Commodore 1702 Brightness/Contrast Issue

Torin

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I have a 1702 monitor that I've recapped/reflowed. The monitor has beautiful colors and an amazing picture however the monitor shows a white screen when it is supposed to be black. Specifically, when a screen transitions from one colorful screen to a black screen, the screen will go bright white. It's hard to explain but it is as if the brightness drifts way up and then will settle down and look correct again.. I tested and replaced the contrast, brightness, sub brightness pots and tested resistors around it extensively. I'm not sure if anyone here has much experience working on one of these but just thought I'd put it out there for maybe some ideas. Thanks.
 
Look at the DC restoration/clamp circuits?

EDIT:
If you have an oscilloscope check the waveforms around IC201.
If you don't have a scope then measure the DC voltages on IC201.

I'd start with a waveform at pin 8.

But don't measure directly on the IC pins...you might short them out.
Find a convenient test point or a component leg to clip to.
For example, measure pin 8 over on C201.
 
Last edited:
I do have a scope but I'll have to dust it off. I appreciate the direction and will report back.
 
NFS (not for sale), but I might have been the only one who ever received complete capacitor kits for the 3 famous Commodore monitors:
  • 1702
  • Daewoo 1802
  • Goldstar 1802
All 3 of these kits are unopened, but contain valuable sheet that has 100's of capacitors and pcb location identifiers on each.


commodore-monitor-cap-kits.jpg
 
NFS (not for sale), but I might have been the only one who ever received complete capacitor kits for the 3 famous Commodore monitors:
  • 1702
  • Daewoo 1802
  • Goldstar 1802
All 3 of these kits are unopened, but contain valuable sheet that has 100's of capacitors and pcb location identifiers on each.


View attachment 636035

Jesus. I knew it was bad, but wow. Seeing those kits really brings it home.
Remind me not to EVER recap a C= monitor. :ROFLMAO: :dead1:
 
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