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.
To the O.P:
In case you haven't noticed it, at
there is an offer of a manual for this thing for sale, $7.50. I don't
anything about how trustworthy the seller is, and have no connection
the site. It does accept paypal and credit cards.
Note that the URL does not have any line breaks in it, they are just
artifact of the way I am posting this.
There are also two avenues you might want to try without spending
1) typically, if you lower the input voltage to about 100-105 volts,
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
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
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
arises only after hours of idle operation. The complete manual
might tell you that you need at least a revision X board at
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.
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.
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
=================================================================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
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
Please remove one 'i' from my address when replying by email.
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.
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