WG6100 Spare Board (SP)

Issue: Wavy vectors on the small text. Blue 'Star Wars' logo and larger green scrolling text were fine.

What I tried:

Removed C603, C703 green box caps. No change

Replaced R607, R707 non-inductive resistors. No Change

Reflowed header pins, transistors, rectifier diodes. No Change

Replaced all electrolytic caps, replaced tantalum caps (upgraded to 1uf 50v). No Change

Swapped HV box with known good unit. No Change

Rebuild HV box (caps, large resistors). No Change

What fixed it:

Identified R602 piggybacked cap did not match the manual or 6100 FAQ. This is a first revision 85X0147 (no C). Since this revision does not have a space for C605, the cap is piggybacked onto the resistor at R602. In this case, a .005uf cap was used. I wanted to test if this cap changed the picture, so I removed the .005uf and put a 1uf in for testing. Picture distortion became exponentially worse. Same type of vector distortion in the letters, but much more pronounced and unplayable. So I knew this cap value impacts the vector issue I was having. On the right track. Replaced it with the correct .001uf value and picture was noticeably improved with almost no text distortion. Definitely playable and the average person probably wouldn't notice the minor amount of distortion left on the picture.

Update: I removed the cap from R602 to see if it made a change. Negligible difference, if any. Picture looks great so I'm calling this one fixed.

Here is what it looked like originally. A lot of the text vectors seemed to have waves in them.

This is the incorrect value cap. It is a .005uf, should be .001uf

I installed a 1uf cap to see what would happen. Vector problems got much worse, but it told me I was on the right track.

Installed the correct value .001uf ceramic cap, piggybacked on to R602.

Issue is about 98% resolved. I may come back someday and remove the cap altogether or try a lower value to get the last 2%.

This is my 'spare board' I bought off e-bay and just about replaced every component on it.

Here's what it looks like after I removed the piggyback cap at R602. Negligible difference. Looks good, call it fixed!