Dude is bringing over a Hitachi P50S601 (plasma 1080)

[cadiman]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

Don`t worry about being a newbee. I am still a newbee to everything and always learning. (to:leo the noob) I make alot of mistakes and I invest in items to learn on.

I can accept a loss on anything I am repairing as long as I learn something. It has always been my career to learn and gain knowledge on everything. The problem is the more I learn the dumber I feel and that just makes me try harder. I guess that is a good thing.

The heat sink is most likely also part of the circuit and should be a few hundred ohms.

Pending your meter setting, 000 is not good unless you are checking for continuity.


I have repaired 4 of these tvs and I don`t feel I have learned much. The last two just needed buffers and the two caps and it was fine.

If all the boards are plugged in and one is bad the power supply will power up for about 2 seconds (on these models) and go into protect mode. (failed y board, x board or buffers)

The bad caps don`t kill the buffers. The buffers kill themselves. (heat sinks needed)

I have had these tvs with just bad caps (100v 3300uf). (power supply will go into protect mode)

If the power supply does nothing then you have mainboard or power supply issue.

You said missing stand-by power possibly.

Again these are a bit tougher to troubleshoot than most tvs. Similar to Pioneer.

The original or beginning post doesn`t make any sense. I have never had these tvs with sound but no video, only l/g and samsung.

This tv is worth fixing and a new 499.00 plasma is not the same tv.

I am sure of at least that much.

[leo_the_noob]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

I was just looking over that Y sus board and checking the MOSFETS for shorts. I did come across a diode D44F which is a FCU20UC30 fast recovery diode. The diode checks Ok with meter , infinite resistance in one direction and practically nothing in the other but I noticed the 2 anode legs on the diode both short to the heatsink the diode is mounted to. Is this normal? I know it's badnews when a MOSFET shorts to it's heatsink but not sure about diodes. YES I AM A NEWBIE. Trying my best guys and learning a lot here but any help is welcome. Thanks

[leo_the_noob]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

[QUOTE=cadiman;230658]Those 100v 3300 uf caps are bad on every one of these power supplies and very common failure.

the secondary voltages are running at 85 volts at these caps.

I have not had any other cap issues on this power supply other than these two large caps.

These are narrow caps and you have to watch when ordering replacements.

The buffers fail on these and can take out the y drive.

QUOTE]

Cadiman I was just given one of these sets by a friend at work. I checked both upper and lower buffer boards and found 2 bad buffer ICs in each board plus the swollen 100v 330uf caps on the power supply. The cost of the buffer ICs is 10$ each so I figured it wouldn't cost much more to replace the entire boards vs. time and money to replace individual IC chips. I've replaced the bad caps on the power supply and powered up the TV with buffers removed. I'm getting good Vs and Va voltages but they only stay up for about 1 minute before going down. I wasn't sure if this was due to protection mode or not. I tried connecting a good upper buffer board and powering up. The TV showed a picture on half of the panel but every other line was black and the part of the screen that was lit was just a green snowy mess. I quickly turned it off before I blew a buffer board. I removed that buffer and installed the good lower buffer. Same thing, half of panel lights up with every other line blacked out and remainder of image just green snow. I checked these new buffer boards and I know they aren't shorted. The power supply voltages seem to be ok . What can I check on the Y SUS board to make sure it didn't get damaged when the buffers shorted initially? If anyone else has experience with this please chime in. Thanks.

[Paul678]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

Those 100v 3300 uf caps are bad on every one of these power supplies and very common failure.

the secondary voltages are running at 85 volts at these caps.

I have not had any other cap issues on this power supply other than these two large caps.

These are narrow caps and you have to watch when ordering replacements.

The buffers fail on these and can take out the y drive.

The best way to check these tvs is to unplug the upper or lower buffer board.

If the tv power supply was going into protect mode you can unplug one buffer at a time.

You can not check these like the l/g tvs, that, is you can`t unplug the y or z and have the tv power up. It won`t do anything unless all the boards are plugged in.

You can unplug the buffer boards and the tv will still power up.

I have found these in China on feebay for around 120.00 for the pair new.

These tvs have a great picture. (you have a good panel with multiple buffer ics)

This tv is very much worth repairing.

Yeah, as I've mentioned, I have already tested that my lower
buffer board is bad. Hopefully the Y-sus is still good. And
again, the two big caps (as well as pretty much every cap
on the board!) still tested good out-of-circuit.

Here's the only place that had this PS in stock:

http://www.iccfl.com/product_info.php?products_id=11166

What my fear is, is that I will order this, and it will show the
same symptoms, because there is some sort of missing
"turn-on" voltage that needs to come from another
board which is the real culprit.

But it seemed like there were healthy voltages going to
and from the other boards, so I'm not sure.

I just don't want to plunk down $126, plus some huge
shipping and handling fee from China to the USA, plus
another $67 for this:

http://www.ebay.com/itm/270950963043...84.m1438.l2649


....just to find out the bitch still doesn't work!

If I knew for certain that a $250 repair would
result in a working $450ish TV, then I'd do it.

OTOH, even if it didn't work, I could always
resell on Ebay, and get most of my money
back, but what a Goddamned pain the ass!

[Paul678]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

Check and replace any startup caps on the primary side.

Ok, did that. All the caps look good.

This meter is great. It seems very accurate. Unfortunately
for this case, the truth is a bit disappointing! haha

I'm tempted to use the o'scope to trace the voltage
from the Va and Vs back into the transformers, until
I find where the voltage is dropping. 89 Volts isn't
terribly huge, and my scope can handle it.

Problem is, I'll have to hang this huge power supply
board off the back of the TV, because not only must
I connect the main board and 120AC, in order to
turn-on the PS, but I need to be able to probe the
backside of this board.

Not going to be fun....... haha

[cadiman]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

Those 100v 3300 uf caps are bad on every one of these power supplies and very common failure.

the secondary voltages are running at 85 volts at these caps.

I have not had any other cap issues on this power supply other than these two large caps.

These are narrow caps and you have to watch when ordering replacements.

The buffers fail on these and can take out the y drive.

The best way to check these tvs is to unplug the upper or lower buffer board.

If the tv power supply was going into protect mode you can unplug one buffer at a time.

You can not check these like the l/g tvs, that, is you can`t unplug the y or z and have the tv power up. It won`t do anything unless all the boards are plugged in.

You can unplug the buffer boards and the tv will still power up.

I have found these in China on feebay for around 120.00 for the pair new.

These tvs have a great picture. (you have a good panel with multiple buffer ics)

This tv is very much worth repairing.

[tom66]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

Check and replace any startup caps on the primary side.

[tibimakai]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

That Russian meter looks very good.
http://www.dragonslairfans.com/smfor...p?topic=2651.0
It's like $60 too.

[Paul678]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

Go with NCC. Almost all plasma TV manufacturers seem to use them, even Panasonic. I think that is because the ESR is lower.

Ok, I just got my Russian Micro V4.0 ESR
meter, and when I measured these big
caps taken out-of-circuit, they were
both about ESR = 0.04 Ohms, 2800uF
each.

So these are both well within the +/- 20%
tolerance of these caps.

The third and fourth smaller caps were about ESR = 0.05 Ohms,
930uF, so both of them looked ok as well.

I probably have some other issue, if this meter is
to be trusted.

I checked all the diodes in the vicinity, including the
diodes mounted on the heat sink, and they all
appear good.

I also checked an 2SK3683 power mosfet, and
it was good.

Any ideas moving forward appreciated.....will have
pics soon....

[tom66]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

Ok, should I keep with the same brand that
failed in the TV, which is Nippon Chemi-Con:

http://www.ebay.com/itm/120875411381...84.m1438.l2649


Or should I go with Panasonic - EGC:

http://search.digikey.com/scripts/Dk...95677092970565


??????

Go with NCC. Almost all plasma TV manufacturers seem to use them, even Panasonic. I think that is because the ESR is lower.

[Paul678]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

These Vs caps supply the power to the plasma sustain boards, which pull peak 100A currents, so they are prone to bulging if poorly designed, but in general they do last a lot longer than the other caps. Paul linked a PDF which says these caps can bulge as a result of the bad buffer (this would be a dead short on Vs) but I find that hard to believe... Hmm...

Ok, should I keep with the same brand that
failed in the TV, which is Nippon Chemi-Con:

http://www.ebay.com/itm/120875411381...84.m1438.l2649


Or should I go with Panasonic - EGC:

http://search.digikey.com/scripts/Dk...95677092970565


??????

[tom66]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

Make that 3 big caps like i said. The smaller one between them looks suspicious too, and even if it isn't blown now, it'll go soon because it's right next to that heatsink just like the big ones. If the two big ones failed due to excess heat, the smaller one doesn't have much life left in it either.

These Vs caps supply the power to the plasma sustain boards, which pull peak 100A currents, so they are prone to bulging if poorly designed, but in general they do last a lot longer than the other caps. Paul linked a PDF which says these caps can bulge as a result of the bad buffer (this would be a dead short on Vs) but I find that hard to believe... Hmm...

[Th3_uN1Qu3]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

My plan: get the two big caps from Digikey:

Make that 3 big caps like i said. The smaller one between them looks suspicious too, and even if it isn't blown now, it'll go soon because it's right next to that heatsink just like the big ones. If the two big ones failed due to excess heat, the smaller one doesn't have much life left in it either.

[tom66]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

That sounds fine. Bulging caps could cause spikes in the supply voltage so it might explain why the buffers died.

[Paul678]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

Ok, so I used this testing method:

https://cdn.badcaps-static.com/pdfs/...8a445601d2.pdf


And apparently, I have a bad lower buffer board. The top board
tested good, at least with the DMM.

From what I've read, the same exact two big caps will bulge, and
often will make Vs and/or Va too large a voltage, and this will
blow out either one or both of the buffer boards.

My plan: get the two big caps from Digikey:

http://search.digikey.com/us/en/prod...6809-ND/131655

Install them and verify the Va and Vs and good.

Then I will install only the top buffer board, to see if I get
the top half of the picture. This will hopefully verify that the
Y-SUS and X-SUS boards don't have any blown MOSFETs.

Only then will I order the lower buffer board:

http://cgi.ebay.com/ws/eBayISAPI.dll...tchlink:top:en


If successful, this would be my first plasma repair.

Thoughts?

[Paul678]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

s/c is technician shorthand notation: Means short circuit. Most diodes fail leaky or s/c.

Mouser is good - I used them before for plasma TV caps 250V 560uF that were difficult to source.

POWER OFF is used to safely discharge those big caps. I think it is a legal safety requirement. A Panasonic plasma I serviced had a very nice "high voltage" LED that would stay lit to warn you of this danger. It would glow for 20-30 seconds with no power.

Ok, so do you recommend that I just replace those big
caps first, and see what happens?

[tom66]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

s/c is technician shorthand notation: Means short circuit. Most diodes fail leaky or s/c.

Mouser is good - I used them before for plasma TV caps 250V 560uF that were difficult to source.

POWER OFF is used to safely discharge those big caps. I think it is a legal safety requirement. A Panasonic plasma I serviced had a very nice "high voltage" LED that would stay lit to warn you of this danger. It would glow for 20-30 seconds with no power.

[Paul678]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

I've never encountered a plasma display using 90V for Vs. Very interesting. Typically it is 180-215V. Those caps are under a lot of stress, they will cost probably $10 to replace, but they are not the only problem. Likely you've got a s/c diode on the PSU, someone had a Hitachi here with the same problem, I think.

POWER OFF is one of two things:
- Signal from PSU to mainboard warning of imminent power failure (loss of AC, enough power for 100ms maybe)
- Signal from mainboard to PSU telling PSU to discharge Vs caps (safety) - top right resistors and SCRs handle that

Probably second one, as AC CLOCK is enough for power fail detect.

Check POD_STBY and REC_STBY, and main supply rails.

What do you mean by "s/c" diode? Do you have the link to the
thread with the same problem?

Ok, so "POWER OFF" is a signal to turn the unit off...duh!

Here are the voltages:

Power Off:

AC_CLOCK = +3.3V
POD_STBY = 0 V
REC_STBY = 0 V
Vcc5.1V = 0 V

Power ON:

AC_CLOCK = +3.3V
POD_STBY = +4.7V
REC_STBY = +3.1V
Vcc5.1V = 5 V

Is Mouser the best/cheapest place to order these caps?
They are 3300uF, 100V, 105 deg C

[tom66]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

I've never encountered a plasma display using 90V for Vs. Very interesting. Typically it is 180-215V. Those caps are under a lot of stress, they will cost probably $10 to replace, but they are not the only problem. Likely you've got a s/c diode on the PSU, someone had a Hitachi here with the same problem, I think.

POWER OFF is one of two things:
- Signal from PSU to mainboard warning of imminent power failure (loss of AC, enough power for 100ms maybe)
- Signal from mainboard to PSU telling PSU to discharge Vs caps (safety) - top right resistors and SCRs handle that

Probably second one, as AC CLOCK is enough for power fail detect.

Check POD_STBY and REC_STBY, and main supply rails.

[Th3_uN1Qu3]

Re: Dude is bringing over a Hitachi P50S601 (plasma 1080)

The three caps next to the heatsink on the right side all look bulged. Definitely replace them. Those are Chemicons, but this is an older set and it's likely they have simply reached end of life given their position.