 updates in 1 topic

9:40 AM Penedão 0 comments
bruce bowser <bruce2bowser@gmail.com>: Aug 30 09:55AM -0700

On Tuesday, August 16, 2022 at 2:11:21 PM UTC-4, Unum wrote win alt.global-warming:
> of all expected projects would nearly quadruple it.
 
> Notably, FERC's forecast predates President Joe Biden signing into law the
> Inflation Reduction Act, and that will likely ramp up solar growth even more.
 
Aww, Joe Manchin Republicans sink deeper and deeper.
"Peter W." <peterwieck33@gmail.com>: Aug 30 11:06AM -0700

The problem remains that unsubsidized solar is a poor investment as compared to wind. And about on-par with nuclear. Nuclear, well-executed of course, is also very clean and has a much smaller footprint per megawatt than solar.
 
2.5 acres-per-MW for solar.
0.84 acres per MW for nuclear.
Wind turbines take up negligible land, but must be placed so far apart that the allowance is very roughly 16 acres-per-turbine. All of which may be farmed, or forested, or used for recreation. Or, even lived in.
 
As to disposing of nuclear waste, that is purely, only and entirely a matter of political will. There are over 1500 underground nuclear test sites in Nevada that will be dangerous for well over 500 years, and 'hot' for much longer than that. Each one of which has a diameter somewhere at/greater than 75 meters. Consider how much volume even one such cavity will hold.
 
Peter Wieck
Melrose Park, PA
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Digest for sci.electronics.repair@googlegroups.com - 3 updates in 2 topics

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kayge <kgpupswitch@gmail.com>: Aug 30 01:40PM

Hi and thanks so much for the help. Pretty sure the LED's are 3V as my
meter on diode check only puts out a little over 2V. My meter is able to
make the LED's light up dimly, but enough to see if they're working.
Unplugged ribbon from main to TCON, no change. I didn't see a rest switch
near the RF connector but rather on the adjacent side near composite video
and stereo audio inputs (phono or RCA jacks) I pressed this for 15 sec.
like you said, no change. Any other ideas? If not I give up and I'm
sending the boards back.
"ohg...@gmail.com" <ohger1s@gmail.com>: Aug 30 08:55AM -0700

On Tuesday, August 30, 2022 at 9:40:08 AM UTC-4, kayge wrote:
> and stereo audio inputs (phono or RCA jacks) I pressed this for 15 sec.
> like you said, no change. Any other ideas? If not I give up and I'm
> sending the boards back.
 
Long shot but easy to try: unplug the wifi card and see if the main responds.
 
There are two versions of the Hisense 58R6E apparently, different main boards but they use the same power supply. Did you measure the voltage on XP702 pins 2N and 2P? If you are getting a large voltage (150 plus) but no visible flash from the back lights as seen from the back side of the display, you still have a problem inside the display. I'm assuming your LED strips are new, but if you bought used ones, there's a high probability they're bad. I've also found bad connectors that plug into the LED strips. I never reassemble any display until the back light runs for at least an hour. If you are not getting that voltage kick on that connector, then the problem is one of the boards.
 
If you are getting no voltage/flash on the back lights, then check the "STB" line on the power supply connector. On these, the stb is not the standby voltage for the main as you might expect, but the turn on command from the main (counter intuitive but this is the crap we run across). The STB line takes the power supply *out* of standby on these TVs and puts the supply in full run. The actual standby voltage from this power supply is your 12v, which is there because you're getting your red power LED blinking. So check the STB line for voltage to the ground screw near the connector. The STB line should go high (3.3-5V prob) when you push the power button. If you are getting a high on the STB, then check the voltage on the two 450V PFC caps. The voltage on those caps should be close to 400V. If you get a command on the STB but the voltage on the PFC caps stays low (about 160V but doesn't go to 400V), then your PFC controller IC on the bottom of the power supply board is probably bad. It's surface mount but they are available. They do have a drop of glue underneath so it's a good idea to heat it well with hot air before you remove it. If the 400V comes up, it's either the LED supply section of the power supply or the back light command from the main (BRI) isn't there.
 
If you get no command on the STB line from the remote or power button being pushed, the main is not commanding the power supply to turn on and the main is your problem.
 
Any boards you are buying are salvage boards, and I know from experience that these are NOT checked despite what the seller tells you. When I'm forced to buy a board, I find about 30% of them bad when I get them.
"ohg...@gmail.com" <ohger1s@gmail.com>: Aug 29 01:37PM -0700

On Sunday, August 28, 2022 at 1:52:22 PM UTC-4, kayge wrote:
> replaced the mother board, no change. Could the T-con board be causing
> this? Does the T-con talk back to the mother? Any help would be greatly
> appreciated.
 
The vast majority of this model I see need LEDs followed by bad mains. I never repaired/replaced a power supply or tcon. The tcon doesn't talk to the main AFAIK (most don't, very few exceptions).
 
You can try removing the LVDS cable on the tcon. If it starts and turns on the back lights, plug it back in and remove the ribbons to the display to see if the display or the tcon is loading it down.
 
You said you found some bad LEDS, did you note the voltage of them? They're either 3V or 6V. There are like 50 in this model, so you should be getting about 150V between pins 2N and 2P on the power supply when you start the TV, or about twice that if this model uses 6V LEDs. If there's a problem with the LED array, it will appear briefly and disappear, so have your meter on those points before you start it.
 
There's an excellent chance the main you bought is bad. There's a tact switch near the RF input on this board. Push and HOLD it in for at least 15 full seconds, release and push the power button to see if it will start and try that on your original board as well.
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Digest for sci.electronics.repair@googlegroups.com - 2 updates in 2 topics

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kayge <kgpupswitch@gmail.com>: Aug 28 05:52PM

Trying to fix this 58" tv for a friend. The red LED blinks three times
then goes out for a few seconds, then repeats. Checked the backlight LED's
and 3 were blown, so I replaced all 5 10-LED strips. Same thing, blinking
red LED. Then I replaced the power supply board, no change. Finally I
replaced the mother board, no change. Could the T-con board be causing
this? Does the T-con talk back to the mother? Any help would be greatly
appreciated.
kayge <kgpupswitch@gmail.com>: Aug 28 05:42PM

Test.
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Digest for sci.electronics.repair@googlegroups.com - 3 updates in 1 topic

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David Farber <farberbear.unspam@aol.com>: Aug 26 04:14PM -0700

On 8/24/2022 7:00 PM, Phil Allison wrote:
> Lotta resistors about too.
> Dead easy to check them for opens.
 
> .... Phil
 
I removed the 8-pin DIP op amp and tested one of the amps as described here:
https://www.circuitbread.com/ee-faq/what-are-the-golden-rules-of-op-amps
I used the schematic at the very bottom of the page as the test setup.
 
The result of the test was that the non-inverting input voltage (4.5V)
did not match the inverting voltage input (0.7V) and according to one of
the golden rules of op amps:
 
"In a circuit with negative feedback, the potential difference between
the inverting and non-inverting inputs is zero...."
 
That means the op amp is defective.
 
By the way, many of the voltage +/- inputs for the quad and dual op amps
when measured in-circuit were amiss. In other words, the non-inverting
input voltages were not equal to the inverting voltages but perhaps
there was no feedback loop? (too many pc traces for me to keep track of.)
 
In summary, I'm going to replace both chips. I think I checked every
semiconductor, resistor and capacitor on the board and I'm fairly
confident that my diagnosis is correct.
 
Thanks for your reply.
--
David Farber
Los Osos, CA
Phil Allison <pallison49@gmail.com>: Aug 26 04:52PM -0700

David Farber wrote:
 
=================

> > Dead easy to check them for opens.
 
> > .... Phil
 
> I removed the 8-pin DIP op amp
 
** What op-amp?
 
FYI the LM2903 is a *comparator* so is the LM2901.
 
https://www.st.com/resource/en/datasheet/lm2903.pdf
 
> and tested one of the amps as described here:
 
** Irrelevant.
 
> By the way, many of the voltage +/- inputs for the quad and dual op amps
> when measured in-circuit were amiss.
 
** Normal for comparators.
 
Your circuit is * non linear * and uses switching to control the SCR and hence output of the charger.
 
 
...... Phil
David Farber <farberbear.unspam@aol.com>: Aug 26 08:39PM -0700

On 8/26/2022 4:52 PM, Phil Allison wrote:
 
> ** Normal for comparators.
 
> Your circuit is * non linear * and uses switching to control the SCR and hence output of the charger.
 
> ...... Phil
I missed that point. I will reconfigure my test circuit and report back...
 
Thanks for your reply.
 
--
David Farber
Los Osos, CA
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Digest for sci.electronics.repair@googlegroups.com - 5 updates in 3 topics

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bitrex <user@example.net>: Aug 25 11:26AM -0400

Is there a suitable modern replacement for the ua208a TO-99 can-type
op amp as used in e.g. the HP oven oscillators, that's available and
doesn't cost an arm and a leg?
 
<https://datasheetspdf.com/pdf/1305470/Fairchild/UA208A/1>
 
Probably less expensive to just buy another module, maybe
ehsjr <ehsjr@verizon.net>: Aug 24 06:44PM -0400

On 8/23/2022 10:24 PM, bob prohaska wrote:
 
You want a precision that is doomed by the technique you
intend to use - stacking cells. Instead, build a voltage
reference using a single IC: ADR01 available from Digikey
https://www.digikey.com/en/products/detail/analog-devices-inc/ADR01AUJZ-REEL7/996117
It provides 10V output at +/- point one percent (.1%)
 
Calibrate your meters to that.
 
Ed
amdx <amdx@knology.net>: Aug 25 05:29AM -0500

On 8/23/2022 9:24 PM, bob prohaska wrote:
> CR2032 cells are readily available, but voltage details are scarce.
 
> Thanks for reading,
 
> bob prohaska
 
Aliexpress, Ebay and Amazon have some for under $10, and more for under $20.
 
David Farber <farberbear.unspam@aol.com>: Aug 24 05:34PM -0700

On 8/21/2022 9:28 PM, Phil Allison wrote:
 
> ** Read my first post again.
 
> SCRs, once triggered, conduct large currents with small voltage drops.
 
> ..... Phil
 
Finally got around to testing the SCR and it works perfectly. The only
other active components other than the power supply diodes are the two
IC's, LM2901 and LM2903.
 
Thanks for your reply.
 
--
David Farber
Los Osos, CA
Phil Allison <pallison49@gmail.com>: Aug 24 07:00PM -0700

David Farber wrote:
 
> > ** Read my first post again.
 
> > SCRs, once triggered, conduct large currents with small voltage drops.
 
> Finally got around to testing the SCR and it works perfectly.
 
** Yep - expected that.
 
The only
> other active components other than the power supply diodes are the two
> IC's, LM2901 and LM2903.
 
** I see a TO92 pak transistor near the SCR.
Lotta resistors about too.
Dead easy to check them for opens.
 
.... Phil
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Digest for sci.electronics.repair@googlegroups.com - 7 updates in 1 topic

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David Farber <farberbear.unspam@aol.com>: Aug 19 07:39PM -0700

This Schumacher 1042A-PE battery charger stopped functioning today. It
seemed to work for a little while but when I noticed the car battery's
voltage wasn't slowly increasing after performing a 2 amp charge for 2
hours, I checked the voltage at the charger's cables and it was 0 volts.
The continuity of the switches and cables were all good. I did find a
power semiconductor which I could not identify, BTW70-200SN. I looked in
an old ECG cross-reference book and the closest match was for a
BTW69-800 which is an SCR in a TO-218 package. The package seems to
match the device I'm looking for. I made some measurements with my
Simpson 464 DVM on the 2k ohm scale. Pins 1 and 3 measure 38 ohms
regardless of test lead polarity. All other combinations of continuity
measure open circuit. In circuit, pins 1 and 2 are soldered together.
Any idea what this component is or how to test it?
 
Thanks for your reply.
 
David Farber
Los Osos, CA
Phil Allison <pallison49@gmail.com>: Aug 19 09:08PM -0700

David Farber wrote:
=============
 
> regardless of test lead polarity. All other combinations of continuity
> measure open circuit. In circuit, pins 1 and 2 are soldered together.
> Any idea what this component is or how to test it?
 
** Could be an SCR maybe.............
 
With a 1A, current limited, DC supply of about 12 V, + on the anode - on the cathode, apply a brief pulse of +50mA at +1.5V to the gate with - on the cathode as well. The 12 volt supply should the be clamped at about +1.2V.
You 38 ohm readings are normal.
 
 
..... Phil
Jeff Liebermann <jeffl@cruzio.com>: Aug 19 10:25PM -0700

On Fri, 19 Aug 2022 19:39:03 -0700, David Farber
 
>This Schumacher 1042A-PE battery charger...
 
Are you sure about that model number? Methinks that SE-1052A-PE is
more likely.
 
 
--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558
David Farber <farberbear.unspam@aol.com>: Aug 19 11:30PM -0700

On 8/19/2022 10:25 PM, Jeff Liebermann wrote:
 
>> This Schumacher 1042A-PE battery charger...
 
> Are you sure about that model number? Methinks that SE-1052A-PE is
> more likely.
 
Youthinks correctly! It is a 1052A.
 
Thanks for your reply.
--
David Farber
Los Osos, CA
Jeff Liebermann <jeffl@cruzio.com>: Aug 20 12:09AM -0700

On Fri, 19 Aug 2022 23:30:27 -0700, David Farber
 
>> Are you sure about that model number? Methinks that SE-1052A-PE is
>> more likely.
 
>Youthinks correctly! It is a 1052A.
 
Unfortunately, that didn't help when looking for information using
Google search. I couldn't find anything on the SE-1052A-PE except the
owners manual. No schematics or articles on repairing it. No photos
of the inside.
<http://powertool.manualsonline.com/manuals/mfg/schumacher/se_1012d_se_1052.html>
Notice that the user manual covers a range of models which probably
share similar circuitry. Try searching for the other models.
SE-1010-2, SE-1012D, SE-1052, SE-1250
 
--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558
Jeff Liebermann <jeffl@cruzio.com>: Aug 20 12:28AM -0700

On Sat, 20 Aug 2022 00:09:28 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:
 
>Notice that the user manual covers a range of models which probably
>share similar circuitry. Try searching for the other models.
>SE-1010-2, SE-1012D, SE-1052, SE-1250
 
Bingo, except that there's no SCR in the schematic.
<https://www.fixya.com/support/t25414948-wiring_diagram_switch_se_1052>
<https://www.fixya.com/support/t7882270-looking_wirring_diagram>
Kinda looks like just the PCB wiring and not the complete unit. This
is from a different charger (SE-1275A) that MIGHT have the same
wiring. How close are the drawing and schematic to what you have?
 
 
--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558
David Farber <farberbear.unspam@aol.com>: Aug 20 08:38AM -0700

On 8/19/2022 9:08 PM, Phil Allison wrote:
 
> ..... Phil
 
Hi Phil,
 
Looks like I have to make another correction. Jeff pointed out the model
number I posted was wrong, the correct model is 1052A-PE
 
The other correction is that pins 1 and 2 of the "SCR" are NOT soldered
together on the pc board. Pin 2 (center pin) is snipped off and the
connection is made through the component's heat sink. This is the same
heat sink which is electrically common to one end of four discreet
(bridge?) diodes.
 
Getting back to the testing of the SCR (if it is an SCR), how do I
identify anode, cathode, and gate?
 
Thanks for your reply.
--
David Farber
Los Osos, CA
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Digest for sci.electronics.repair@googlegroups.com - 1 update in 1 topic

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vjp2.at@at.BioStrategist.dot.dot.com: Aug 02 06:24PM

Many thanks to both replies.
 
I was leading to the conclusion that BLU shuts off USB OTG, for which I
needed to root. I switched on developer mode and the bootlogger switch. But
KingoRoot refused to root on grounds of 0x17ae78 error, and RootEssentials
showed no vold.fsab in etc, only a volte-cfg.xml.
 
I don't get to choose maufacturer or carrier, so am stuck with this BLU C5L
with Android 11 running on a reseller of T-mobile. My Prior phone was an
LG423 running on what appeared to be a GSM reseller of CDM Verizon.
 
--
Vasos Panagiotopoulos panix.com/~vjp2/vasos.htm
---{Nothing herein constitutes advice. Everything fully disclaimed.}---
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