NeoGeoVA
Member
I am waiting on some replacement diodes, but as soon as those come in and I replace them, I will check again.
Dead WG K7193 Chassis
- Thread starter NeoGeoVA
- Start date
NeoGeoVA
Member
Ok, R103 was open. The chassis now has power, but it is in HV shut down. My B+ is at 160V. I checked the C36 caps and they don't appear to be bad, but I am going to replace it anyways. I also checked the shut down pot and it is fine. The two caps next to it are brand new and were replaced after the problems started. What other parts could be causing HV shut down?
NeoGeoVA
Member
The VR, flyback and HOT are good.
NeoGeoVA
Member
I have not tried this, but I will. If I do get static noise what would it mean? Ok, I see what it is testing.
if you get static that means that the flyback is powering the tube but something else is causing the shut down. I suppose it could in fact still be a bad flyback but its unlikely.
DONT leave the monitor powered up for very long with that shut down disabled.
Check the B+ if it stays up and let us know what it is.
DONT leave the monitor powered up for very long with that shut down disabled.
Check the B+ if it stays up and let us know what it is.
NeoGeoVA
Member
I'd pull the VR and make sure none of its legs are internally shorted. Did you lift the diode?
Theres a trick on the U5000's that allows you to run the b+ into a 120VAC light bulb to act as a load. If you could isolate the B+ output and drive a light bulb with it that would tell you if your issue is within the power supply. If it still drives at 159VDC powering JUST the bulb then the power supply section is suspect. If it drives the bulb at 120VAC then the deflection section of the board is suspect.
Theres a trick on the U5000's that allows you to run the b+ into a 120VAC light bulb to act as a load. If you could isolate the B+ output and drive a light bulb with it that would tell you if your issue is within the power supply. If it still drives at 159VDC powering JUST the bulb then the power supply section is suspect. If it drives the bulb at 120VAC then the deflection section of the board is suspect.
NeoGeoVA
Member
I replaced the VR this morning and none of the legs were shorted. I did lift the diode.
modessitt
Volunteer: Encyclopedia Submission Moderator
Start going over all of your traces in that area behind the flyback. You most likely have one that isn't making properly...
NeoGeoVA
Member
I have continuity across all traces. I also rechecked the HOT and there are no shorts.
Last edited:
modessitt
Volunteer: Encyclopedia Submission Moderator
Does your C36 say 612 (or .0061) or 432?
NeoGeoVA
Member
It says .0061
modessitt
Volunteer: Encyclopedia Submission Moderator
Okay. And when you lifted one end of the diode, the monitor didn't come on?
NeoGeoVA
Member
modessitt
Volunteer: Encyclopedia Submission Moderator
Okay. Start with the basics:
1) Look for any little cracks around the flyback. Do continuity checks between each leg of the flybacks and the farthest point on the same trace.
2) Check Q11 again (HOT). Black lead on the center leg and red lead on each of the other legs should give you a reading between .400-.700.
3) Check Q10, R89, R101 and any other big part on the chassis. Actually wiggle them while watching the solder underneath, as they may be a little loose and not look like it...
1) Look for any little cracks around the flyback. Do continuity checks between each leg of the flybacks and the farthest point on the same trace.
2) Check Q11 again (HOT). Black lead on the center leg and red lead on each of the other legs should give you a reading between .400-.700.
3) Check Q10, R89, R101 and any other big part on the chassis. Actually wiggle them while watching the solder underneath, as they may be a little loose and not look like it...
NeoGeoVA
Member
1. No cracks were found and had continuity between each leg and the furthest points.
2. Each of the other legs read .52
3. All parts tested good and no loose solder.
2. Each of the other legs read .52
3. All parts tested good and no loose solder.
modessitt
Volunteer: Encyclopedia Submission Moderator
Pull out your wallet. Sounds like it's time for someone else to look at it...
NeoGeoVA
Member
That's not something I want to hear this close to Christmas. Money's tight, so that won't be happening for a month or so. I have a working 25k7191 chassis that I checked values against and they are all very close. I'm so confused as to what the problem is. Well, thank you for everyone's help. Maybe I'll get lucky and stumble upon an answer.
