AMS service manuals RMX16 & DMX15

[pucho812]

Make sure the switches on the MCB card are set up correctly. What you are describing is the unit not switching in the memory cards correctly

will take a look at that... although I didn't flip any of the dip switches.  thanks

So far I have a ram3 in slot 12 and a ram4  in slot 16 PCB installed.
the rest of he cards seem to match but will go over it all again. 

 

[radardoug]

Memory cards should be in adjacent slots starting from 16. Theres your problem. And so it should be set up for 1 card for each channel, and the size switch set correctly

 

[pucho812]

Memory cards should be in adjacent slots starting from 16. Theres your problem. And so it should be set up for 1 card for each channel, and the size switch set correctly

o.k.  that is good to know. Now I need to sift through documents to find dip switch settings

 

[pucho812]

rather then go back and forth,

Here is the current layout inside the unit and dip switch settings.

 

[living sounds]

Talked with the repair shop today that had my 15-80s since early December. They rebuild the CPU board (battery damage) and replaced some questionable logic ICs. They had been stalling (I called every few weeks) and now they told me that they cannot get it to run reliably and won't attempt to repair it any more...

I had replaced all the ribbon cables, pots and all electrolytic tantalum caps 3 years ago, and it was running fine for ca. 2 years afterwards...

Since I will retrieve it and have to look at it myself again, any suggestions what to try would be greatly appreciated.

 

[radardoug]

Often once the micro has had the battery problem, the board gets very flaky. And some early AMS boards with black solder mask are very dodgy. When the battery cleanup is done it is mandatory to change all the transistors in the battery circuit. This affects reset operation.
You can buy new micro boards from David Kulka which are all cmos and better built! (I designed them).

 

[living sounds]

Thanks! I will have a look at the transistors on the card. I had replaced a couple (in the battery loading circuit) and I think they replaced more. If all of it doesn't help I will order that board from Studio Electronics. Not cheap (especially with the current shipping insanity, + taxes etc.), but I'm glad there are people making these availible. 

Might still be a problem on the mainboard...  :

 

[radardoug]

The other things that cause problems are the ribbons, but you have changed them I think? And also the motherboard sockets. If changing the transistors does nothing, try changing the motherboard socket.
The software that drives that board is partly on the micro, and partly on the effects extender card. So those ribbons are critical to keeping the micro happy.

 

[living sounds]

The other things that cause problems are the ribbons, but you have changed them I think? And also the motherboard sockets. If changing the transistors does nothing, try changing the motherboard socket.
The software that drives that board is partly on the micro, and partly on the effects extender card. So those ribbons are critical to keeping the micro happy.

Thanks! Yes, I remade all the ribbons. Do you happen to have a parts number / link for the motherboard sockets?

Obviously, the reason why a specialized repair shop would make sense (apart from their experience) is that they can simply exchange cards and find the error by elimination... But shipping this fragile unit around the world is also something I would like to avoid...

 

[radardoug]

I dont have a part number but I think David sells them. 22 pin double sided, .156 inch I think.
Yes, the best way to test AMSes is by board substitution. But its not uncommon to have multiple faults.
In your case, does the micro hang? So it boots up normally, and then the display will freeze or blank? Then it is either the micro card or the effects extender.

 

[living sounds]

I dont have a part number but I think David sells them. 22 pin double sided, .156 inch I think.
Yes, the best way to test AMSes is by board substitution. But its not uncommon to have multiple faults.
In your case, does the micro hang? So it boots up normally, and then the display will freeze or blank? Then it is either the micro card or the effects extender.

From what they have told me, it crashes unpredictably. Will fetch it next week and report back. Thanks!

 

[radardoug]

Do you have the ability to program eproms? If so, PM me.

 

[living sounds]

Retrieved my dmx 15-80S today. Even with the eproms provided by Doug (thanks again!) they couldn't repair it. It shows essentially the same erratic behaviour. I think it may be multiple problems.

The only think noticeable that I think I didn't detect before is a litte high-pitched noise emitted from the switchting PSU. They say they checked the power and it was all right, of course.

When I get it to turn on and allow programming via the front panel (takes a few resets often) I for some reason cannot set the harmonizer to 1. Hitting the 1 triggers erratic behaviour again.

Any more hints on what to do? Thanks!

 

[radardoug]

That indicates problems with the micro and/or effects extender. The software I supplied should allow you to determine if the effects extender is the problem.
Disconnect the ribbon cables to the effects extender and confirm that all tests work as they should. Then reconnect the effects extender one cable at a time and check again.