Sony PVM-1954Q retrace issue

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posted
17 years ago

Wed, Oct 4, 2006 5:16 PM

Recently got a sony PVM-1954Q that had some bad electrolytics in it.

I recapped the A board, (132 caps, I won't be doing that anytime soon again) fired it up and did the alignments according to the service manual (I have that as well).

The only issue that 'remains' is there are 3 lines, one each for the red, blue, and green guns at the very top of the picture. This is evident in all modes, 4:3, 16:9, and underscan. You cant 'see' it in 4:3 mode as it's at the very top of the display but it's there if you move the picture with the vertical centering.

Wave forms and voltages look normal on IC506, 502, Q507 and Q505.

Picture looks good. All other alignments appear to work correctly.

Just can't get rid of those retrace lines. They look abnormal when you use the 16:9 or underscan modes.

Anyone ever run across anything like this ?

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- Airioch
  
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posted
17 years ago

Thu, Oct 5, 2006 3:38 PM

Ummmm, yes, I actually replaced all the electrolytics in the chassis with the exception of one of them, C1515, there's some modification on the trace side of the board that's covering that particular cap.

Didn't replace any of the polystyrene or dipped mylar..

I'll poke around in that area of the chassis, so some resistance checks on the associated resistors..

Thanks for the reply..

airi-

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posted
17 years ago

Thu, Oct 5, 2006 6:46 PM

Removing and measuring the components in that area shows them all to be well within tolerance with one possible exception.

L515 as indicated on the schematic should be, at least according to what's on the paper, 12uH. Looking in the parts list only gives a sony part number, going by what's indicated on the schematic, L515 is way out of spec, I'm measuring 12.38mH (wavetek LCR55).

I'm hoping that it's a misprint on the schematic, that's a pretty large amount to be out, I'd expect more than a couple of retrace lines at the top of the display..

airi-