Bad_Hambre
Enthusiast
I have picked this bad boy up, with the intent to test all my monitors and to use it on any new sets I might get. Started off with just testing my 19" inch CR31 tube I was using as a donor along with a WG K7000 chassis. Anyways, I was able to set both HTR voltage and G1 voltage, but ran into problems when trying to set the G2 cutoff for Green. I was able to set cutoff for Red/Blue. I also tested the other funtunality "cant remember which one exactly" and when making adjustment to one, it was moving one of the other colors. Figured since G2 cutoff is messed up, it might explain why other needles were moving as well.
So i did the next thing which was to give it a reflow at the back of the board. Then I ordered a cap kit, I also ordered and replace a few resistors that look like they were in some bad shape. I checked both the manual, and matched the physical color bands to verify the values were correct. But now I can't set up none of the cutoffs for any of the colors. I've asked around for anything else i might have missed. Was given some good suggestions like reflowing the joints on those dials, which i have now done. Was also suggested to check the resistance on the dials as i turn them. Have not done that one yet, but seems a bit suspect that those dials would all just fail.
What are more suggestions? The service manual has this
One G2 control fails to adjust properly.
1. Collectors of Q2, Q3, and Q4 with scope for typical square wave. A straight line indicates a bad transistor.
2. G2 controls R49, R50, and R51.
3. Transistors Q5, Q6, Q7.
4. Multiplex generator voltages and waveforms.
5. ICIA, ICIB, IC2C, ard IC2D.
All G2 controls fail to adjust properly.
1. 12BH7A tube V1.
2. Transistor Q1.
3. Rectifiers Dl thru D4.
4. Transformer T1.
5. Capacitors C11 and C12.
6. Resistors R41 and R43.
7. Multiplex generator waveforms.
8. IC1A, IC1B, IC2C, and IC2D.
I think I replaced the resistors that it mentions. I will check again next chance i get to work on it.
And I replaced those caps as well. Polarity is good from what i cabn see.
So i did the next thing which was to give it a reflow at the back of the board. Then I ordered a cap kit, I also ordered and replace a few resistors that look like they were in some bad shape. I checked both the manual, and matched the physical color bands to verify the values were correct. But now I can't set up none of the cutoffs for any of the colors. I've asked around for anything else i might have missed. Was given some good suggestions like reflowing the joints on those dials, which i have now done. Was also suggested to check the resistance on the dials as i turn them. Have not done that one yet, but seems a bit suspect that those dials would all just fail.
What are more suggestions? The service manual has this
One G2 control fails to adjust properly.
1. Collectors of Q2, Q3, and Q4 with scope for typical square wave. A straight line indicates a bad transistor.
2. G2 controls R49, R50, and R51.
3. Transistors Q5, Q6, Q7.
4. Multiplex generator voltages and waveforms.
5. ICIA, ICIB, IC2C, ard IC2D.
All G2 controls fail to adjust properly.
1. 12BH7A tube V1.
2. Transistor Q1.
3. Rectifiers Dl thru D4.
4. Transformer T1.
5. Capacitors C11 and C12.
6. Resistors R41 and R43.
7. Multiplex generator waveforms.
8. IC1A, IC1B, IC2C, and IC2D.
I think I replaced the resistors that it mentions. I will check again next chance i get to work on it.
And I replaced those caps as well. Polarity is good from what i cabn see.