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Repair Log - Sony PVM-2054

hatmoose

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This one is in absolutely stunning cosmetic condition - shame it doesnt work.

Im mainly writing this here so I dont forget for later.

As PVM's go the 2054QM (also called the PVM-1954Q in the USA) it's quite decent - full OSD, good geometry controls in the OSD, great selection of inputs. Its a fully capable PVM - The line count is a bit lower than some of the later models, 600TVL compared to 800TVL in the 20M4 - but I already have a BVM-E1E with 1000TVL for them thicc scanlines

Symptoms are that it powers on ok, OSD and white screen appears, picture very unstable and no inputs from external sources. After about 5 minutes of operation loses picture, front panel still responsive, neckboard still glows.

This looks a lot like a problem with the power supply - the 2054 has a strange power supply by modern standards but it was very well designed.

One of the big caps that feeds the +5v or +7v line is failing - when it drifts too far out of spec the safety cutoff circuit clamps it off before it can damage anything else. This was a very useful feature that sony helpfully removed from the L, M and N series PVM's that came afterwards so you see a lot of blown HOTs on later models but not so much on the 2054.
Eventually the cap will let go altogether - if it fails closed that will take out the +5v or +7v voltage reg IC, but that has not happened yet. replacing those voltage regulators is hard so best to change the caps while I still can

Fixing this sould be as easy as reconditioning the power supply.
Probe the +5 and +7 lines to find out which one is unstable and clamping - replace the failing cap in front of the associated voltage regulator IC on the G board.
 
I was going to carefully trace the faults in this power supply and surgiucally replace only the faulty components, but then I read the details I posted here and decided to recap the whole lot, pretty much every cap on this power supply is due for replacement by now.

2054QM "G" board (power supply) full recap list
1648894099402.png


Caps are on order from mouser, delivery to the antipodes in only 21 working days , will report back after that
 
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