mc300baud
Well-known member
ok, so i finally tracked this hum down to the a/r board in my Asteroids. i rebuilt it with a kit from Bob to help bulletproof it when i sell the machine. it didn't hum before i did the rebuild but now it does. i can swap in another a/r-01 (one that i haven't rebuilt) and the hum goes away.
the +5 on my humming a/r i can dial in right at 5v but the one that doesn't hum i can't get lower than 5.5v so i'm assuming it probably needs a rebuild as well.
looking over the humming a/r i found this:
the diode at CR2 looks to have little metal bubbles coming out one end and maybe the side. it also tests with almost no resistance unlike the one on my non-humming a/r. i'm assuming it's probably blown; would this be a likely source of hum? is there anything else i should be looking for that might be causing the hum? i've already checked over all my work and it looks good with no stray solder accidentally connecting traces.
my local electronics shop closed up a few months ago so now i have to go a ways out of my way to pick up parts but if ya'all think this is the likely culprit then i'll do it. i know i could order one from Bob but i don't have anything else i need at the moment and it would seem to be pretty expensive when i add on the shipping.
the +5 on my humming a/r i can dial in right at 5v but the one that doesn't hum i can't get lower than 5.5v so i'm assuming it probably needs a rebuild as well.
looking over the humming a/r i found this:
the diode at CR2 looks to have little metal bubbles coming out one end and maybe the side. it also tests with almost no resistance unlike the one on my non-humming a/r. i'm assuming it's probably blown; would this be a likely source of hum? is there anything else i should be looking for that might be causing the hum? i've already checked over all my work and it looks good with no stray solder accidentally connecting traces.
my local electronics shop closed up a few months ago so now i have to go a ways out of my way to pick up parts but if ya'all think this is the likely culprit then i'll do it. i know i could order one from Bob but i don't have anything else i need at the moment and it would seem to be pretty expensive when i add on the shipping.
