Odd cap in my wells gardner 7602 chassis. What do I do?

[midnightpulp]

Hey guys, thanks again for all your help in the past. If not for you, my Phoenix machine would be nothing more than a pile of electronic guts.

Anyhow, starting a new project trying to correct the flickering issue in my MVS cab. Figured a cap kit might do the trick. Replaced most of the caps, but then at the C57 spot on the board (cap map: http://www.therealbobroberts.net/k7000lyot.html), there's a 100uf 160v cap. The replacement cap as per Bob Roberts kit is a 47uf 160v value cap. Any ideas on what to do?

Much appreciated.

[SirPeale]

It sounds like someone swapped out that cap for the wrong value.  It's supposed to be the one you have: 47uf @ 160V (which often gets bumped up to 200V).

How have the rest of the caps gone?

[midnightpulp]

Smooth. Monitor fired up with no problems (still with the wrong cap in) but was still flickering. So I pulled it out and had another look and found that cap. Hope replacing that cap will do the trick. If I'm still experiencing flickering after a fresh cap kit, what do you think the problem could be?

Thanks for the quick reply.
 

[SirPeale]

That's a pretty important cap, so I bet it helps with a lot of issues.  Swap it and report back.

Also, check your B+ voltage and report that too.

[midnightpulp]

That's a pretty important cap, so I bet it helps with a lot of issues.  Swap it and report back.

Also, check your B+ voltage and report that too.

Will do.

[midnightpulp]

Seems to be running a lot better. There's a very mild flicker, but not as bad as before. I run the machine for a few hours tomorrow and report back. Oh, and I totally forgot how to check B+ voltage on this board. Does the positive lead go to one the legs on the white component on the far left side of the board? Also, the multimeter should be set to AC, correct? Did a forum search, and couldn't find anything. Thanks again.

[SirPeale]

Set your meter to DC.  Black lead goes to frame, red to the large resistor mounted to the frame.  Leg closest to the tube.

I would also go over as much of the chassis as possible and touch up as many solder joints as you can.

[midnightpulp]

Set your meter to DC.  Black lead goes to frame, red to the large resistor mounted to the frame.  Leg closest to the tube.

I would also go over as much of the chassis as possible and touch up as many solder joints as you can.

Let the game run in attract mode for a few hours. Just played a couple games on it. Everything looks fine. Seems after it warms up, the flickering decreases dramatically from not at all to very, very mild. Doesn't affect gameplay or the overall experience like it did before, flickering every few seconds.

Ran a voltage test and the reading came back at 124.5.

[midnightpulp]

Round 2 tonight. Same routine, let it run for about an hour before play. Didn't experience any flicker. So it looks like everything is good. Thanks for you help, Peale.