32" Goodmans TV

[tom66]

I got this TV for cheap.

Model Goodmans LD3262D.

Symptoms are it is stuck in standby. Sometimes it will switch on and work for a few hours.

I took it apart and none of the caps look visibly bad.

Problem is there are like 20 different values of cap in it, so I have to order a lot of caps and replace them to get it working.

The caps are cheap: Chong, Aishi, Teapo, G-Luxon and Samxon (good?) From the number of them and the inconsistency it looks like they picked whatever caps they could get the cheapest or quickest.

I don't have an ESR tester, only a multimeter with basic cap range. I *do* have an oscilloscope to probe power supply lines so I can check for ripple.

[sam_sam_sam]

Re: 32" Goodmans TV

Here is what I would if the monitor is more than two years old I would replace
ALL the caps on the inverter/power board

I just repair a monitor that was made in 2004 and I replaced ALL the caps on the Power board and works great now

ALL the caps read 10% or more under what the caps had print on them so you be the judge and jury on whether or not to change all the caps on the Power board

[jsog]

Re: 32" Goodmans TV

With a signal generator, you can test ESR with the oscilloscope. Not as convenient as a dedicated ESR meter, but better than none at all.

http://www.repairfaq.org/sam/captest.htm#ctsim
http://www.electronics-diy.com/elect...tic.php?id=948
http://emcesd.com/tt020100.htm

Some of those circuits aren't much less complicated than a full analog ESR meter. http://members.shaw.ca/swstuff/esrmeter.html works. If you have a reasonably good stock of junk, you might have all the parts already.

Edit: page with a bunch of ESR meters in all styles:
http://kripton2035.free.fr/esr-repository.html

[tom66]

Re: 32" Goodmans TV

With a signal generator, you can test ESR with the oscilloscope. Not as convenient as a dedicated ESR meter, but better than none at all.

http://www.repairfaq.org/sam/captest.htm#ctsim
http://www.electronics-diy.com/elect...tic.php?id=948
http://emcesd.com/tt020100.htm

Some of those circuits aren't much less complicated than a full analog ESR meter. http://members.shaw.ca/swstuff/esrmeter.html works. If you have a reasonably good stock of junk, you might have all the parts already.

Edit: page with a bunch of ESR meters in all styles:
http://kripton2035.free.fr/esr-repository.html

A signal generator is on my wishlist, but I don't have one yet.

Here is what I would if the monitor is more than two years old I would replace
ALL the caps on the inverter/power board

I just repair a monitor that was made in 2004 and I replaced ALL the caps on the Power board and works great now

ALL the caps read 10% or more under what the caps had print on them so you be the judge and jury on whether or not to change all the caps on the Power board

I probably will do this. What is the best source for various values of caps? Farnell wants me to order minimum 5; Mouser wants £12 shipping.

I was measuring the standby power supply of the TV when it tries to turn on. It measures about 8.18V - 8.24V - that's quite a large ripple. I'm suspicious of the standby caps the most, for this reason.

[jsog]

Re: 32" Goodmans TV

"Signal generator" can be as simple as a single resistor. The standalone meters usually use a single chip like a 74HC14 or even a 555 timer to generate a signal.

[tom66]

Re: 32" Goodmans TV

This is bizarre.

I was scoping the 8V line and I notice it runs at 8.18V idle but every so often spikes to 8.25V. Perhaps that is caused by it cycling power: it's trying to start up, but failing.

The 1.8V supply measures at 1.887V and the 3.3V supply at 3.324V... both seem perfectly in spec.

I've ordered some replacement standby caps. I'll only replace the caps powering the inverter board if I have to.

[dumpystig]

Re: 32" Goodmans TV

i had a similar prob which I have just fixed. If you post more detail of what happens from plugging in the TV I may be able to help. To start with if all your standby voltages are correct check PL803, Pin 1, 3V2 - this is the output from the Mainboard that fires up the inverters.

[tom66]

Re: 32" Goodmans TV

i had a similar prob which I have just fixed. If you post more detail of what happens from plugging in the TV I may be able to help. To start with if all your standby voltages are correct check PL803, Pin 1, 3V2 - this is the output from the Mainboard that fires up the inverters.

When plugging in and turning on the TV, the blue power LED lights up, but nothing more. If I listen carefully, I can hear a faint whistling sound - a characteristic switching power supply sound. According to the person I bought it off, it will occasionally switch on, but I don't know whether or not to trust them.

I've looked all across the board for a PL803 but can't find it. Can you give me a location to look in? The only connector which goes to the inverter is PL802, it is black and has many rails on it. Could a failing inverter/backlight be causing my problem? The TV has no sound and has no "2 secs to black" issue.

[tom66]

Re: 32" Goodmans TV

Oh, nevermind, just found PL803. I tried both sides (not sure which is pin #1) and both measure 0V. Scope shows a tiny bit of ripple (<20mVp-p) possibly just caused by the SMPS on the board for the standby supply.

[tom66]

Re: 32" Goodmans TV

OH! I feel like a complete DUMBASS!

I haven't been turning it on properly, that's why! You need to turn on the switch AND press the power button to turn it on.

Just got it to switch on and show "No Signal" on the display. It makes a rather loud buzzing sound from what I suspect to be the PFC transformer. Maybe this is shielded by the case or maybe it's just a crap TV.

Now I can try and debug the intermittent power issue reported by the original owner.

[dumpystig]

Re: 32" Goodmans TV

My chassis Mainboard is Vestel 17MB22-2, PSU is Vestel 17PW20.1. I already see your PSU is the same, what about your Mainboard? PL803 Pin 1 is on the left, thin white wire.
D/l from this link, it helped me out a lot
http://www.megaupload.com/?d=ER9AMF73

[tom66]

Re: 32" Goodmans TV

My chassis Mainboard is Vestel 17MB22-2, PSU is Vestel 17PW20.1. I already see your PSU is the same, what about your Mainboard? PL803 Pin 1 is on the left, thin white wire.
D/l from this link, it helped me out a lot
http://www.megaupload.com/?d=ER9AMF73

Mainboard is the same. Looks like we have identical TVs. This will be helpful.

Are we looking leftmost pin on the PSU or on the mainboard - connector swaps around between boards.

[dumpystig]

Re: 32" Goodmans TV

PSU - the corresponding plugs at the M/b are numbered differently. Have you d/l from the link above? You will find 2 pages with the layouts of both boards and associated voltages.

[tom66]

Re: 32" Goodmans TV

PSU - the corresponding plugs at the M/b are numbered differently. Have you d/l from the link above? You will find 2 pages with the layouts of both boards and associated voltages.

Yeah, thanks for that. Looks excellent. Anyway:

When plugged in while in standby: 0V
When plugged in while on, but not working: 0.01V
When plugged in and while working: 3.21V (note: it jumps to 0.04V just before starting and then to 3.21V and then the TV works and shows "no signal".)

I'll scope pin #1 later after the TV stops working again.

[dumpystig]

Re: 32" Goodmans TV

Haha I've just seen post#10. good luck, if you have any probs let me know, I have gained more experience of these boards over the past 2 weeks (and it's done my head in!).

[tom66]

Re: 32" Goodmans TV

Haha I've just seen post#10. good luck, if you have any probs let me know, I have gained more experience of these boards over the past 2 weeks (and it's done my head in!).

Thanks for your help

It's not turning on right now and the RUN pin (pin #1) is at 0.01V.

According to the Sanyo service manual PL811 should be pulsing. But it isn't. It's at a fixed 8.27V (when in standby.) So where is this pulsing produced and is it required to start the power supply? Would it be temperature dependent e.g. a bad cap?

[tom66]

Re: 32" Goodmans TV

Okay, I got it to power on after a lot of coercing.

I found a service manual for a similar TV. The power supply is different (I believe it adds support for plasma panels too), but a lot of the component designators are the same and the layout is similar, so it might be helpful. I've attached the manual.

Anyway, there's a pin called STBY on PL803. When it is not working, it is at 0.09V. When it is working, it is at 2.5V. Could the control board be telling the PSU to turn on using this? Why isn't it going high normally?

PL803 when ON:
#1: 3.204V
#2: 0.512V
#3: 0.050V - 0.150V (climbs slowly)
#4: 3.364V
#5: 2.578V
#6: 0.050V
#7: 34.03V (for tuner?)
#8: 11.08V
#9: 0.009V
#10: 0.009V

PL803 when set is in standby:
#1: 0.001V
#2: 0.000V
#3: 0.001V
#4: -0.003V
#5: 0.060V
#6: 1.754V
#7: 33.02V (decays slowly)
#8: 0.030V
#9: 0.009V
#10: 0.009V

PL803 when trying to start:
#1: 0.010V
#2: 0.000V
#3: 0.150V - 0.180V
#4: 0.323V
#5: 0.059V
#6: 0.055V
#7: 32.40V (decaying slowly)
#8: 0.128V
#9: 0.009V
#10: 0.009V

This is odd, because I would expect pin #5 to be the signal from the mainboard to turn on the TV, but there is no significant signal on it.

But, when scoping it... I think it has a clue. While it is trying to turn on it goes crazy! It changes between several waveforms - at one point 2.5Vp-p - but eventually goes almost completely dead. Sometimes these waveforms show up when the set is switching on and sometimes not. And sometimes pressing the power button on the remote makes this pin go high for maybe half a second, then go low. Something is stopping it fully starting.

I've ordered some caps, but it seems less and less likely to be a cap issue now.

Maybe I should try jumpering this to 2.5V to get the set to switch on?

[dumpystig]

Re: 32" Goodmans TV

Yep, the answer is maybe related to Pin 5...

Is the manual you have Hitachi No. 0234? That's the one I've been working from.

[tom66]

Re: 32" Goodmans TV

Yep, the answer is maybe related to Pin 5...

Is the manual you have Hitachi No. 0234? That's the one I've been working from.

I'm trying to attach the manual right now... but it's taking a long time. I found it here: http://www.eserviceinfo.com/download.php?fileid=56543

It is indeed Hitachi 0234.

[dumpystig]

Re: 32" Goodmans TV

No need for the attachment, we're on the same manual.