Sony KP-57WS510 bad convergence

[Mrx3750]

I found a Sony KP-57WS510 last night. Surprise surprise the convergence is shot.

So I went online and looked up the cost of a convergence repair kit. Almost $80.00. So after I got done laughing, I decided to see about testing the components and find out what failed and just replace that. From what I can tell, this bastard uses IC's, fusable resistors, and pico fuses! Kinda like Sony built in as many failure points as they could.

Right now I'm working on getting the board that the convergence IC's are on out of the TV. I have everything disconnected except the wire leading from the flyback to what I guess is the tripler. I'm not sure if I can just pull it out, or if there's some trick I need to know.

Don't have pics yet. Can get them if necessary. Was planning on getting them once I got the board out.

[RON_CET]

Re: Sony KP-57WS510 bad convergence

lift the rubber cap from the HV lead @ tripler then push down lead wire @ tripler and rotate 90 degrees

[Mrx3750]

Re: Sony KP-57WS510 bad convergence

Thank you RON CET. That did it!

Okay attached is a pic of the convergence board, and a shot of the area that I believe I need to focus on.

The convergence IC's are STK392-560 IC's

I see various ELNA branded capacitors near the IC's. Far as I know, ELNA caps are all right.

There are 6 big resistors under the heatsink, 120 ohm, unsure of wattage rating.

So I'm wondering where to start, and if it's possible to test the convergence IC's with my multimeter to see if only one is bad.

Also wondering where the pico fuses are.

[RON_CET]

Re: Sony KP-57WS510 bad convergence

most common would be replacement of both convergence ic's also check all those pico fuses,I think there the yellow(I attached your drawing and circled them) I think there's total of 4 also can't tell from the photo but those 120 ohm resistor look to be have been exposed to stress they look discolored,I also have the service manual if needed

[Mrx3750]

Re: Sony KP-57WS510 bad convergence

Service manual would be nice.

I'm seeing the IC's on Ebay for next to nothing, but I would bet they're Chinese knockoffs.

[RON_CET]

Re: Sony KP-57WS510 bad convergence

Service Manual attached

[truep]

Re: Sony KP-57WS510 bad convergence

I had a Hitachi with the same problem. I replaced the IC's and several Low ohm rest1sors and it worked fine. Be sure to use flame proof resistors here as they are designed to blow in the case the IC shorts without causing a fire. As I remember they wer all under 1 qhm.

[Mrx3750]

Re: Sony KP-57WS510 bad convergence

Yeah I am familiar with replacing convergence parts. Done it a few times. problem is that I need to do this on the cheap.

Suppose the issue is just a blown pico fuse? or a bad resistor?

[Mrx3750]

Re: Sony KP-57WS510 bad convergence

Okay, I tested the big 120 ohm resistors out of circuit, and they all read fine.

I also tested (in circuit) all the orange pico fuses that I could find and they tested fine.

So my last suspect is the convergence IC's themselves. Can I test them with my multimeter to see if they're bad?

[Mrx3750]

Re: Sony KP-57WS510 bad convergence

Well the Service manual happens to be almost useless. There's no specific section related to convergence issues, which is funny seeing as how that's what most often fails in these behemoths.

However I've been researching, and it seems there may be two more pico fuses on another board. What if I find that just those fuses are bad?

[RON_CET]

Re: Sony KP-57WS510 bad convergence

Those other 2 pica fuse your referencing to are on the "G" board see attached
If one or both of theses fuses are open naturally would suspect convergence IC's cause these fuses are connected to the +/- 22 volt rails to convergence ic.

[Mrx3750]

Re: Sony KP-57WS510 bad convergence

Thank you. I found two orange pico fuses on the G board, and testing them in circuit, I got 0 ohms.

Not sure where to proceed from here.

[RON_CET]

Re: Sony KP-57WS510 bad convergence

I would measure the +/- 22 volt supply to both convergence ic as i have circled in red and just make sure none of the 4.7 ohm resistor which are circled in green are not open from your yoke return to convergence ic if all that appears good i would then replace both convergence ic

[Mrx3750]

Re: Sony KP-57WS510 bad convergence

The 4.7 ohm resistors, judging by what I can make out on that schematic are those all the blue ones that are under the convergence IC heatsinks?

[RON_CET]

Re: Sony KP-57WS510 bad convergence

yes

[Mrx3750]

Re: Sony KP-57WS510 bad convergence

All right. I'll desolder those and test them out of circuit. When I do that I'll reply with what I found.

Thank you again RON CET

[Mrx3750]

Re: Sony KP-57WS510 bad convergence

All right I've been thinking.

Those resistors under the heatsink, they're all wired up in parallel in several banks. If one failed, that whole bank would fail. Testing in circuit across all the resistors basically nets me 0 ohms, so I surmise that the resistors are fine. I guess I'll know more if and when I can get those IC's, but it makes sense to me.