Telefunken AL15A Autolocator : defect
Verfasst: Montag 24. Oktober 2022, 12:36
Dear forum members,
I'm new here, my name is Ralph, and I'm a 39 years old technician from Belgium.
I own, service and operate various tape machines in my collection, amongst which a Telefunken M15a.
I hope it is OK if I write this in English. Feel free to reply in German, I can read it.
Right now, I'm in the process of repairing an AL15A Autolocator for a Telefunken M15a. I've been stuyding the schematics for this device for the past few days now, and starting to get a grip on how it's build.
I hope there is someone here who could help me trace down the fault.
I've build a custom power supply for the +12V, +5V, -5V and -9V. All voltage levels are withing +-5%.
When enabling the power supply , without any other external signals (all external input signals ZWIMP, RICHTG and GM38 are at this stage connect to GND), nothing happens. the displays do not light up.
Sometimes, when connecting the plug St12 manually to the power supply, the bottom left LED segment Ph1 partially lights up (some segments are lit).
I've scoped the I8008-1 processor, and it tells me that it is in a STOPPED state. (s0 = H, s1=H and S2 = L). the 2 differential clock inputs are present at 600kHz, the READY input is H, the Sync signal is present at 300kHz and the INTERRUPT input is L.
A courious thing about the 8008 is that, in order to get it started after powerup (processor is in STOPPED mode at this time), it needs a short Interrupt pulse to start working. I probed the INTERRUPT input, and I get a very brief pulse shortly after start-up. Either this pulse is not in the correct timing (TBD) or, the processor is defective or the software is defective. Or there is another reason... I've checked all resistors and transistors, and replaced all the tantalium caps already, but no luck.
Is there anyone on this forum who might help me bring this device back to the living?
I have all the schematics, including the one for a special PCB BC-ZS1, that is not mentionned in the original schematic, which I can post, including measurements and additional routing.
the sn# of this AL15A is 9, so I believe it's an early build one.
Any help would be highly appreciated!
Thanks, Ralph
I'm new here, my name is Ralph, and I'm a 39 years old technician from Belgium.
I own, service and operate various tape machines in my collection, amongst which a Telefunken M15a.
I hope it is OK if I write this in English. Feel free to reply in German, I can read it.
Right now, I'm in the process of repairing an AL15A Autolocator for a Telefunken M15a. I've been stuyding the schematics for this device for the past few days now, and starting to get a grip on how it's build.
I hope there is someone here who could help me trace down the fault.
I've build a custom power supply for the +12V, +5V, -5V and -9V. All voltage levels are withing +-5%.
When enabling the power supply , without any other external signals (all external input signals ZWIMP, RICHTG and GM38 are at this stage connect to GND), nothing happens. the displays do not light up.
Sometimes, when connecting the plug St12 manually to the power supply, the bottom left LED segment Ph1 partially lights up (some segments are lit).
I've scoped the I8008-1 processor, and it tells me that it is in a STOPPED state. (s0 = H, s1=H and S2 = L). the 2 differential clock inputs are present at 600kHz, the READY input is H, the Sync signal is present at 300kHz and the INTERRUPT input is L.
A courious thing about the 8008 is that, in order to get it started after powerup (processor is in STOPPED mode at this time), it needs a short Interrupt pulse to start working. I probed the INTERRUPT input, and I get a very brief pulse shortly after start-up. Either this pulse is not in the correct timing (TBD) or, the processor is defective or the software is defective. Or there is another reason... I've checked all resistors and transistors, and replaced all the tantalium caps already, but no luck.
Is there anyone on this forum who might help me bring this device back to the living?
I have all the schematics, including the one for a special PCB BC-ZS1, that is not mentionned in the original schematic, which I can post, including measurements and additional routing.
the sn# of this AL15A is 9, so I believe it's an early build one.
Any help would be highly appreciated!
Thanks, Ralph