Ams dmx 15-80s eprom
- Thread starter GitouMan
- Start date
Help Support GroupDIY Audio Forum:
radardoug
Well-known member
It wont be the eproms. Its probably that the battery has corroded the processor board.
That was my hope, but after repairing the affected traces and doing continuity check, I didn’t progress any further… it passes audio and slightly effected but I have no display activity either. Hence I believe the eproms are a good point to work on (or rule out).
radardoug
Well-known member
Was the board corroded? If so its likely that the transistors that form the reset and battery control will be dead. I would change them.
To check, look at the reset line on the processor. It should go low and then high. Also check that clock is running.
here is a link to the processor pinout.
https://www.geeksforgeeks.org/pin-diagram-8085-microprocessor/
To check, look at the reset line on the processor. It should go low and then high. Also check that clock is running.
here is a link to the processor pinout.
https://www.geeksforgeeks.org/pin-diagram-8085-microprocessor/
amplexus
Well-known member
Ok so your EEPROMs are almost certainly fine. I'm not gonna say 100% but ime with these and the RMXs they are rarely the issue. If they ARE, there is a guy in the UK i think who burns them.
BUT Before you even go there, these things are finicky touchy princesses- there are about 100 other things that can cause them to go wonky or act up.
1) At bare minimum recap the power supply, make sure all rails are within a volt or so (less for the 5V), and make sure they're all clean. Ideally recap the whole unit, and replace any tantalum capacitors with a quality electrolytic.
2) Pull each card (carefully, and note the position, direction, and type) and clean the edge connectors with iso or iso and deoxit. Clean the fingers on all the card slots on the motherboard, make sure there's decent resistance when you push the card in.
3) At minimum, pull each ribbon cable noting where it connects and orientation and clean the pins and the sockets with deoxit. Inspect the cable for any fraying of the edges, and make sure the terminations are solid. I would strongly recommend also checking that there is NO continuity between any pins on a disconnected cable. Ideally, if you have the time and the skills, just replace all the ribbon cables now.
4) CAREFULLY and observing ESD precautions pull each socketed IC one at a time (this can be done while you've got the cards pulled in step 2). Clean the sockets with deoxit and isopropyl, and give the pins on each IC a very gentle cleaning with a fibreglass burnishing brush, or some 1000grit abrasive cloth. Rinse with isopropyl after. If any sockets give you very light resistance when you reinsert the IC, replace the socket.
5) Replace the battery. If any electrolyte has leaked inspect all traces it may have touched, clean well with isopropyl, and bridge any suspect traces as required.
6) Inspect for any fractured solder joints, or any broken component leads. Reflow ANY suspect joint.
IMO if you haven't done all of these things on an AMS unit before establishing if it works you're just making life harder for yourself. I've had bad sockets take down a whole unit, frayed ribbon cables (abraded by the sharp trimmed leads in those tight quarters) making intermittent shorts and glitching things out, no booting due to bad ribbons, glitchy audio because of bad pwoer rails.... in all of the AMS units I've serviced, doing the above 6 steps has brought almost all of them back to full, stable, working glory.
BUT Before you even go there, these things are finicky touchy princesses- there are about 100 other things that can cause them to go wonky or act up.
1) At bare minimum recap the power supply, make sure all rails are within a volt or so (less for the 5V), and make sure they're all clean. Ideally recap the whole unit, and replace any tantalum capacitors with a quality electrolytic.
2) Pull each card (carefully, and note the position, direction, and type) and clean the edge connectors with iso or iso and deoxit. Clean the fingers on all the card slots on the motherboard, make sure there's decent resistance when you push the card in.
3) At minimum, pull each ribbon cable noting where it connects and orientation and clean the pins and the sockets with deoxit. Inspect the cable for any fraying of the edges, and make sure the terminations are solid. I would strongly recommend also checking that there is NO continuity between any pins on a disconnected cable. Ideally, if you have the time and the skills, just replace all the ribbon cables now.
4) CAREFULLY and observing ESD precautions pull each socketed IC one at a time (this can be done while you've got the cards pulled in step 2). Clean the sockets with deoxit and isopropyl, and give the pins on each IC a very gentle cleaning with a fibreglass burnishing brush, or some 1000grit abrasive cloth. Rinse with isopropyl after. If any sockets give you very light resistance when you reinsert the IC, replace the socket.
5) Replace the battery. If any electrolyte has leaked inspect all traces it may have touched, clean well with isopropyl, and bridge any suspect traces as required.
6) Inspect for any fractured solder joints, or any broken component leads. Reflow ANY suspect joint.
IMO if you haven't done all of these things on an AMS unit before establishing if it works you're just making life harder for yourself. I've had bad sockets take down a whole unit, frayed ribbon cables (abraded by the sharp trimmed leads in those tight quarters) making intermittent shorts and glitching things out, no booting due to bad ribbons, glitchy audio because of bad pwoer rails.... in all of the AMS units I've serviced, doing the above 6 steps has brought almost all of them back to full, stable, working glory.
thank you for the advice. I will follow up dilligently and get back to here in the results!
