Electronics > Repair

Sony PVM-1271Q

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loglow, can you verify something for me?  On the B board, at spot C124, do you have a polarized cap in that spot? I've attached an image and highlighted it green.  The board is silkscreened bi-polar, but I'm just double checking that I'm not crazy as I pulled this cap and the photo I took prior is obstructed by a wire.  :(  The attachment also shows the orientation I recorded.

should be a 10uf 25v per the manual

The schematic of the 1371Q shows this as polarized with positive going to the IC102 pin 4 which is what I'm tracing as well on the 1271Q board.


--- Quote from: loglow on June 07, 2023, 05:26:49 am ---
This makes me feel better about recapping my power supply board too.

--- End quote ---

I ended up doing this as I figured I was so deep in pulling this thing apart I might as well. 

Well, I recapped the whole rig except for a handful of bipolar caps on the Q board.  I am still getting the same issue with the curved screen as in the attached photo.

I will review all the posts above and walk through the circuit.  I have been testing voltages as outlined, but I've found all the RV's raise and lower voltages in/out of the TDA chip and Q806, so kind of hard to map to that.

UPin and NPin amps and phases all have SOME effect, the YBOW adjustment has little to no impact.

I did find that the IC501 and IC504 voltages are pretty spot on with the schematics.

I also want to hook up my oscilloscope, however I'm new at that equipment and have to identify the proper ground point so I don't ruin it.  I also don't have an isolation transformer so I'm being extra cautious.

Good pickup - replying quickly to confirm:
- I've gone back to my pre-recap photos and can see C519 is 1uf 50v BP; C818 is polarised

Just seeing your second reply with things for me to action; my thoughts below:

--- Quote ---My board also had a bipolar at C519, but the silkscreen is marked as polarized.
--- End quote ---
Stock capacitor in mine was BP

--- Quote ---The service manual lists C526 as a tantalum. It's not an electrolytic cap on my board either.
--- End quote ---
I can't find it in my photos but in my checklist I've physically ticked YES to putting in a 3.3uF 25v electrolytic in C526s spot.  Would be unlike me to desolder a tantalum in a recap job so I think it's fair to conclude mine had a 3.3uf 25v elec from factory. 

--- Quote ---Jeremybh1, you have C535 listed twice, once as a 100uF and then again as a 1000uF. My board had a 10uF in this spot. The funky service manual lists this as 100uF in one place and 10uF in another.
--- End quote ---
I can see this now and have triple checked - confirming 100uf 25v was there from factory and that is what I put in.

--- Quote ---Jeremybh1, you have C537 listed as a regular 2.2uF. My board had this spot not populated. It's also marked as bipolar on the silkscreen.
--- End quote ---
You're right - my spreadsheet lists it as per service manual however in my checklist it's not ticked.  Then saw in my photos nil component present from factory.  I have deleted this row from the spreadsheet. 

--- Quote ---I don't think my board had a bipolar at C818 either, but I'll have to double check. The silkscreen marking was polarized.
--- End quote ---
See previous reply confirming C818 should be polarised; the confusion came from the adjacent C519

--- Quote ---My board had an odd thing at C801: There was a 0.47uF film cap as expected, but there was also a 470 ohm resistor in series with a 2.2uF electrolytic cap, both of which were soldered in parallel to the film cap.
--- End quote ---
Yes my photos show a film cap and an electrolytic in parallel; I probably didn't document this on the spreadsheet but did tick it off as done. 

I've opened the latest supplied photo in full and it's more than a pin issue - I say this as my understanding was pincushion correct is last mile sort of thing; you don't have full horizontal deflection, far from it.  Sure the is pin cushion issues but why is the raster 3/4 wide


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