WG k6100 - has chatter and neckglow but no picture

jehuie

Well-known member

Donor 2011
Joined
Sep 8, 2007
Messages
10,947
Reaction score
1,672
Location
Martinez, California
So I picked up a Gravitar with only about 300 plays on it. Beautiful machine. Plays blind. I can clearly hear the chatter going on and I've got neck glow.

I haven't done anything at all yet since I just brought it home. Where should I start? Should I just immediately order a full rebuild kit for the thing or is it likely still all ok other than some single failed component since it has such little use. Will the caps be dried out just because of time passing? Or are they likely ok with such low usage?

I haven't even checked the fuses yet so I probably should get my wrist slapped for posting this already....
 
Is the spot killer on? Sounds like the HV is dead. If the spot killer is off, then check the connections between the deflection board and the hv cage. Anyway rebuild that sucker.
 
Fuses are all good. Everything appears to be plugged in. Maybe I'll try swapping the HV cage from my Black Widow to see if that brings it to life.
 
RobotronJon, its a 6100. Full color :)

No HV diode inline with the flyback cup here. But yes, sounds like something wrong in the HV section. Maybe a bad flyback, check for cracks. There is a cap or two and a few transistors in there as well.
 
That's interesting. I just replaced one on a V2000 to fix it but I've worked on a bunch of k6100's and never even noticed an HV diode in there. Are you sure we are talking about the same monitor??
 
Screen or brightness adjustment? HV overvoltage trip adjust? Disconnected wire under the boots on the back side of focus block? Or the black wire? Try the simple/easy things first.
 
Screen or brightness adjustment? HV overvoltage trip adjust? Disconnected wire under the boots on the back side of focus block? Or the black wire? Try the simple/easy things first.

Ooooh, I forgot all about these having the overvoltage shutdown. That's adjusted inside the cage isn't it? And I think some don't have that feature. Unfortunately, I am going to have to pull the monitor out to get to all that stuff. It's really hard to work on while in this particular cabinet. But...at least it has the long extension on the connector so I can test it out easily without putting it back in!

I did try the screen adjustment...I thought that was the brightness. Is there another brightness adjustment somewhere?
 
Update...still read the previous post please though! :)

So I backed my Tempest up to the game so I could plug the monitor in just to be sure the PCB is working ok. It is....fun to see it playing, although it's sideways of course. But at least I ruled out a PCB problem. Doesn't look like I'mma have time to pull the monitor out tonight though. :(
 
Ooooh, I forgot all about these having the overvoltage shutdown. That's adjusted inside the cage isn't it? And I think some don't have that feature. Unfortunately, I am going to have to pull the monitor out to get to all that stuff. It's really hard to work on while in this particular cabinet. But...at least it has the long extension on the connector so I can test it out easily without putting it back in!
Get one of the Bob Roberts 6100 extension cables. Or get a bunch of wire and the connectors and build one yourself. They are lifesavers.

I did try the screen adjustment...I thought that was the brightness. Is there another brightness adjustment somewhere?
Screen is brightness.

I haven't done much with the HV section on these, but The Internet™ tells me that you can measure B+ on pin 5 of P900, it should be 180v, and there's an adjustment pot in the HV cage.

I would pull the cage and reflow the header pins first, but measuring/adjusting B+ would be the next step.
 
Finally got my repair kit from Bob Roberts and upgraded most of the components today. It's still not working though. I know the problem is in the HV power supply section because when I swapped one in from another game it worked fine. But when I measure the B+ at pin 5 I'm only getting 25 volts. I tried adjusting up the pot in the HV cage up by about half a turn and it still reads 25 volts rather than the expected 180V. I did swap the pot out as well just to be sure. I don't see an adjustment on this one for the HV cutoff so I think it does not have that feature.

Any helpful ideas out there guys? Thanks!

Edit: Oh yeah, I did reflow the header pins as well. I inspected the flyback and don't see any cracks or anything that would indicate problems.
 
Last edited:
Finally got my repair kit from Bob Roberts and upgraded most of the components today. It's still not working though. I know the problem is in the HV power supply section because when I swapped one in from another game it worked fine. But when I measure the B+ at pin 5 I'm only getting 27 volts. I tried adjusting up the pot in the HV cage up by about half a turn and it still reads 27 volts rather than the expected 180V. I did swap the pot out as well just to be sure. I don't see an adjustment on this one for the HV cutoff so I think it does not have that feature.

Any helpful ideas out there guys? Thanks!

Edit: Oh yeah, I did reflow the header pins as well. I inspected the flyback and don't see any cracks or anything that would indicate problems.

If you're feeling brave you can measure the other voltages around the HV circuit as shown on the Tempest schematics. Not sure what's in Bob's kit, but you've got a bunch of semiconductors in there (Q900-Q903 regulate B+ directly, and D901 and Zeners ZD901 and ZD902). Before that, there's also the 555 timer that gets everything started - check pin 3 for pulses.
 
Thanks....the parts that were replaced were:

C910, C909, C905, C914, C901, C902

R901, R907, R903

R918 (25k pot)

ZD902

Q901, Q902, Q903
 
I also bought Bob's "Additional parts upgrade kit" which I have not yet installed. The only additional parts for the HV section in that kit are resistors.
 
If you're feeling brave you can measure the other voltages around the HV circuit as shown on the Tempest schematics. Not sure what's in Bob's kit, but you've got a bunch of semiconductors in there (Q900-Q903 regulate B+ directly, and D901 and Zeners ZD901 and ZD902). Before that, there's also the 555 timer that gets everything started - check pin 3 for pulses.

I'll check the 555 timer....I need to figure out which pin I can get +5 on first for my logic probe though. :)
 
Ok, looks like there should be +5 at pin 8 of the 555 timer. But I'm not seeing anything there at all. Sounds like a good clue to me. I'm off to look at the schematics.
 
Ok, looks like there should be +5 at pin 8 of the 555 timer. But I'm not seeing anything there at all. Sounds like a good clue to me. I'm off to look at the schematics.

Ah, classic. From the FAQ:

Symptom: IC901; If No Input Voltages, Check:
• Q900 (red and black leads reversed)
• ZD901 (check voltage drop)
• ZD900 (shorted)

I hope it's one of those and not the chip, 'cause I've seen your soldering ; )
 
Back
Top Bottom