K7500/7400/U5000/2000 remote board traces the same?

modessitt

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K7500/7400/U5000/2000 remote board traces the same?

I know there are pot size differences between these monitors, but the connector is the same and the board looks the same, even if they are call P718, P790, P804, etc. Can I change one type to another simply by changing the values of the pots (or removing the H-Hold pot if necessary)?

I have a K7500 here with vertical deflection loss. Found R402 smoked. Replaced it and now have R303 smoking on power up (even after replacing it). Changed out the flyback and D302, but no change. I noticed it had a P718 (U5000) remote board plugged into it instead of the P804 (K7500) remote board.

The main differences between the two are:

H-Pos
K7500 - 10k
U5000 - 20k

V-Pos
K7500 - 2k
U5000 - 10k

H-Hold
K7500 - not installed
U5000 - 5k

Contrast
K7500 - 1k
U5000 - 10k

Brightness
k7500 - 50k
U5000 - 100k

Just for fun, I found a K7400 remote board (P790) lying around and tried it, but got no better results. Differences between the 7500 (P804) and the 7400 (P790) are as follows:

H-Pos
K7500 - 10k
K7400 - 20k

Contrast
K7500 - 1k
K7400 - 10k

It seems the K7400 remote board SHOULD work enough to give me a full picture if this was in fact the problem.

I have not yet capped the board, as I wanted to stop the smoking resistor first, and I haven't been able to find a shorted or blown capacitor in this circuit which might be letting the smoke out of this.

Day's over for now, but figured I'd put it out there so I have something to mess with tomorrow. If I can just change the two pots to make it a K7500 remote board, then at least I'll know that isn't the problem. I just want to make sure the traces are the same between the two and it isn't trying to send the vertical signal through the wrong pot...
 
I'd suggest you change your vertical IC and at least the 600 series electrolytics. The IC is what is more than likely causing your resistor to burn up, since it just feeds the supply voltage to this IC. Usually the surrounding electrolytics cause strain on the IC and cause it to fail. Although it could have had unnecessary strain placed on it from using the wrong remote board. I don't think a remote board would directly cause that resistor to burn up.
 
Well, I plan to replace the caps anyway. I'll check that IC, though...
 
the resistors make a difference on the remotes too. I tried a direct pot swap from a 7500 to a U5000 and it let out a very sour smell. once I got a good donor board off a junk K7500 and swapped the little resistors on it too, it worked fine.

I'm sure you already knew that, but the booze is telling me you only said anything about the pots. :)
 
Well, the remotes were not the issue.

I checked the vertical IC (U601) against another I had, and they tested the same, but I changed it out anyway and now have a full pic and no burning parts. I'm using the P790 remote as that is the closest to what is needed.

Capped it and have a nice pic....
 
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