AMS RMX16 question

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

jensenmann

Well-known member
Joined
Oct 10, 2004
Messages
2,850
Location
Karlsruhe, Germany
I´ve been offered a RMX16 Reverb for a pretty good price but it seems to have some problems with the display. A few LEDs don´t work for whatever reason. Is anybody here who teched one of them and could tell me if it´s a big effort to repair this? Are the parts (7segment/driver ICs) still available? Are the parts accessable or are they potted?
Rumour says that the RMX16 is hard to repair so I´m asking in advance before I throw out bucks for having a nonrepairable piece of crap which gives me more grey hair than I already have.

thanks :thumb:
 
Can´t help you but I have a RMX16 with the same problem. I use it anyway and it sounds fantastic but I would also like to know if it´s fixable.
 
It's been perhaps 10 or 15 years since I worked on these, but I remember that they are a very delicate (hmmm, maybe just bad) construction. Loads of flatwires which run over sharp edges, getting cut in and creating all kids of intermediate connections, a fan pulling dust, a battery that gets overcharged is what I recall immediately. Fixing that made them pretty reliable. I have no idea for the LEDs, buffers should most likely not be a problem and all parts are accessible - if I remember right. I don't remember anything potted.

Michael
 
I spend a lot of time working withe these folks: http://studioelectronics.biz here in the Los Angeles area. They have searched the world for documentation, spare parts, and info on RMX & DMX units, and have become pretty expert in their repair.

The problems you are describing can very often be fixed by replacing the ribbon cables. That's part of Studio Electronics' basic DMX/RMX restoration process.

They've repaired over 100 units in the last 1.5 years, so that's a pretty good track record.

For more info, email [email protected].
 
I've got a schematic of the front panel. It looks like the 7-segment displays are multiplexed with an RCA CA3082 transistor array handling the data lines, and 75492 MOS to LED Driver ICs handling the chip selection. Chip selection is decoded by 74LS273 chips. There are a couple of 7406 ICs sprinkled in as well. 7-segment displays are TIL313's and TIL327's. The alhpa-numeric displays are TL1414 4-character "Smart" displays. I googled the 7 segment displays and got back mostly links to the giant surplus and obsolete chip vendor sites, so they may be tricky to source.

There are no potted parts inside.

As mentioned, Studio Electronics has a good reputation for AMS repairs, but I would discuss it with them before buying the unit, to avoid any repair cost sticker shock.
 
David Kulka, is a vary nice fellow. He fixed my AMS delay, but it was a nasty audio problem. Give a call he may tell you the LED replacement or send you some. He can also be found on ebay advertising his repair services.


I replaced some segment LEDs in a Klark teknik and it was a PITA. Sourcing was also fun, but it looks like you have more going on than a bum LED segment.
 
There is also the chap in the UK who was *the* service engineer for AMS. His name is Howard Jones. Unfortunately I don't have his details here at home, but I will post them on Monday when I get to work. He now has his own company still repairing AMS's.
 
Hi folks and thanks for the kind words. This is my first post on this forum. Actually there were other topics that I wanted to comment on, but I had trouble registering. Anyway, hello.

Jensenmann, as Steve Anderson mentioned, check the ribbon cables first, specifically the two short ones that go from the microprocessor board (the board on the right, near the transformer) to the front panel. You might try flexing and moving these slightly while the unit is running. If anything changes on the display while doing this, you have a bad cable.

Also, you could probably "borrow" the long cable that goes to the remote connector, and use it to replace the front panel ribbons, one at a time, to see if the problem clears. If you do this, make notes or take pictures before you unplug anything, and be very careful not to plug anything in backwards.

It's possible to have a problem in the IC's on the front panel, but this is rare. We have never seen a 7-segment display fail on any AMS; it's extremely unlikely that this is the problem. The microprocessor board would be more of a suspect than anything on the front panel. But again, the ribbons are the first thing to check. If they are really dusty and crusty looking, that tells you something. Even if they look ok, it's not a bad idea to just replace them both with new cables, and see what happens.
 
[quote author="guavatone"]I heard Howard Jones cut himself off from this line of work. or maaybe he's just retired[/quote]
The last time I spoke to him he was still in business. That was over a year ago, but he was still working on them then.
 
Thanks for dropping by David, and sharing some quality troubleshooting advice. (BTW I am the guy who's AMS you serviced through Paul Fox, and later sold you the Broadcast DMX)
 
Update...

Just tried getting hold of Howard Jones. His website no longer exists, and the phone number I had for him is saying "This number does not take incoming calls".
So it looks like you are right Charlie, which is a great shame and a great loss.
 

Latest posts

Back
Top