• Please review our updated Terms and Rules here

1988 Sony kv-p14d trinitron CRT repair

I've soldered through the entire neckboard and the SCART connector. It appears the SCART connection issues and the loss of blue issue are now solved!

With the image quality being as good as it is now, I notice that the ("dynamic?") convergence on the bottom 1/3rd is "1 pixel off" resulting in some reduced apparent sharpness as colors leakup and down of where they should be (I think focus is OK everywhere though, but that's hard to see when the convergence isn't perfect), likely the yoke not being 100% in the correct position yet (see previous pages). Perhaps due to all the Mighty Whacks to get the color going? :) I'm afraid I might make it worse rather than better though; I don't have all the required tools and it's been a fine art to get the yoke position as good as it currently is. But given that red appears to be a bit too high and blue a bit too low, it really does seem like a vertical yoke alignment issue. Perhaps when I feel brave I'll try and make it better once more. I have easy access to Amiga paint programs now so I can try to make some test image if needed.

Anyway, more important: the "RF tuning to Tandy" issue still isn't solved with the above, obviously. Any pointers on how to check if it's the AGC, the tuner box, or something else? For those who missed it: I can tune into the Tandy on a modern TV, but this 1988 Sony can't lock into it but I can get a very poor image if I stop the autotuning at the right moment.
 
Last edited:
I have the same issue with a Sega console using its RF connection, so the culprit really seems to be the TV here, not the Tandy console.
 
Last edited:
I have -thanks to all the Gotek and external floppy drive capabilities of my upgraded Amiga- found a way to present profi test patterns onto the monitor, so I'll attack the dynamic convergence as soon as the other issues are solved, being the inability to tune to RF channels and a deflection buzz from the speaker.
 
The buzz is not the speaker but the deflection circuitry. I'll just live with it.

I'm now diagnosing the tuner. 12V ok. Agc 9.44V. 5V absent. I'm studying the schematic to see if that makes sense.
 
No 5V seems normal, according to schematic not connected. Strange that it's still silk screened, but there is no leg protruding either.

After messing with the AGC trimmer, I can get a poor/unstable black&white or even color version and sound (still poor and unstable), but no lock. AGC still is 9.44V where there is no reception, and drops to 0V around the test console frequency.

So it seems to me that he can cycle through the frequencies and the AGC works, but he can't get a strong signal and can't lock. Broken tuner unit?
 
If I'd want to replace the tuner, according to the service manual it's an UV-617. Philips UV617?

Is there any reference list for compatible models?
 
Hmmm I'm not about to replace anything yet: I was measuring stuff, and suddenly it worked for half a minute! Locked signal and all. I can't repeat it however...The soldering on the pcb looks fine.

Edit: Upon further investigation, it seems to work fine after a cold start but quickly deteriorates after that. After a minute or so, the signal is too weak/dirty to get a lock.

Now how to solve this...
 
Last edited:
US Sonys of that era often had bad soldering on one or more coils in the IF section. On many sets, the IF circuit was in a metal box near the tuner. I've also seen bad soldering inside the tuner before, but that's not as common.
 
Thanks! This set has a metal box "tuner" and a metal box "VIF" which contains the AGC trimpot. I have a yet-to-be confirmed suspicion that touching the VIF box makes the signal drop away suddenly; if I don't touch it the signal sometimes drops away gradually. There's also a bit of circuitry surrounding the VIF box (such as a coil between two IF inputs to the VIF box...); it's small enough that I can just redo all those solder connections.

I don't spot any bad soldering connections on the main PCB. Are you proposing I try to open the VIF box and check inside for bad soldering connections?
 
Yes, the bad connections are often inside the VIF box if it's anything like the sets Sony sold in the US. It was one of the most common problem these sets had. Tapping on it with a screwdriver handle might make it come and go if that's the problem.
 
Fixed after resoldering everything inside the VIF box! You were exactly right. This TV set has taught me a lot by now...
 
You must log in or register to reply here.
Back
Top