MXR 185 Drum Computer

[bradholland]

So I picked up one of these thats in a bit of a mess, Kinda working, kinda not. She's quite a beautiful beast, much resembling a Linn or DMX.
Some pads play a drum fine, other play two drums at once or trigger the wrong sample, others not at all or outputting sound that is everything but a drum. lol

I'm thinking I should start by looking at the latch switch logic ic's (74ls series) right after the pads... I managed to get some schematics.

Wondering if anyone has experience with these babies and could offer me some guidance with the unit?
peace,

 

[bradholland]

an update: I found that for the first 20seconds or so of the machine being turned on, the sounds that work will play on their own, then after this they start getting joined together.
for instance: If i tap the snare button I get just snare for 20 seconds and then after that hitting snare plays the snare and tom together...

component freezer spray didnt turn anything up yet..
I've started replacing some of the 4000 series IC's and replacing the with sockets as I go....

I can upload schematics to teh board if it will help anyone? anyone else have one of these machines?

 

[erikb1971]

I am sorry that I will hardly be of any real use. That is one cool drum machine though!I read somewhere it was used on a forest b the Cure... how cool is that!
I used to have an old akai drum-computer that eventually got completely screwed up. Until I found that you could some how give it a hardware reset. Did that and.. good as new!
would that be an option to figure out for yours?

Good luck!
 

 

[12afael]

I think first of all you must replace all electrolitic caps if this is an old unit the power supply can make a lot of problem. then you can check other modules .

 

[bradholland]

Yeah I changed all teh caps first thing.
I got it working in the end.
For every IC I took out I replaced it with a socket for good measure.
After pulling out all the CD4011's (quad nand gate ic's) and then replacing them in the new sockets, obvioulsy not in the same order as they came out, pads that were not working suddenly worked and other that previously were working then did not.
Swapping the 4011's around confirmed this and so I now know I just need to replace 4 broken 4011 IC's
Very pleased with myself!

and yeah, this thing is uber cool, It's pretty much an LM-1 from what I can make out.

 

[analogguru]

I can upload schematics to teh board if it will help anyone?

What are you waiting for ? This here is the right place:
http://groupdiy.com/index.php?board=19.0

(and by uploading your chance for possible help will increase too....)

 

[ArtichokeMan]

Hi guys, I'm a new user of this great forum i hope you can help me. Found one of this beauties and get it. I love all the '80s drum machine, i'm not a collector just an user.
Case in very bad condition, all seems working fine except one of the most important things: the RUN STOP button. When I push it the drum machine freeze, do you know a solution? Can you help me? :'(
I can also ear a little buzz when is on...

Anyway I love it

Thanks and sorry for my english

 

[Nickmontoya]

What are you waiting for ? This here is the right place:
http://groupdiy.com/index.php?board=19.0

(and by uploading your chance for possible help will increase too....)

I need a copy of the schematic! Can you please post it, that would be great!

 

[aliendelon]

i would also ask for a schematics please!

 

[mjrippe]

I have never seen them online.  I had a broken machine and poor quality photocopy schematics about 25 years ago but I sold all of it together.  Good luck 

 

[oddfreqsynth]

What are you waiting for ? This here is the right place:
http://groupdiy.com/index.php?board=19.0
(and by uploading your chance for possible help will increase too....)

I have added the schematics (not the best quality) and owners manual:
https://groupdiy.com/threads/mxr.84912/

 

[grahamteeling]

Yeah I changed all teh caps first thing.
I got it working in the end.
For every IC I took out I replaced it with a socket for good measure.
After pulling out all the CD4011's (quad nand gate ic's) and then replacing them in the new sockets, obvioulsy not in the same order as they came out, pads that were not working suddenly worked and other that previously were working then did not.
Swapping the 4011's around confirmed this and so I now know I just need to replace 4 broken 4011 IC's
Very pleased with myself!

and yeah, this thing is uber cool, It's pretty much an LM-1 from what I can make out.

Hi Brad! Sounds like you nailed this. I have one here that needed faders replaced and a midi kit installed. all that is done now ... She has a super low volume and also seems to be doing some random things. when I'm in pattern write mode she sometimes powers off... scratching my head a little. Any advice? thanks G