WG 6100 jitters when it warms up.

Jlannoo

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Hi, My WG 6100 in My Tempest jitters when it warms up. It has the cage over the HV section. I installed a LV2000 as well as a capkit. I have not replaced the frame transistors yet.

One issue I can find is that the HV only reaches around 16,000v the B+ being like 165v. Would that cause it to jitter? Its like the screen shrinks and expands rapidly a small amount.


comments?
 
Try tapping on the pots on the Main game board. See if the jitters increase. Those are pretty flaky. I've had several Tempests do the same thing. My tech replaced all the pots on the board at the vector section and problem was solved. I could have done it but he found the problem and had the pots on hand.

You might also mark the position of the pots with a sharpie, TURN THE POWER TO THE GAME OFF, then rotate the pots back and forth several times to attempt to clean them. Put the pots back in their original position. Turn power to game back on, make final adjustments to pots using very small adjustments.

Report back with your findings.
 
I should have mentioned it. I did play with the pots. Freeing them up.. tapping. didn't have any luck. Its not jittering on a particular axis. Just enlarging and shrinking quickly. Seems random, its very minor if flipped on cold and increases as it warms. Its still playable but annoying as it gets pretty pronounced. My voltages seem ok? I thought they seemed low. The HV is cranked all the way and still only getting like 16,500v. I installed a new HV potentiometer thing. Same result.
 
Has your big blue in the power supply been replaced? I think a failing big blue can cause that symptom.
 
I just fixed one with the same problem. Replaced all caps in the HV cage. If you haven't already. That may also bring your HV back up too.
 
just turning those pots should be enought however sometimes it isnt and will require a shot of electrical contact cleaner..

I remember cleaning some slider pots on a neogeo gameboard and they where caked so bad I had to scrap the gunk off the contact area.
 
Double check for cold solder joints, would make sense since it does it after it warms up.
 
From Arcadegames:vectormonitor repair guide

After fighting a problem in the Atari "Tempest" for three days and
finding a silly mistake, I thought I should write to you. Wells_Gardner
Monitors #19K6101 use a 1.5-ohm 10-watt resistor in location R610-R710.
If you replace these resistors with standard wire-wound units, the
monitor will exhibit the "shakes" or "jitters" referred to in S*TJ, VOl.
4, No. 7 "Service Tips", but the symptoms will be misleading in that
R601 and R701 must be *Non-Inductive*. Please tell your readers about
this problem as Atari and Wells do not point out this requirement in the
parts listing, and only put down the initials, "N.I" on the schematic.
 
From Arcadegames:vectormonitor repair guide

After fighting a problem in the Atari "Tempest" for three days and
finding a silly mistake, I thought I should write to you. Wells_Gardner
Monitors #19K6101 use a 1.5-ohm 10-watt resistor in location R610-R710.
If you replace these resistors with standard wire-wound units, the
monitor will exhibit the "shakes" or "jitters" referred to in S*TJ, VOl.
4, No. 7 "Service Tips", but the symptoms will be misleading in that
R601 and R701 must be *Non-Inductive*. Please tell your readers about
this problem as Atari and Wells do not point out this requirement in the
parts listing, and only put down the initials, "N.I" on the schematic.

Why would anybody replace resistors with wire nuts if the board originally had resistors??
 
You should post a video if you can, but it sounds like you're referring to blooming (increasing/decreasing in size) and not jitter. That is most likely caused by low HV. Typically, blooming problems on my K6100s have been a bad Zener diode (I believe ZD902... and they seem to test fine w/ the DMM, but fail in use, especially when warm).

DogP
 
You should post a video if you can, but it sounds like you're referring to blooming (increasing/decreasing in size) and not jitter. That is most likely caused by low HV. Typically, blooming problems on my K6100s have been a bad Zener diode (I believe ZD902... and they seem to test fine w/ the DMM, but fail in use, especially when warm).

DogP


I will check everything that has been mentioned. It does indeed look like rapidly increasing and decreasing of size. It just doesn't shrink or enlarge a great deal. I've noticed since my earlier post that the screen always does this even at cold power up but until it warms a bit its very very minor.

The HV is indeed low unless you guys think 16,000v is enough. There are a few Caps that the rebuild kit doesn't come with. The two larger ones on the HV board.

I have ZD902, I'm gonna install it now and post back in a bit


Sorry I have been slow to respond, been so tired lately.
 
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16kV is definitely too low... assuming if you don't have 19.5kV, you don't have a B+ of 180V, so from the Tempest troubleshooting flowchart it says:

Change or make sure C901 and C902 are 100uF at 50 volts. Check for a leaky C905. If C905 is bad, also check or replace Q900, Q901, Q902, Q903. Also look for burnt (open or shorted) resistors R903, R904, R905, R906, or R907.

The FAQ also says:

R915 (open)
R922 (open or wrong value)
Q900 (emitter pin open)
Q902 (bad)
Q906; white and black leads reversed (scope pattern is wrong)
ZD901 (shorted)
IC901; if scope output is a little high, replace IC901
P900 (ribbon pin #7 broken)

Also, are you checking/adjusting HV w/ no input signal, like you should?

DogP
 
oh my lol I installed zd902 at d902. Thats why it didn't work the other night. My zd902 detonated. Seriously it vaporized I cant find it anywhere.

So Anyways I reinstalled the old d902 and replaced r907 and r902 as r902 had split right open. After that was done now I have a opposite problem. Anode voltage is at just under 30k and B+ has increased to a silly high amount. Around 300v or so. Also R918 ( the HV potentiometer) has no effect adjusting the the HV


Woot for dumb mistakes




16kV is definitely too low... assuming if you don't have 19.5kV, you don't have a B+ of 180V, so from the Tempest troubleshooting flowchart it says:

Change or make sure C901 and C902 are 100uF at 50 volts. Check for a leaky C905. If C905 is bad, also check or replace Q900, Q901, Q902, Q903. Also look for burnt (open or shorted) resistors R903, R904, R905, R906, or R907.

The FAQ also says:

R915 (open)
R922 (open or wrong value)
Q900 (emitter pin open)
Q902 (bad)
Q906; white and black leads reversed (scope pattern is wrong)
ZD901 (shorted)
IC901; if scope output is a little high, replace IC901
P900 (ribbon pin #7 broken)

Also, are you checking/adjusting HV w/ no input signal, like you should?

DogP
 
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I'm not really sure... from looking at the schematics, the first thing I'd probably check is Q906... I believe a bad 555 could cause high HV as well (and Radio Shack should have them if you don't have one laying around).

You might also want to try searching RGVAC or Vectorlist... it seems pretty common for people to accidentally replace D902 when they want to replace ZD902, maybe someone has detailed out exactly what blew when they did it.

DogP
 
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