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Sony PVM-1271Q

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mattswensson:
Hello, I'm working on a recently picked up Sony PVM-1271Q.  It has been noted that the online service manual for the 1271/1371 is lacking some information - I'm specifically looking for the waveforms for this monitor so I can hook up my scope and see what's going on.  Does anyone have these waveforms available or should I expect them to be similar to another model that waveforms are available?  Service manual https://archive.org/details/sony_PVM-1271Q_Service_Manual

The problem this monitor is exhibiting is significant pincushion that the pots can't seem to rectify.

I've found that pin 13 of the TDA1082 (IC804) is running at 6.7V vs the 3.4v specified in the schematics which traces back to multiple places include Q806 (2SD1138) that is outputting about 37v vs the 35.1v noted in the schematic and Q807 which is showing 4v instead of 2.4v.  Interestingly when I test voltage on Base (Input) of Q807 (DTC124ES) where there should be 0v (but is showing 1.4v), the pincushion gets impacted in a positive way.

So I'm narrowing down to possibly Q807 needing to be replaced - unless i'm being fooled which is a definite possibility because, well, i'm no expert on this and am still learning.

Anyway, any help or additional literature is appreciated.

I plan to get an NTE2357 to replace the DTC124ES as I'm reading they are equivalent.

loglow:
Hi Matt,

I'm in a very similar situation! I have one of these with very bad vertical bowing that I can't correct, and I suspect it's due to a fault.

I probably won't be of much help to you, since I don't really know what I'm doing, but perhaps we can help each other out.

I'm frustrated that the available scan of the service manual is incomplete and appears to be a combination of several different versions of service manuals. For example, it doesn't appear to contain sections 3-3-1, 3-3-2, or 3-3-3 at all. It also contains two different variations of section 6. (Side note: Do NOT buy the service manual from ServiceManuals.net because they are just selling the incomplete one you can get for free from https://archive.org/details/sony_PVM-1271Q_Service_Manual so I'm filing a chargeback.) Edit: ServiceManuals.net is indeed selling an accurate scan (and nice quality too, superior to the version on archive.org) of the real service manual with part number 9-963-325-01. The problem is that this service manual appears to have a severe printing error affecting pages 23-46 and a huge amount of the content is entirely missing from it.

The first thing I'm planning to do is replace all the electrolytic caps on the D board, since that seems like low hanging fruit. The two parts lists mostly agree with each other, although there are two different values for C535. I'll have to check mine and see which value it is.

Anyway, here's my spreadsheet with all of the D board capacitors listed, and all of the differences between the two parts lists (this is the "Caps" sheet). Edit: The link below is now a sheet with all of the electrolytic caps (for all boards) listed.

https://docs.google.com/spreadsheets/d/1YE-vZhxJ-iNjr-vr_YdPARD5g_YhLzjlOWTg84AWAdU

The "Elects" sheet is a list of just the electrolytic caps that I'm going to replace first, including the part numbers that I picked on Digi-Key.

Best,
Dan

jeremybh1:
Figured I should chime in here - I run hobby business Full Service Recap in Australia.
I can see a USA model number but should be the same.
I have the SONY PVM-1371Q in my personal collection and decided to 'fully' recap it and document this on my Excel spreadsheet. 

I don't share these widely but the eevblog is a good crowd and you may access it here: https://1drv.ms/x/s!AsalaOQMQ1R_gitfDNBGHleKgRJS?e=Ce5jsJ

While I was liberal in replacing the 38 year old capacitors; I left some as stock on the input terminal side only.  Quite a few were 'dead' and some photos are available showing >40 ohms ESR or totally open. 
We know ESR is only one 'thing' in caps - if they are leaking current and saturating a transistor then things aren't switching properly. I say this as your stated bad vertical bow could be as simple as a bad TDA chip - just work your way back in that section and recap it if replacing the IC. 

mattswensson:
Thanks to both of you.  I'm in the middle of a full recap and realized that the schematics don't seem to call out the bipolar caps well (or I missed it).  So i'll be placing another order.  And I missed the cap on the tube neck.

So far, I've found one cap on D board that tested bad (C759), but will replace them all anyway and report back.

mattswensson:
Jeremybh1, your sheet for Deflection board shows bipolar at C519, C529 and C818.

My D board has a bipolar installed at 519 and 529 but does not at 818.
By board is also silkscreened bipolar at 529, but not 519 or 818

I'm inclined to put a polarized cap in 818 given that is what mine has currently.  Did yours have bipolars in all those spots?

I've run into other scenarios where a bipolar can be used in some cases, but think I will start with replacing what I currently have.  maybe my board rev is different?

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