Sony Trinitron KV-M2120U wobbly vertical deflection - UK Vintage Radio Repair and Restoration Discussion Forum

Retrorepair · 7th Mar 2024, 9:44 pm

Hi all,

Me again with another Trinny that needs some love.

The picture is fairly randomly jumping about in a way that looks like the vertical deflection is about to fail but never does, just flickers in a random way.

I've changed all the caps in that area and reflowed it too, still happily doing it's riverdance.

Just wondered if anyone had seen this before on a BE-1 chassis?

I did have a lovely list of various Trinitron repair logs once but have sadly lost it.

Retrorepair · 8th Mar 2024, 1:48 am

Well the image looked like it was getting better, then it started expanding vertically and kept going until all it will now display is the attached. Still jumping about and I've really no idea what to look at. I've also now replaced the upc1488h (v deflection ic) and it's not helped

RadioRich · 8th Mar 2024, 3:53 am

Hello Retrorepair,
Yes Sony one my favorite All time Tv's I own and collect their stuf and was a factory warranty and sales and service shop for them .

Do you have a Schematic diagram ? if not here is a link for that set

https://elektrotanya.com/sony_kv-m21.../download.html

Sincerely Richard

Welsh Anorak · 8th Mar 2024, 11:48 am

A coincidence - just been to an elderly customer who not only has one but uses it daily!

To get to the fault. I'm not sure if it was the BE-1, but there was a small capacitor near the jungle chip that could leak and damage the board causing conduction and odd faults. Might be worth a look?

FIXITNOW · 8th Mar 2024, 1:19 pm

C808 47nf 250v comes to mind

Retrorepair · 9th Mar 2024, 10:04 am

Quote:

Originally Posted by Welsh Anorak

A coincidence - just been to an elderly customer who not only has one but uses it daily!

To get to the fault. I'm not sure if it was the BE-1, but there was a small capacitor near the jungle chip that could leak and damage the board causing conduction and odd faults. Might be worth a look?

Never seen this model before and I'm also in Wales so yes, I'd call that a big coincidence!

There was a 1uf 250v that had previously blown it's top, removed that and cleaned the area around it, it didn't seem to make any difference at all but then that looks to be part of the horizontal deflection anyway.

Retrorepair · 9th Mar 2024, 10:05 am

Quote:

Originally Posted by FIXITNOW

C808 47nf 250v comes to mind

C808 appears to be 0.068uf 250v on my schematic, I'll check it out anyway. I happen to have one handy if it tests bad.

Retrorepair · 9th Mar 2024, 6:34 pm

Well C808 is in fact 47nf, appears to read fine though.

Really struggling with this one, whatever has failed did so gradually but I can't find the culprit or even anything that looks different to what I'd expect. Starting to wondernif this poor old set may be headed for the scrap heap

Retrorepair · 9th Mar 2024, 6:55 pm

I'm thinking there's two issues here. The vertical deflection issue and the G2 is unstable. It'll turn on and show the image above, then it'll settle down and the deflection issue is the only problem, then it'll come back, some times it flickers between the two. It's maddening.

For giggles, I tried a LA7830 in place of the upc1488h and deflection was the same but the picture was green, not red. Why that happened I can't tell you.

Have to say though, it's really weird, partial vertical collapse in my experience has always folded the top over itself. This seems to be folding the top over the BOTTOM. When the G2 calms down, you can see the RGB lines usually at the top on the bottom? Also no change of input seems to make any difference to the image.

Retrorepair · 10th Mar 2024, 8:07 am

Ok so small update, I have a hunch.

I don't actually think the issue is to do with the vertical deflection IC at all, I think it relates to the jungle IC. A TDA2579A. This is what handles vertical height on this set as well as H/V sync. Now that the jumpy picture has failed all the way, sync seems to have followed as in this video (sorry, no idea how to embed links):

https://youtu.be/zjcX5YHnYP4?si=rmE5dV3dTbTYPxn0

So my attention will now be focussed on this IC and it's driving components.

Welsh Anorak · 10th Mar 2024, 10:24 am

As I mentioned earlier, there are some low value electrolytic capacitors around the jungle chip (ones you wouldn't expect to fail) that can leak and cause mayhem.

Retrorepair · 10th Mar 2024, 11:25 am

Yeah there's definitely some leakage around there, I've cleaned it up as much as I can, just now checking values are correct and if still the same I may just replace the TDA and go from there

Retrorepair · 10th Mar 2024, 11:53 am

Quote:

Originally Posted by Welsh Anorak

As I mentioned earlier, there are some low value electrolytic capacitors around the jungle chip (ones you wouldn't expect to fail) that can leak and cause mayhem.

You know I'm only in Denbigh, wondering how much it might cost me to get your expert eyes on this thing.

Station X · 10th Mar 2024, 1:08 pm

Your forum profile says you're in Essex?

Retrorepair · 10th Mar 2024, 2:19 pm

Yeah I've not updated it, moved here about 2 odd years ago (and not looked back to be honest).

Retrorepair · 10th Mar 2024, 2:21 pm

Had another quick look, the yellow area is where I think I should be looking, feel free to correct me.

I can't see anything short or open here, resistors read differently but not read them out of circuit. Maybe it'd be worth doing that.

After that I think the TDA will be getting swapped out.

JonSnell · 11th Mar 2024, 9:40 am

I seem to remember when at Redifusion, we had one with a similar issue.
Pretty sure the issue was solved after checking the frame feedback loop; pins 1 & 2 of the jungle chip. Pin 2 was receiving spikey noise from what I recall. Can't recall if it was the jungle chip or a related component, sorry.
Hopefully I am not having another "Senior Moment".

Retrorepair · 11th Mar 2024, 2:12 pm

That would seem to indicate the vertical frame IC was the issue if the problem was on pin 2. I've ruled that out but there are a couple of resistors in that path I can check out. I'd expect no deflection if the TDA was failed but it could just have failed in part of the die. As Glyn mentioned, these small caps leaking in that area could cause all sorts of headaches, I need to get methodical in my approach I think.

Retrorepair · 14th Mar 2024, 3:57 pm

I'm at a loss. Changed the TDA2579A, can't find any shorts or bad resistors, all caps in the deflection area changed, it's different.. but not really.

This is one that's eating my soul, it's driving me mad.

Retrorepair · 21st Apr 2024, 2:06 pm

Still stuck with this one. Anyone have any ideas or even better a spare BE-1 chassis?

7th Mar 2024, 9:44 pm	#1
Retrorepair Pentode Join Date: Apr 2019 Location: Denbigh, Wales Posts: 154	Sony Trinitron KV-M2120U wobbly vertical deflection Hi all, Me again with another Trinny that needs some love. The picture is fairly randomly jumping about in a way that looks like the vertical deflection is about to fail but never does, just flickers in a random way. I've changed all the caps in that area and reflowed it too, still happily doing it's riverdance. Just wondered if anyone had seen this before on a BE-1 chassis? I did have a lovely list of various Trinitron repair logs once but have sadly lost it.

8th Mar 2024, 1:48 am	#2
Retrorepair Pentode Join Date: Apr 2019 Location: Denbigh, Wales Posts: 154	Re: Sony Trinitron KV-M2120U wobbly vertical deflection Well the image looked like it was getting better, then it started expanding vertically and kept going until all it will now display is the attached. Still jumping about and I've really no idea what to look at. I've also now replaced the upc1488h (v deflection ic) and it's not helped Attached Thumbnails

8th Mar 2024, 3:53 am	#3
RadioRich Diode Join Date: May 2008 Location: Tacoma, Washington, USA Posts: 6	Re: Sony Trinitron KV-M2120U wobbly vertical deflection Hello Retrorepair, Yes Sony one my favorite All time Tv's I own and collect their stuf and was a factory warranty and sales and service shop for them . Do you have a Schematic diagram ? if not here is a link for that set https://elektrotanya.com/sony_kv-m21.../download.html Sincerely Richard

8th Mar 2024, 11:48 am	#4
Welsh Anorak Dekatron Join Date: Apr 2005 Location: North Wales, UK. Posts: 6,928	Re: Sony Trinitron KV-M2120U wobbly vertical deflection A coincidence - just been to an elderly customer who not only has one but uses it daily! To get to the fault. I'm not sure if it was the BE-1, but there was a small capacitor near the jungle chip that could leak and damage the board causing conduction and odd faults. Might be worth a look? __________________ Glyn www.gdelectronics.wales

8th Mar 2024, 1:19 pm	#5
FIXITNOW Octode Join Date: Feb 2007 Location: Ely, Cambridgeshire, UK. Posts: 1,976	Re: Sony Trinitron KV-M2120U wobbly vertical deflection C808 47nf 250v comes to mind

9th Mar 2024, 6:34 pm	#8
Retrorepair Pentode Join Date: Apr 2019 Location: Denbigh, Wales Posts: 154	Re: Sony Trinitron KV-M2120U wobbly vertical deflection Well C808 is in fact 47nf, appears to read fine though. Really struggling with this one, whatever has failed did so gradually but I can't find the culprit or even anything that looks different to what I'd expect. Starting to wondernif this poor old set may be headed for the scrap heap

9th Mar 2024, 6:55 pm	#9
Retrorepair Pentode Join Date: Apr 2019 Location: Denbigh, Wales Posts: 154	Re: Sony Trinitron KV-M2120U wobbly vertical deflection I'm thinking there's two issues here. The vertical deflection issue and the G2 is unstable. It'll turn on and show the image above, then it'll settle down and the deflection issue is the only problem, then it'll come back, some times it flickers between the two. It's maddening. For giggles, I tried a LA7830 in place of the upc1488h and deflection was the same but the picture was green, not red. Why that happened I can't tell you. Have to say though, it's really weird, partial vertical collapse in my experience has always folded the top over itself. This seems to be folding the top over the BOTTOM. When the G2 calms down, you can see the RGB lines usually at the top on the bottom? Also no change of input seems to make any difference to the image.

10th Mar 2024, 8:07 am	#10
Retrorepair Pentode Join Date: Apr 2019 Location: Denbigh, Wales Posts: 154	Re: Sony Trinitron KV-M2120U wobbly vertical deflection Ok so small update, I have a hunch. I don't actually think the issue is to do with the vertical deflection IC at all, I think it relates to the jungle IC. A TDA2579A. This is what handles vertical height on this set as well as H/V sync. Now that the jumpy picture has failed all the way, sync seems to have followed as in this video (sorry, no idea how to embed links): https://youtu.be/zjcX5YHnYP4?si=rmE5dV3dTbTYPxn0 So my attention will now be focussed on this IC and it's driving components.

10th Mar 2024, 10:24 am	#11
Welsh Anorak Dekatron Join Date: Apr 2005 Location: North Wales, UK. Posts: 6,928	Re: Sony Trinitron KV-M2120U wobbly vertical deflection As I mentioned earlier, there are some low value electrolytic capacitors around the jungle chip (ones you wouldn't expect to fail) that can leak and cause mayhem. __________________ Glyn www.gdelectronics.wales

10th Mar 2024, 11:25 am	#12
Retrorepair Pentode Join Date: Apr 2019 Location: Denbigh, Wales Posts: 154	Re: Sony Trinitron KV-M2120U wobbly vertical deflection Yeah there's definitely some leakage around there, I've cleaned it up as much as I can, just now checking values are correct and if still the same I may just replace the TDA and go from there

10th Mar 2024, 1:08 pm	#14
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,290	Re: Sony Trinitron KV-M2120U wobbly vertical deflection Your forum profile says you're in Essex? __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

10th Mar 2024, 2:19 pm	#15
Retrorepair Pentode Join Date: Apr 2019 Location: Denbigh, Wales Posts: 154	Re: Sony Trinitron KV-M2120U wobbly vertical deflection Yeah I've not updated it, moved here about 2 odd years ago (and not looked back to be honest).

10th Mar 2024, 2:21 pm	#16
Retrorepair Pentode Join Date: Apr 2019 Location: Denbigh, Wales Posts: 154	Re: Sony Trinitron KV-M2120U wobbly vertical deflection Had another quick look, the yellow area is where I think I should be looking, feel free to correct me. I can't see anything short or open here, resistors read differently but not read them out of circuit. Maybe it'd be worth doing that. After that I think the TDA will be getting swapped out. Attached Thumbnails

11th Mar 2024, 9:40 am	#17
JonSnell Hexode Join Date: Oct 2019 Location: Weymouth, Dorset, UK. Posts: 478	Re: Sony Trinitron KV-M2120U wobbly vertical deflection I seem to remember when at Redifusion, we had one with a similar issue. Pretty sure the issue was solved after checking the frame feedback loop; pins 1 & 2 of the jungle chip. Pin 2 was receiving spikey noise from what I recall. Can't recall if it was the jungle chip or a related component, sorry. Hopefully I am not having another "Senior Moment". __________________ Valve equipment repairs since 1968 https://jonsnell.co.uk

11th Mar 2024, 2:12 pm	#18
Retrorepair Pentode Join Date: Apr 2019 Location: Denbigh, Wales Posts: 154	Re: Sony Trinitron KV-M2120U wobbly vertical deflection That would seem to indicate the vertical frame IC was the issue if the problem was on pin 2. I've ruled that out but there are a couple of resistors in that path I can check out. I'd expect no deflection if the TDA was failed but it could just have failed in part of the die. As Glyn mentioned, these small caps leaking in that area could cause all sorts of headaches, I need to get methodical in my approach I think.

14th Mar 2024, 3:57 pm	#19
Retrorepair Pentode Join Date: Apr 2019 Location: Denbigh, Wales Posts: 154	Re: Sony Trinitron KV-M2120U wobbly vertical deflection I'm at a loss. Changed the TDA2579A, can't find any shorts or bad resistors, all caps in the deflection area changed, it's different.. but not really. This is one that's eating my soul, it's driving me mad. Attached Thumbnails

21st Apr 2024, 2:06 pm	#20
Retrorepair Pentode Join Date: Apr 2019 Location: Denbigh, Wales Posts: 154	Re: Sony Trinitron KV-M2120U wobbly vertical deflection Still stuck with this one. Anyone have any ideas or even better a spare BE-1 chassis?