Product Description
Finding a vintage digital AMS rack unit in top operating condition is becoming ever-harder; 'cheap' examples can be found online, but they can require a great deal of tech time, and sometimes fixes are simply not possible. Manufactured from 1979-1985 these were the cutting edge of digital technology; AMS designed and built these with great care and attention to detail and they soon became ubiquitous in studios worldwide. The DMX can be heard on thousands of recordings from the 80s to the present day and was certainly one of the core studio staples that defined the musical soundscape of the 80s. Today AMS units such as this can still be found in regular use in top studios worldwide. Their sound is still so coveted that Universal Audio have now collaborated with AMS to produce the UAD plug-in version. However, as with all digital emulations of vintage hardward, nothing can match the sound of the real thing.
The operation manual can be found here. Handy recall sheet here.
Currently set to 240v operation.
Serial Number: 3003
Tech Report: Soundgas DMX 15-80s #3003
Missing bottom panel, missing nudge button caps, missing internal IEC safety cover.
Wrong on/off switch fitted. Replaced with correct factory switch and cap nut.
CHB regen pot loose. Retightened.
Unit has been recapped recently. Some caps are too tall so shorting against other boards. Replaced.
No power: Main fuse missing…replaced.
Fan wires cut and not connected to power.
Transformer wires cut at IEC voltage selector terminals. Seems to have been hardwired for 240v only, but mains voltage wires just taped together!
Bad connection within IEC voltage selector input. Repaired and wired back to factory.
Remove all cards test PSU, all voltages present.
Replace cards.
+5vdc fuse blowing under load. Replaced wrong +5vdc Schottky Rectifier on motherboard. Replaced wrong caps, rewound wrong value inductor on switch mode supply. Wired large +5 reservoir cap correctly.
Remove all cards, test PSU.
Replace cards.
Power present +15,-15 and +5vdc. OK.
No audio. Bad tracks, rear of Deglitch card DIL socket.
Nudge up button not working. Repaired racked solder joint on back of IC on front panel board.
Assembled and fitted new ribbon cable set.
Fit new fan.
Cleaned all edge connectors and sockets.
Cleaned out internals of dust with compressed air.
Now working and reliable. Check voltages (OK)
8hr burn test. Test battery charging and NVRAM data retention: Passed.
Please Note: It is very important all vintage AMS RMX & DMX series rackmounts are powered for at least an hour at least every 6 months or risk of NVRAM battery leakage is greatly increased. It is highly recommended the battery is replaced every 5 years as routine maintenance on these units to avoid severe damage to the processor card.
The operation manual can be found here. Handy recall sheet here.
Currently set to 240v operation.
Serial Number: 3003
Tech Report: Soundgas DMX 15-80s #3003
Missing bottom panel, missing nudge button caps, missing internal IEC safety cover.
Wrong on/off switch fitted. Replaced with correct factory switch and cap nut.
CHB regen pot loose. Retightened.
Unit has been recapped recently. Some caps are too tall so shorting against other boards. Replaced.
No power: Main fuse missing…replaced.
Fan wires cut and not connected to power.
Transformer wires cut at IEC voltage selector terminals. Seems to have been hardwired for 240v only, but mains voltage wires just taped together!
Bad connection within IEC voltage selector input. Repaired and wired back to factory.
Remove all cards test PSU, all voltages present.
Replace cards.
+5vdc fuse blowing under load. Replaced wrong +5vdc Schottky Rectifier on motherboard. Replaced wrong caps, rewound wrong value inductor on switch mode supply. Wired large +5 reservoir cap correctly.
Remove all cards, test PSU.
Replace cards.
Power present +15,-15 and +5vdc. OK.
No audio. Bad tracks, rear of Deglitch card DIL socket.
Nudge up button not working. Repaired racked solder joint on back of IC on front panel board.
Assembled and fitted new ribbon cable set.
Fit new fan.
Cleaned all edge connectors and sockets.
Cleaned out internals of dust with compressed air.
Now working and reliable. Check voltages (OK)
8hr burn test. Test battery charging and NVRAM data retention: Passed.
Please Note: It is very important all vintage AMS RMX & DMX series rackmounts are powered for at least an hour at least every 6 months or risk of NVRAM battery leakage is greatly increased. It is highly recommended the battery is replaced every 5 years as routine maintenance on these units to avoid severe damage to the processor card.