Hatsune Mike
Champion
Fixed!
This chassis was entirely missing the X capacitors in the primary section. Transplanted them from a dead parts chassis, and it's rock solid now. no more 60Hz ripple, no more switching power interference.
Original Post:
I'm stumped with this chassis. No matter what I've tried, there's some ugly noise on the screen. Specifically, there's some 60hz ripple at the top of the screen, but also a wavy interference pattern that looks like ~100KHz switching power supply noise. It's not the cabinet or game board, as other chassis on this setup don't have any problems.
I did manage to capture a picture of it where it's fairly clear:
Things I have tried:
* Re-capping (this is the first thing I did) including main filter cap
* Scope B+, ~14V unregulated and 12V regulated rails (the only noise present was normal, matched my other chassis)
* Replace RGB amplifier IC
* Replace deflection driver PLL
* Replace mylar caps near power supply
* Replace 74HC86 that is responsible for combining syncs and generating part of the blanking signal
* Replace two SOIC-8 op-amps on the underside of the PCB
* Replaced the entire flyback for lols
* Replaced neck board (this was really desperate)
* Replaced LM7812 that drives the 12V line (used for logic, RGB amp, etc)
At high resolution, the noise is still there, but is less obvious just due to the different scan rate.
I'm this close to just tossing it on eBay as partially working and getting it out of my life, but that'd be a shame. I'd rather get it working.
This chassis was entirely missing the X capacitors in the primary section. Transplanted them from a dead parts chassis, and it's rock solid now. no more 60Hz ripple, no more switching power interference.
Original Post:
I'm stumped with this chassis. No matter what I've tried, there's some ugly noise on the screen. Specifically, there's some 60hz ripple at the top of the screen, but also a wavy interference pattern that looks like ~100KHz switching power supply noise. It's not the cabinet or game board, as other chassis on this setup don't have any problems.
I did manage to capture a picture of it where it's fairly clear:
Things I have tried:
* Re-capping (this is the first thing I did) including main filter cap
* Scope B+, ~14V unregulated and 12V regulated rails (the only noise present was normal, matched my other chassis)
* Replace RGB amplifier IC
* Replace deflection driver PLL
* Replace mylar caps near power supply
* Replace 74HC86 that is responsible for combining syncs and generating part of the blanking signal
* Replace two SOIC-8 op-amps on the underside of the PCB
* Replaced the entire flyback for lols
* Replaced neck board (this was really desperate)
* Replaced LM7812 that drives the 12V line (used for logic, RGB amp, etc)
At high resolution, the noise is still there, but is less obvious just due to the different scan rate.
I'm this close to just tossing it on eBay as partially working and getting it out of my life, but that'd be a shame. I'd rather get it working.
Last edited: