Sony BVM picture wobbles on bright scenes

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brandon.arnold
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Sony BVM picture wobbles on bright scenes

Post by brandon.arnold »

Hi all. I've been troubleshooting an issue with a Sony BVM monitor.

When the image is bright (whether because I turn the brightness or contrast high, or because I turn it lower and the scene is on the brighter side), the image wobbles vertically and horizontally.

Here's some video (see the image change around 0:17): https://imgur.com/a/CRkRjkC

Things I've tried:
1. Getting savon-pat to recap all boards. (Note: though controversial to some, he doesn't recap everything; he only changes caps in his opinion are most important).
2. Adjusting the 2 knobs on the flyback--this did improve matters somewhat, but not fully.
3. Turning down the brightness/contrast. Unfortunately, this works, but it's too dark.

Is my flyback screwed? What could be going wrong?
DejahThoris
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Re: Sony BVM picture wobbles on bright scenes

Post by DejahThoris »

The filter caps should be replaced. Honestly at this point in time, you should just do the entire PSU board, the monitor is old enough for it.

Make sure you replace them with appropriate low ESR capacitors. It matters when it comes to filter caps.
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brandon.arnold
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Re: Sony BVM picture wobbles on bright scenes

Post by brandon.arnold »

DejahThoris wrote:The filter caps should be replaced. Honestly at this point in time, you should just do the entire PSU board, the monitor is old enough for it.

Make sure you replace them with appropriate low ESR capacitors. It matters when it comes to filter caps.
Hey there. Thank you for chiming in! Are the filter caps on the deflection board? Sorry for the basic question, but Googling didn't quite answer it.
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Re: Sony BVM picture wobbles on bright scenes

Post by DejahThoris »

brandon.arnold wrote:
DejahThoris wrote:The filter caps should be replaced. Honestly at this point in time, you should just do the entire PSU board, the monitor is old enough for it.

Make sure you replace them with appropriate low ESR capacitors. It matters when it comes to filter caps.
Hey there. Thank you for chiming in! Are the filter caps on the deflection board? Sorry for the basic question, but Googling didn't quite answer it.
They are the physically large ones. Quarter in diameter and larger.

Been a few minutes since I've had a Sony opened up, but I'm pretty sure they're on the power supply board.

If you let me know the model number I'll pull up the manual and can point you to the right locations.
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brandon.arnold
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Re: Sony BVM picture wobbles on bright scenes

Post by brandon.arnold »

Hi there, @DejahThoris. It looks like there is one such cap for the BVM-A32, on the G module (images below).

I'm looking into replacing these, and see a number of decent choices on DigiKey. That's 450 V and 330 uF aluminium electrolytic, with calipers measuring 1.39" Diameter and 1.65" of available height. I think the main concern I have is getting the contacts to fit directly through the holes on the PCB. None of those in the list have poles that truly match what I'm measuring. Do you have a recommendation for this?

Image
Image
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Re: Sony BVM picture wobbles on bright scenes

Post by brandon.arnold »

I just put in an order for a few with some help on Discord. Suffice to say I don't think those through-hole lead styles are manufactured any more, so I will probably need to figure out some mounting strategies for caps that don't exactly fit or sit flush, with the hole placements.
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Re: Sony BVM picture wobbles on bright scenes

Post by DejahThoris »

brandon.arnold wrote:I just put in an order for a few with some help on Discord. Suffice to say I don't think those through-hole lead styles are manufactured any more, so I will probably need to figure out some mounting strategies for caps that don't exactly fit or sit flush, with the hole placements.
You should be able to find some, look for "snap-in" rather than through-hole.
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Re: Sony BVM picture wobbles on bright scenes

Post by brandon.arnold »

DejahThoris wrote:
brandon.arnold wrote:I just put in an order for a few with some help on Discord. Suffice to say I don't think those through-hole lead styles are manufactured any more, so I will probably need to figure out some mounting strategies for caps that don't exactly fit or sit flush, with the hole placements.
You should be able to find some, look for "snap-in" rather than through-hole.
That's true, though at some point the design for snap-ins changed from the diagram on the right, below, to the "Standard" style on the left. I defy anyone to show any availability of the one on the right! SO I'm going to need to bend pins or use some retrofit mounting strategy.

Image
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Re: Sony BVM picture wobbles on bright scenes

Post by jd213 »

Don't think I've ever had any problems with lead spacing when replacing caps on a PVM with modern snap-in caps.
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Re: Sony BVM picture wobbles on bright scenes

Post by brandon.arnold »

jd213 wrote:Don't think I've ever had any problems with lead spacing when replacing caps on a PVM with modern snap-in caps.
Good to know! Thanks. I will expect it to go well, then.
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Re: Sony BVM picture wobbles on bright scenes

Post by DejahThoris »

jd213 wrote:Don't think I've ever had any problems with lead spacing when replacing caps on a PVM with modern snap-in caps.
Ditto. It's simply a non-issue.
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Re: Sony BVM picture wobbles on bright scenes

Post by brandon.arnold »

jd213 wrote:Don't think I've ever had any problems with lead spacing when replacing caps on a PVM with modern snap-in caps.
DejahThoris wrote:
jd213 wrote:Don't think I've ever had any problems with lead spacing when replacing caps on a PVM with modern snap-in caps.
Ditto. It's simply a non-issue.
Hey there @jd213 and @DejahThoris. I'd like to clarify something. When you say you "haven't had problems doing it" and it's a "non-issue," did you mean:

1. You never had to bend the snap-in leads because you were always able to find a perfect fit, or
2. You've had to bend these snap-in leads and it was super easy to do

I assumed you meant (2) before, which is what I did earlier on the BVM-D24 power board, and it did work fine. However after re-reading, I wonder if you meant (1). If so, may I ask (beg) either of you to search your cap distributor of choosing and share with me some capacitors at the voltages I am talking about (150 uF @ 450V or 330 uF @ 450V) with those lead spacings in the image above? Because I am very skeptical you will find it.

Backstory: I have a local retro electronics repair person doing this on an A32 board with a couple of snap-ins I purchased with the above specifications. Again, the snap-in type is not the same as the one that was manufactured on these power modules originally. The repair person, upon going to replace them, seemed super flustered and judgmental about my asking him to use these that don't fit. So I said I would go back and make positively sure I was right about the fact that these original capacitor lead spacings don't exist anymore.
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Re: Sony BVM picture wobbles on bright scenes

Post by jd213 »

Looking into it a bit more, you may be onto something, at least for some caps.

I've replaced some big caps on PVMs before, and their leads were snap-in and new ones from Nichicon didn't need to be modified in order to fit. But the biggest one on my 20L5 hasn't been replaced yet, and it's definitely not a normal snap-in (circled in blue):

Image

Not sure what kind this is. Press fit maybe? Does it look like yours? Doesn't look like Nichicon even makes those, at least in this size (330uf/450V). If it is a press fit, looks like only Kemet makes them in this size.

edit: I took another look at your photos, and it does indeed look like the same lead style. KMH would be a United Chemi-con cap, don't see any in that style: https://www.mouser.com/c/passive-compon ... series=KMH
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Re: Sony BVM picture wobbles on bright scenes

Post by brandon.arnold »

jd213 wrote:Looking into it a bit more, you may be onto something, at least for some caps.

I've replaced some big caps on PVMs before, and their leads were snap-in and new ones from Nichicon didn't need to be modified in order to fit. But the biggest one on my 20L5 hasn't been replaced yet, and it's definitely not a normal snap-in (circled in blue):

Image

Not sure what kind this is. Press fit maybe? Does it look like yours? Doesn't look like Nichicon even makes those, at least in this size (330uf/450V). If it is a press fit, looks like only Kemet makes them in this size.

edit: I took another look at your photos, and it does indeed look like the same lead style. KMH would be a United Chemi-con cap, don't see any in that style: https://www.mouser.com/c/passive-compon ... series=KMH
Thank you so much for sanity checking me on this, and looking into it! I came to the same conclusion. There are terminal codes, where VS is the new kind and LI is the old kind (you have in the blue circle) in the United Chemi-con KMH datasheet. And LI seems nowhere to be found.
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Re: Sony BVM picture wobbles on bright scenes

Post by jd213 »

Yeah, it looks like there's the KLA series from Chemi-con with those leads, but they're all Non-Stocked on Mouser and they only seem to go up to 250V: https://www.mouser.com/c/passive-compon ... Capacitors

Hope your repair guy is able to find something that works, I'm probably going to need to replace this big cap in my 20L5 someday myself.
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Re: Sony BVM picture wobbles on bright scenes

Post by jd213 »

Any updates? I found someone talking about the same type of capacitor leads on Digikey's forums, and one of the reps suggested quick disconnects:
https://forum.digikey.com/t/can-t-find- ... or/19332/3

Going to try ordering some of these myself along with a snap-in cap.
I also tried straightening out the leads on a smaller snap-in cap with pliers, seems like that would work as long as the spacing is about right.
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