AMS RMX-16 any good? Easily repairable?

Heya,

A friend of mine is clearing out his studio and one of the things he's sell is an AMS RMX-16 with a broken power supply for $180. For that price it seems worth it, but I don't want to buy it and then find that it's impossible to repair. Do any of you guys have experience repairing this thing? Do you think it's worth it?

The other question I have, of course, is: is it any good? Still usable these days?

Good? Yes. Very.

Easily repairable? Definitely not.

But at that price, it's a must-buy..!

Jakob E.

I want it if you don't.
Peter

the guy in LA that knows these gave it up a few years ago. you could send it to england for a flat fee which was very high. broken power supply or wont boot? I have repaired a few and most of the intermittant probs were card seating but you had better not break one ot the dozens of hook-up wire mods on every card. they have descreet computers on them that need magic fairy dust to operate. beautiful sounding peice though. be ready for trouble. keep cool and dust free.

That thing sucks, send it to me and I'll take care of it for you. :twisted:

Seriously though, it is a very difficult piece to work on. The primary suspects in both the RMX and DMX are the ribbon cables between the cards. Those almost always need to be replaced. The other problem is the fact that the primary bits are mostly obsolete at this point, and so are very difficult to find(and expensive when you do). I don't seem to remember the power supply being particularly odd, so you may be in luck with that. $180 is well worth it, as even if you decide not to keep it you could probably get more for it on ebay even in non-functional shape. AMS is also notoriously difficult about releasing any kind of service information. The only guy left that I know of who still works on the AMS stuff is Howard Jones at Kaya Music Systems in Burnley. I believe the email is [email protected] , he's quite helpful with questions and parts for these units (as well as servicing them!).

Good luck,

Zach

I can fax you the power supply sheets from my service manual if you need them, the toroidal transformer has been known to fail, and it has an odd winding to run the fan at whatever mains voltage you switch the unit to, but that is easily got around. The supply is pretty conventional apart from that.

Otherwise, as everyone has said, they are challenging to repair. Many of the faults that people ascribe to bad sockets are sometimes not that at all - the solder that AMS used on it's PCB's wasn't too good, and the PCB tracks are prone to hairline cracks, so often when people reseat the boards, they are actually flexing the PCB enough to get the track/solder joint to make contact again.

At that price, buy it without question.

I've run into the "reseat it and it shall work" bit with AMS as well. Thanks Steve, for letting me know why. I should have guessed. They are a nice sounding unit. The classic nonlinear (reverse) as I remember.

The classic nonlinear (reverse) as I remember.

Click to expand...

The coolest!

:thumb: :thumb:

My unit had a maddening problem where it would lose clock intermittently. I re-soldered the crystal as clock has an uncanny ability to mess with solder joints, and still no luck. As soon as I then de-soldered and completely removed the crystal, cleaned the old solder away, and re-soldered the crystal with all fresh solder the machine came up perfect, all trace of the problem gone.

I then removed most of the chips on the CPU board and installed gold plated machined pin IC sockets, and did the same for all the EPROM sockets, and during this process I found just how fragile the tracks can be, and how they seem to get corrosion near the solder joints and barely make contact. The solder seems to be a poor alloy combination too, I used a Denon desoldering pump and some braid as a backup, so I was not putting any undue stress on the tracks.

As others have mentioned, it is a good idea to replace the headers, header sockets and ribbon cables, and as Rob Squire has mentioned, if the battery has leaked at some time in the past on the CPU board, the corrosion can track up the nearby transistor legs and fox them, so out they go.

Quite a few tantalum capacitors in there, swap em all out, they are a timebomb just waiting to go low resistance, and as Jakob has suggested in another post, swap out the PSU filter electro's too. The fan might be more effective blowing in rather than out if it is filtered too.

That's the one! it sat in the reverb graveyard on the top shelf of my shop for a couple of years, it had been worked on by several techs who said it was unrepairable so the owner gave it to me. I left it there and didn't really give it much thought, and one day when things were quiet and I was tired of working on synthesisers I thought I would take a look at it for shits and giggles since I have the service manual. Well, it took me 5 days to fix all the faults, but it was worth it, it is so lush and thick. (kind of boingy too, but that is because of the way the feedback algorithm works I guess). Instant Trevor Horn! (Well, perhaps if I could find a Publison Infernal Machine to go with it). :shock: :razz:

I guess the other technicians just weren't hungry enough.

Here it is in the studio, and what's that above it? Could it be an unmarked GSSL? :razz: I wish I could find some of the SIFAM meters you can see at the bottom of the photo on the ADR unit - they rest to the RIGHT normally, and deflect left.

[/img]

[quote author="Nat"]Heya,

A friend of mine is clearing out his studio and one of the things he's sell is an AMS RMX-16 with a broken power supply for $180. For that price it seems worth it, but I don't want to buy it and then find that it's impossible to repair. Do any of you guys have experience repairing this thing? Do you think it's worth it?[/quote]

By the bye, there were 2 different supplies AMS used, a linear and a swichmode depending on how old the unit is.

[quote author="Steve Jones"]there were 2 different supplies AMS used, a linear and a swichmode depending on how old the unit is.[/quote]
Yep... and two different case construction variations as well.

Keith

[quote author="SSLtech"][quote author="Steve Jones"]there were 2 different supplies AMS used, a linear and a swichmode depending on how old the unit is.[/quote]
Yep... and two different case construction variations as well.

Keith[/quote]

That's right! I had forgotten about that, the later cases were much nicer than the early ones with the black box bolted onto the back of them.

Damn and blast. Apparently someone else bought it before he caught my email!

Damn!

And once again, for good measure. Damn!! :roll: