A500 issue - floppy drive dims monitor

[kirk_m]

Hi, I have a very nice condition PAL A500, with Rev6a, all stock, with original chips and no mods done to it. The only expansion it has is a 512K trapdoor RAM expansion. It works fine, but has an issue in that every time the floppy drive clicks, or other wise reads, the monitor dims. It dims rhythmically with the click of the drive when there is no disk inserted. I have tried several PSUs, including ones of new construction, but, the 500 does the same with all of them. My other A500s also do not have this issue with the same power supplies, so, I think we can rule out there being an issue with the PSUs themselves. Where should I begin to look to try to fix the issue?

Many thanks,

Kirk

[pyrre]

Hi, I have a very nice condition PAL A500, with Rev6a, all stock, with original chips and no mods done to it. The only expansion it has is a 512K trapdoor RAM expansion. It works fine, but has an issue in that every time the floppy drive clicks, or other wise reads, the monitor dims. It dims rhythmically with the click of the drive when there is no disk inserted. I have tried several PSUs, including ones of new construction, but, the 500 does the same with all of them. My other A500s also do not have this issue with the same power supplies, so, I think we can rule out there being an issue with the PSUs themselves. Where should I begin to look to try to fix the issue?

Many thanks,

Kirk

could be failing caps on the mainboard......

[giZmo350]

Hi Kirk, well, you don't state that you tried another floppy drive and/or cable, I know kind of obvious, but did you try another floppy drive/cable? I've heard of SMD caps going bad in floppy drives too (I don't believe there are any SMD caps in an A500). Just a thought.

[kirk_m]

Hi Kirk, well, you don't state that you tried another floppy drive and/or cable, I know kind of obvious, but did you try another floppy drive/cable? I've heard of SMD caps going bad in floppy drives too (I don't believe there are any SMD caps in an A500). Just a thought.

That's next on the agenda, for this weekend.  I'll have to open up another A500 and rob its drive to try it in this one.