Yesterday, I suddenly lost all the "flashy" playfield lights. I diagnosed the problem as a bad pin connection on the power supply board. I re-flowed the pins (for a second time-my soldering equipment and skills have improved dramatically since last time I did it) and flashy lights are working solidly again.
However,
Now my displays are all dim and have a flicker. I had turned down the 190VDC (controlled by pot) to about 175VDC because a tutorial I read suggested that it would extend the life of my displays (which are hella-expensive BTW). My first adjustment down over-shot 175VDC and I got a similar flicker until I tuned it in to 175, at which time everything was bright and steady.
I know I should have already replaced the capacitors (especially the 160 uf 250V behemoth that smooths out the 230VDC), but does this sound like it is probably caused by the cap going bad? I bumped the 190VDC back up to 190VDC and it tests out good with my DMM on the test points on the board. I re- re-flowed the connectors that supply 190VDC to the displays.
I tested all of the diodes in the high voltage bridge rectifier circuit and they all test OK. D9, however, which is somehow related to +190VDC circuit, reads about 600mV one way and 1800mV the other. Looking at the wiring diagram, I suppose I could be getting backward voltage through Q1, as they are in parallel. I happen to have a 1N4004 diode, so I will go ahead and replace D9 (or at least remove one end and test it out of circuit). I am not an electrical engineer, but I am working on my ability to read a circuit diagram.
R2 was apparently replaced by a previous owner. I don't get anything near 200k ohms (much lower), so I suspect that might be bad as well.
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