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hey!
wouldnt be posting if i wasnt more or less at my wit's end here -
refurbing this machine - when i got it, it was having all kinds of problems so i took the logical first step with these type/era of recorders and re-soldered the motherboard to make sure all the channel/connector pins were making good contact. that seemed to pretty much get it going but some channels were still a bit quiet. i troubleshot them one at a time and decided to re-solder the connectors on the cards themselves, as well. since then i've been banging my head against the wall trying to figure out what the heck is going on:
when i turn the machine on, tracks 3, 5, 6, and 7, if in 'tape' mode, just slam the VU meter as if im putting in a super hot, fluttery signal. if i switch them to 'input' mode, they act normal. this problem travels with the card if i swap them around. if i bend the card a bit when its in the socket i can get it to hit a sweet spot and it acts normal, but i have to tweak it just right and if left alone it goes right back to acting screwy - pinning the VU meter all the way in 'tape' mode with the machine stopped and no signal passing through.
channels 1 and 2 work OK, but channel 1 will sometime do the abovementioned thing. channel 4 works fine and so does channel 8. ive been soldering and resoldering thinking i have to get the pins just right and occasionally it will work for a little while, but then other problems might ensue, such as not recording properly.
in short, there seems to be something terminally wrong with the card connectors or perhaps the relays? like i said, the problem travels with the card, but almost all of the channels seem to be at least mildly susceptible to it.
the service manual i have does not have the right schematic for the cards - its the one for the A8 and A8LR thats floating around the internet - so i cannot very easily scope whats happening/would just be prodding at random points in the circuit. i can locate the spot where the card receives signal from the heads, of course, but thats about it.
any thoughts?? anyone have a similar issue with one of these machines before? its driving me crazy
wouldnt be posting if i wasnt more or less at my wit's end here -
refurbing this machine - when i got it, it was having all kinds of problems so i took the logical first step with these type/era of recorders and re-soldered the motherboard to make sure all the channel/connector pins were making good contact. that seemed to pretty much get it going but some channels were still a bit quiet. i troubleshot them one at a time and decided to re-solder the connectors on the cards themselves, as well. since then i've been banging my head against the wall trying to figure out what the heck is going on:
when i turn the machine on, tracks 3, 5, 6, and 7, if in 'tape' mode, just slam the VU meter as if im putting in a super hot, fluttery signal. if i switch them to 'input' mode, they act normal. this problem travels with the card if i swap them around. if i bend the card a bit when its in the socket i can get it to hit a sweet spot and it acts normal, but i have to tweak it just right and if left alone it goes right back to acting screwy - pinning the VU meter all the way in 'tape' mode with the machine stopped and no signal passing through.
channels 1 and 2 work OK, but channel 1 will sometime do the abovementioned thing. channel 4 works fine and so does channel 8. ive been soldering and resoldering thinking i have to get the pins just right and occasionally it will work for a little while, but then other problems might ensue, such as not recording properly.
in short, there seems to be something terminally wrong with the card connectors or perhaps the relays? like i said, the problem travels with the card, but almost all of the channels seem to be at least mildly susceptible to it.
the service manual i have does not have the right schematic for the cards - its the one for the A8 and A8LR thats floating around the internet - so i cannot very easily scope whats happening/would just be prodding at random points in the circuit. i can locate the spot where the card receives signal from the heads, of course, but thats about it.
any thoughts?? anyone have a similar issue with one of these machines before? its driving me crazy
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