modessitt
Volunteer: Encyclopedia Submission Moderator
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 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...