david winter
Member
Hi,
I'm trying to figure out the possible cause this problem after doing the following:
- Full recap of the cpu board
- Full recap and rechip of the motor daughter board (all CMOS chips tested bad with my TL866-II).
- Replaced Q17 (BD679) which I suspected to be bad (didn't test well) but no changes before/after replacing.
- Checked regulators output voltages: all correct.
- Tested both CD4094 chips (ok).
- Cleaned keyboard and LCD pcbs which had light green gooey residue around wire connections
- Socketed the logic chips I replaced or tested.
As soon as I power the unit up, the electromagnet activates and engages the head block as in play mode, but the reel motors don't spin. If I put the unit in sleep mode, the electromagnet obviously releases the head block.
Altghough the Power button works, none of the Play, FF, Rev and Stop buttons seem to work.
There is no problem with the keyboard circuitry: I disconnected it and simulated the Power button press using a shunt, but no change (and so, no short with any other button).
I suspect the MAB8440 chip, but not sure.
Which brings one question: has anybody found a clue to dump the ROM of those MAB8440/8441 chips ?
Any ideas ? Thanks !
I'm trying to figure out the possible cause this problem after doing the following:
- Full recap of the cpu board
- Full recap and rechip of the motor daughter board (all CMOS chips tested bad with my TL866-II).
- Replaced Q17 (BD679) which I suspected to be bad (didn't test well) but no changes before/after replacing.
- Checked regulators output voltages: all correct.
- Tested both CD4094 chips (ok).
- Cleaned keyboard and LCD pcbs which had light green gooey residue around wire connections
- Socketed the logic chips I replaced or tested.
As soon as I power the unit up, the electromagnet activates and engages the head block as in play mode, but the reel motors don't spin. If I put the unit in sleep mode, the electromagnet obviously releases the head block.
Altghough the Power button works, none of the Play, FF, Rev and Stop buttons seem to work.
There is no problem with the keyboard circuitry: I disconnected it and simulated the Power button press using a shunt, but no change (and so, no short with any other button).
I suspect the MAB8440 chip, but not sure.
Which brings one question: has anybody found a clue to dump the ROM of those MAB8440/8441 chips ?
Any ideas ? Thanks !