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No Picture
Repair of: Monitor (Wells Gardner WG6100)
Repair Type: Part
Status: Fixed
Contributed by: Arcadenut
My friend Dan brought his Gravitar over and it was playing blind.
You can hear chatter, see neck glow, but there is no static on the screen.  The monitor was essentially dead.
See Diagnostic steps for full solution.

Diagnostic/Repair Steps

The following steps were taken to either diagnose or to repair the PCB/Part/Game: 
Verified that the game played blind.
11/4/2012 10:10:18 PM
Powered the game up, and verified that the game actually did play blind.
I also pulled the board and put it in another Gravitar and it played just fine with a perfect picture.  So I was able to rule out the PCB at that time.
I also verified all voltages within the cabinet and they were spot on. 
Visual Inspection of the Monitor
11/4/2012 10:11:01 PM
I pulled the monitor out and visually inspected the monitor.  I found the following issues:
  • Fuse F101 blown
  • Fuse F600 blown 
 So it's time to rebuild the monitor.
Rebuilding the Deflection Board
11/4/2012 10:19:41 PM
To rebuild the deflection board I :
  • Replaced all Electrolytic Caps (C800, C801, C802, C803, C100, C101)
  • Diodes D100, D101, D102, and D103
  • Upgraded the Deflection board with the LV2000 kit
  • Replaced Fuses F100,  F101, and F600
No B+ on Pin 5 of J900
11/4/2012 10:32:32 PM
After rebuilding the Deflection board, I put the monitor back in the game and fired it up again.  Still no static on the screen and when I measured the B+ at pin 5 of J900, I get 0 Volts.
So it's time to rebuild the HV section.  This can be a pain at times.
So here is what I replaced so far: 
  • Caps  C902, C901, C914, C909.
  • Q900 (Transistor next to Focus control, outside of cage)
  • Q905 (Transistor on outside of cage near tube) 
I didn't have caps for C905, or C910, so I ordered those along with other parts that I might need to replace (NE555, ZD900, ZD901, etc...) 
Still No B+ or HV
11/4/2012 10:39:17 PM
So I replaced the Flyback.  This had zero effect, so it's probably ok.  If you can avoid replacing the Fly back, I would recommend it, as it's a major pain in the ass to do.
So after doing some more research, I ordered more parts and will be replacing them.
I could do tests, but I'm too chicken to stick my hand in the HV section of the monitor while it's turned on, so I'm going with the "replace the most likely part" and see if it fixes it route.   Can be a bit more expensive, but less shocking :) 
R920 is Crispy
11/4/2012 11:21:04 PM
Well, the first time through I missed the fact that R920 was a bit crispy.
So I pulled it and test it, it measured out at 1.5MOhm instead of 1.5KOhm.  The resistor is 1/2W and all I had on hand was, a 1.5KOhm  2W resistor, so I used that.
I also replaced C905, C910 and the NE555 at IC901  since I got my parts in.  Still no changes.  One other thing to note is the Spot Killer light flashes on and off.  Hopefully it's not related and I can work on that issue later if I need to.
11/24/2012 9:50:03 AM
Well, I found the reason why I wasn't getting any High Voltage...
User error.  I missed a connector (P101) when hooking everything back up.   If you're not getting voltage from the Deflection board, you're not going to get HV.
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Parts Replaced

The following parts were replaced:
Part Name 
Part Location 
Original Part Number 
Price Paid 
Substitution Parts 
Reason For Replacement 
ExpandDIODED100S5A2$2.00 None
ExpandDIODED101S5A2$2.00 None
ExpandDIODED102S5A2$2.00 None
ExpandDIODED103S5A2$2.00 None
ExpandFuseF1015A @ 250V$2.00 Defective
ExpandFuseF6003A @ 250V$2.00 Defective
ExpandFuseF1005A @ 250V$2.00 Preventitive
ExpandLV2000 UpgradeDeflection Board $35.00 Preventitive
Expand2N3716Frame2N3716$2.50 Preventitive
Expand2N3716Frame2N3716$2.50 Preventitive
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Other Repair Logs

These repair logs are related to this repair log.
Tempest Plays Blind Turned my Tempest on the other day and I got no picture.  Was able to coin up the game and play blind. Rebuilt the monitor.  Upgraded it to an LV2000, replaced Caps, and Diodes D100-D104. Fixed
Game is restricted to the lower right corner of the Screen. After rebuilding my 6100 for Tempest, I encountered this new issue where the you could see the full game, but it was in the lower right corner of the monitor.  It appears to have full deflection, but it doesn't fill the entire screen.
Had a bad LV2000.  The nice thing about the LV2000 is they will replace it for free if it ever goes bad.  Just luck of the draw that I had a bad one.  Still highly recommended.
The main problem was is it wasn't putting out the proper voltage to the HV section.  The HV section needs +26V DC and -26V DC,  the the LV2000 was only putting out the +26V DC so the monitor was drawing the entire image in the lower right corner.
So if you don't have an LV2000 installed, then the problem is in the Low Voltage section and either fixing the low voltage section, or by upgrading to an LV2000 it will fix this issue.
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