Dude is bringing over a Hitachi P50S601 (plasma 1080)

[Paul678]

The supposed Problem:

When turned on, only a horizontal line appears in the
middle of the screen, and then the line blacks out.

Sound is apparently ok.

He's willing to take $15.

I figure even if it's an expensive buffer or Y-sus
problem, I can still just sell the parts on Ebay.......

[tom66]

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

Buffer board probably. Shorted top buffer maybe.

Hitachi will probably be 1280x1080 - NOT true 1080p.

But probably good enough and 50" is a big screen size so should make up for it!

[Paul678]

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

Buffer board probably. Shorted top buffer maybe.

Hitachi will probably be 1280x1080 - NOT true 1080p.

But probably good enough and 50" is a big screen size so should make up for it!

It says here it's 1920 x 1080:

http://www.tigerdirect.com/applicati...687&CatId=3654


How much you think the buffer board will be?

[tom66]

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

It says here it's 1920 x 1080:

http://www.tigerdirect.com/applicati...687&CatId=3654


How much you think the buffer board will be?

Hitachi is extinct now, so probably pricey, but for $15 you're far off going wrong. In faulty condition it is worth at least four times that -and- he's bringing it around. I wouldn't refuse it.

[Paul678]

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

Hitachi is extinct now, so probably pricey, but for $15 you're far off going wrong. In faulty condition it is worth at least four times that -and- he's bringing it around. I wouldn't refuse it.

Ok, got the unit.

There appears to be either a power supply or main board issue:



The large caps (upper right side) close to the Va and Vs connector
appear to be bulging a bit:





And after disconnecting the X-SUS connector,
both the Va and Vs are only at about 4 volts
or so (panel says Vs should be 88.9V, and
Va should be 65.3V), and they do NOT
change with turning on the power. The
front red "standby" LED, and blue "power
on" LEDs work fine, as well as the "power
save" LED.

But the interesting thing is, is that a pin
labeled "POWER OFF" does NOT change
voltage, and remains at zero volts, even
though the front blue LED indicates "power
on":



The STB5V and AC CLOCK, etc., all appear to
have normal voltages.

This makes me think there may be an issue with the
main input board, where it is not sending the
turn-on signal to the power supply, so that the
Va and Vs remain low, so that there is only a
black screen.

Should I try bridging from the standby 5V to the
"power off" pin, using a 1.5k Ohm resistor?

Do you think I should replace those two
big caps?

Thanks in advance for any advice.....

[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.

[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.

[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)

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)

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?

[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?

[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.

[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)

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...

[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)

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)

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....

[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.

[tom66]

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

Check and replace any startup caps on the primary side.

[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.