Pioneer plasma turns off: update

"William Sommerwerck" wrote in news:gtkd6b$vvn$ snipped-for-privacy@news.motzarella.org:

I'd suspect caps in the housekeeping supply for the switcher IC/circuit.

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Jim Yanik
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DaveC wrote in news: snipped-for-privacy@news.sf.sbcglobal.net:

Low ESR is -good- for an electrolytic cap.

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Jim Yanik
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Uh, right. They were *high* ESR...

Thanks.

-- DaveC snipped-for-privacy@bogusdomain.net This is an invalid return address Please reply in the news group

So, hopefully, you replaced them all...?

-- W . | ,. w , "Some people are alive only because \\|/ \\|/ it is illegal to kill them." Perna condita delenda est

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DaveC wrote in news: snipped-for-privacy@news.sf.sbcglobal.net:

one other thing may be to measure the actual capacitance of each electrolytic cap;I've had some that measured much below their nominal rating.

and if -some- supplies are high,that could show that another one is being loaded and the PS is driving harder to pull it up,raising the other supplies in the process. Seen a lot of that in TEK WFM monitors.

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Jim Yanik
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In message , DaveC writes

You've missed a capacitor or an open circuit resistor in the PSU primary, specifically in the startup supply that feed an SMPS controller chip before the main PSU starts.

Check the high value resistors and the low value capacitors (usually under 100uF) in the primary circuits.

If you feel happy working on energised mains fed equipment then while the PSU is in the faulting state, check for voltages on the outputs (if you know the voltages expected then a bunch of LEDs with appropriate series resistors can be very useful for missing voltage checks)

Power cycle it and then check again.

Bets are that it's not one single PSU, but a couple or more possibly on the same board. Probably one of them isn't starting up correctly after being off for a few hours and/or cooling down.

That's within 1% and the accuracy of your meter comes into play as well at that sort of margin, I'd expect the voltages to be +/- a couple of percent minimum, possibly up to 10% and still be OK so I don't think there's anything to be concerned about there.

Go back and check the rest of the components one at a time.

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Clint Sharp

ernight rest, it will shut off

will

w

To the O.P:

In case you haven't noticed it, at

a-display

there is an offer of a manual for this thing for sale, $7.50. I don't know anything about how trustworthy the seller is, and have no connection with the site. It does accept paypal and credit cards.

Note that the URL does not have any line breaks in it, they are just an artifact of the way I am posting this.

There are also two avenues you might want to try without spending money:

1) typically, if you lower the input voltage to about 100-105 volts, turn-on trip circuits can be overcome.

2). You might want to try the following experiment:

A. Leave the thing in standby for at least 8 hours. B. Remove power by disconnecting from AC, not with the on-board switch. C. Delay at least 2 minutes. D. Re-apply power and turn on with the remote. E. If it works, shut it off with the remote after no more than 30 secs. F. Delay at least 5 mins, then see if it will turn on again.

If it still works, you could easily be looking at a software problem that arises only after hours of idle operation. The complete manual just might tell you that you need at least a revision X board at position Y.

Good luck.

Hey Dave, i've been trying to fix a hitachi 50" plasma with no VS and Va (No pic audio works fine though). Initially i thought the power supply was bust, i googled Vcago and Vcego on a hunch ( 2 pins on a connector coming from logic pcb) and that led me to

This guy, John, seems to have a lot of experience on plasmas. Maybe you could post one in there and see what he says. Turned out that a blown panel driver on my Hitachi lower Y-buffer pcb was ordering logic to shut down panel supplies in ps. Jango

Thanks for the pointer. But this is just a "technical manual", not service (ie, repair) manual. Contains installation (including mounting on a stand), picture adjustments, etc.. Nothing re. module or component troubleshooting.

This site is not alone; most of the sites with plasma manuals have this one, and they all describe is as "service manual". I ask for a peek at the table of contents before paying, and so far have come up with no service manual.

Thanks for the other ideas. I'll see how they pan out.

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DaveC
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Thanks, Jango. I'll check it out.

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DaveC
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On Sat, 9 May 2009 22:50:11 -0700, DaveC put finger to keyboard and composed:

The manual you have is probably this one:

FWIW, Pioneer's part number for that manual appears to be ARP2981.

Here is a collection of Pioneer service notes:

I suspect that you may have a power sequencing issue.

FWIW, here is an ECO (Jan 25, 2001) that describes such an issue (page

227).

================================================================== SYMPTOM 1 PDP repeats turning on and off.

CAUSE 1 Power circuit will be reset because the secondary circuit rarely works before the primary circuit works normally when the power turns on.

SERVICE Change of two resistors in Main Power Assy; AWR1077.

Ref CURRENT PARTS CO NEW PARTS

• # SYMBOL/DESCRIPTION PART NUMBER DE PART NUMBER SYMBOL/DESCRIPTION A 1 R3107 RD1/2PM473J RD1PM153J R3107 A 1 R3108 RD1/2PM563J RD1PM153J ==================================================================

It appears that the above ECO calls for changing R3107 from 47K 1/2W to 15K 1W, and R3108 from 56K 1/2W to 15K 1W.

FWIW, the service manual for the PDP-502MX has a section (page 58) that talks about power sequencing:

- Franc Zabkar

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Hi Franc, Yes I have the technical manual which, sadly, is not the service manual. And regarding the ECO describing the 2 resistors, I've changed them. No joy.

The 502MX manual does have a section on power sequencing that is very good. If I had such a description for this monitor (V401) I'd have known long ago what the problem was, exactly.

Thanks,

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