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 Post subject: Sony Indextron KV-4SV2 Repair
PostPosted: Jul Wed 13, 2022 12:20 pm 
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Hi!

I am currently trying to give a new life to a nice little Sony KV-4SV2. The service manual is freely available online

The first thing I did is clean the boards and replace the high temp capacitors that were leaking (all of them).

I then realized that the previous owner might have done repair as it appear some parts on the D1 board are missing. Obviously Q1501 is not there. The same for other SMD components next to it. See picture.

I cannot determine what is missing based on the service manual and the annotations on the PCB have been damaged by the cap leak. Any one has picture of the board or any info that could help ?

Many thanks


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Jul Wed 13, 2022 1:01 pm 
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Those parts may not have been installed at the factory, Do they show up in your schematic for this model? Sony was known for leaving parts off for different models but using the same board. What problem are you having? When these caps leak they open the feedthroughs that allow the traces to pass through the board from front to back. Also any coils or small transformers that the capacitor electrolyte touches will probably be open from corrosion. I used to deal with quite few sets from this vintage that used these nichicon and rubycon anhydrous series that leaked. Mitsubishi, sony used these caps extensively and many boards had corroded traces. These caps were made from 1989- late 1995 and they all will leak. You will have to verify all traces for continuity where the caps leaked and possibly replace parts damaged by the electrolyte. Used to spend many hours fixing open traces and changing caps on these boards when these sets were still feasible to repair.


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Jul Wed 13, 2022 1:21 pm 
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Thanks for the reply. I used this version of the service manual https://archive.org/details/sonykvx370schematics
It applies to KVX-370, KV4-SV1 and KV4-SV2 so normally should be applicable for my model. Here is the diagram including Q1501.
Actually I noticed his was missing while trying to understand why IC1501 doesn't have VCC voltage,


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Jul Wed 13, 2022 1:52 pm 
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Its hard to say what parts are missing without having the board in front of me to trace visually or ohm out. I havent seen one of these rare sets for many years in front of me and only seen two in my career for repair. Maybe someone has a photo of their board? Otherwise you will have to use a meter and visually trace everything out in the area to verify against the schematic. I know its a pain, but the board looks to be in repairable shape. Things always get fun then caps leak....I still work on sony video walkmans and some 8mm camcorders and they are loaded with leaky capacitors, some of those boards are beyond repair from open traces.


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Jul Wed 13, 2022 3:20 pm 
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Indeed my hope was to have someone that would still have a picture of the board.
The board was not too damaged I cleaned everything with IPA. I don't know if I can something else to clean it more.


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Jul Wed 13, 2022 5:48 pm 
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decoder_82 wrote:
Indeed my hope was to have someone that would still have a picture of the board.
The board was not too damaged I cleaned everything with IPA. I don't know if I can something else to clean it more.

Cleaning the ENTIRE pcb with deoxit d50 will help neutralize the capacitor acid that has seeped everywhere and under surface mount parts. Wash the board in it and allow it to dry, nothing will be hurt. Try posting this at videokarma if you don't get any hits here. These sets are relatively rare and most guys here specialize in much older sets. I have worked on them because I worked professionally in tv/electronic repair daily until 2015. The last one I saw was 2008. Most people dont know about the capacitor problems of electronics of this vintage. the worst thing to do is just "run it". Doing that accelerates the corrosion and chances of destroying a part not easily replaceable. Spent many hours at the bench fixing mid 80's-early 90's equipment with leaking capacitors.


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Jul Thu 14, 2022 4:51 am 
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Thanks I will try deoxit d50 on the board. I just have to figure out if we can get this in Europe.

I have in the meantime purchased the Japanese version of the service manual.

Looks like there are some differences in the circuit compared to what I saw in the US version (which claims to also cover KV-4SV2). Q1501 is there too so I am going to find a replacement. Really strange why would someone remove a part like this and leave all the leaky caps there ?


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Jul Thu 14, 2022 5:24 am 
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I've fixed about a dozen of these.

The electrolyte can cause the solder to become so weak that parts just fall off the board. I clean them with an ultrasonic cleaner, then check over the entire board under strong magnification. You will probably have to scrape clean and resolder a number of parts. Remove the flyback before you wash the board. While it's out, check to see if electrolyte has seeped under the metal shield around the flyback.

2 out of the last 3 of these I worked on had bad CX22011 power supply control ICs. I think electrolyte seeps into the IC over time. I was able to buy replacements on Aliexpress.


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Jul Thu 14, 2022 6:01 am 
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ac wrote:
I've fixed about a dozen of these.

The electrolyte can cause the solder to become so weak that parts just fall off the board. I clean them with an ultrasonic cleaner, then check over the entire board under strong magnification. You will probably have to scrape clean and resolder a number of parts. Remove the flyback before you wash the board. While it's out, check to see if electrolyte has seeped under the metal shield around the flyback.

2 out of the last 3 of these I worked on had bad CX22011 power supply control ICs. I think electrolyte seeps into the IC over time. I was able to buy replacements on Aliexpress.


Thanks for the advice. I already did the recap / cleaning but maybe I should clean more in depth. ultrasonic cleaner sounds indeed a good approach. I guess I would also need to remove the caps for the ultrasonic cleaner ?

This is my first time working on this unit, I repaired many TV and monitors but nothing small like this. This is really crazy how things are packed.

Do you recommend recapping all boards ? From what I saw most leaks where on the D boards with the Elma high temp capacitors. On the other board saw no sign of leakage.


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Jul Thu 14, 2022 3:06 pm 
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An ultrasonic cleaner shouldn't hurt the caps. Simply washing it and scrubbing it is probably good enough, but I like to be thorough.

It's only certain types of caps that leak, but there are some on most of the boards. It's the long life, high temperature ones that were defective. There are a few hidden inside the big metal shield on the bottom board. Most of them are on the power supply board, and deflection board. Spot cleaning is fine for the other boards.


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Jul Thu 14, 2022 6:24 pm 
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Location: Middletown NJ
decoder_82 wrote:
ac wrote:
I've fixed about a dozen of these.

The electrolyte can cause the solder to become so weak that parts just fall off the board. I clean them with an ultrasonic cleaner, then check over the entire board under strong magnification. You will probably have to scrape clean and resolder a number of parts. Remove the flyback before you wash the board. While it's out, check to see if electrolyte has seeped under the metal shield around the flyback.

2 out of the last 3 of these I worked on had bad CX22011 power supply control ICs. I think electrolyte seeps into the IC over time. I was able to buy replacements on Aliexpress.


Thanks for the advice. I already did the recap / cleaning but maybe I should clean more in depth. ultrasonic cleaner sounds indeed a good approach. I guess I would also need to remove the caps for the ultrasonic cleaner ?

This is my first time working on this unit, I repaired many TV and monitors but nothing small like this. This is really crazy how things are packed.

Do you recommend recapping all boards ? From what I saw most leaks where on the D boards with the Elma high temp capacitors. On the other board saw no sign of leakage.

Change only those funny elna caps, the others should have a little more time and only replace if you have a problem. None of those others should fail in this manner. These caps used to leak in their VCR's too. They used them in the power supply. If you want to proactively replace any caps replace the ones in the vertical output circuit. When these go bad they usually take out the vertical output IC.


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Jul Fri 15, 2022 4:57 am 
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Thanks for the replies. Already replaced all caps on the deflection and power board.
Will check again the big metal shield on the bottom board. At first glance it was looking fine but will do a more in depth check.

I ordered a replacement for Q1501. Will take a while to get it (ordered from AliExpress).

In the meantime, I will continue to check for open traces and try to determine why CX22011 doesn't receive any voltage.

What is the best approach ? I was thinking to look at the service manual schematic and check continuity between components one by one. and re flow solder when needed.


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Jul Fri 15, 2022 2:09 pm 
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decoder_82 wrote:
Thanks for the replies. Already replaced all caps on the deflection and power board.
Will check again the big metal shield on the bottom board. At first glance it was looking fine but will do a more in depth check.

I ordered a replacement for Q1501. Will take a while to get it (ordered from AliExpress).

In the meantime, I will continue to check for open traces and try to determine why CX22011 doesn't receive any voltage.

What is the best approach ? I was thinking to look at the service manual schematic and check continuity between components one by one. and re flow solder when needed.

Pretty much what you have to do....follow the print and look for the missing or open parts to replace. Try disconnecting VCC from the IC and see if it comes up, the IC could be loading it down.


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Jul Sun 17, 2022 5:52 am 
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Thanks I will do that, it will take a while to check all the deflection and power board but that's the best approach.
Testing the TV powered on is not so easy as all the wires are very short and test points are hard to access


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Jul Sun 17, 2022 3:18 pm 
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For testing, you can run it with the top button panel unplugged. This will give you better access. Before you do, turn the power on, then unplug the power from the set. It will remember it was turned on when you reapply power.


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Jul Mon 18, 2022 5:49 am 
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ac wrote:
For testing, you can run it with the top button panel unplugged. This will give you better access. Before you do, turn the power on, then unplug the power from the set. It will remember it was turned on when you reapply power.


Oh nice tip !
To troubleshoot power supply can I also leave the CRT neck board unconnected (wrapped around something to avoid accidental short) and deflection coils also unconnected ?


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Jul Fri 22, 2022 5:42 am 
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On bigger TV, I know power supply be can tested independently by connecting a light bulb to have a load similar to what the tube and deflection would absorb.
I was wondering if a similar approach might work on such small set to be able to troubleshoot the power supply part alone.


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Aug Fri 05, 2022 1:14 pm 
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Some update: I finally received the part for Q1501.
Now it is in place, I have also repaired a some traces that were damaged.

Unfortunately I still get very low voltages almost everywhere on the board. CX22011 has 0.7v as VCC which is not enough.

Any advice I could look next ?


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Aug Fri 05, 2022 3:10 pm 
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You may need the deflection coils connected in order for the power supply to work right.

A VCC reading of 0.7V suggests that there is a silicon junction connected between VCC and ground.
It could be a damaged IC, transistor, etc. Maybe there is a short connecting VCC to a place it isn't supposed to be connected to.
You may have to start disconnecting things that VCC is connected to in order to track it down.

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Tim
It's not the Destination, It's the Journey.


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 Post subject: Re: Sony Indextron KV-4SV2 Repair
PostPosted: Aug Sat 06, 2022 5:28 am 
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Yes indeed some TV won't start without the deflection coils connected. Usually the workaround is to connect resistor with value close to the ones of deflection coils. Here is was connected when I measured.

Previous post suggest that CX22011 is known to fail on those TV. If I don't find other potential root cause I will explore this.
I keep this a last thing to check. Removing it will probably mean destroying it. There is much corrosion a around the legs, I will probably have to cut them and carefully remove one by one to preserve the PCB traces and pads.


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