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Other ADA Gear => Step On It! => Topic started by: aoresteen on September 06, 2015, 04:39:25 AM

Title: Broken MC-1 - Where to send for Repair?
Post by: aoresteen on September 06, 2015, 04:39:25 AM: I have two ADA MC-1 foot controllers. One is dead, it does not power up. The other one works perfectly.

Where should I send the broken MC-1 to for repair?

Thanks!
Title: Re: Broken MC-1 - Where to send for Repair?
Post by: rnolan on September 07, 2015, 01:57:26 AM: You may be able to fix it yourself. How are you with electronics ? I don't think the MC-1 is particularly complicated and MJMP or others may be able to step you through the fix. It's certainly worth opening it up and check for anything obvious.
So your in Newnan GA USA, not sure where that is or who's the closest decent tech. Others here should have some recommendations.

@ MJMP, do you have a schematic for the MC1 ?
Title: Re: Broken MC-1 - Where to send for Repair?
Post by: MarshallJMP on September 07, 2015, 09:28:49 AM: Nope no schematics for the MC-1.

The MC-1 isn't that easy to fix,you need a scoope or a logic probe to check it out.You can try to measure the 5V and after that it's ll digital.
Title: Re: Broken MC-1 - Where to send for Repair?
Post by: rnolan on September 07, 2015, 11:37:54 PM: IIRC It's based on a Zialog Z80 CPU. We had to write a Z80 emulation program in Pascal when I was at uni, interesting assignment.
Title: Re: Broken MC-1 - Where to send for Repair?
Post by: aoresteen on September 08, 2015, 07:06:17 AM: Thanks all!

I'm ok with electronics. Issue is my bench is not set up. I do have a scope & probes. I'll look at the 9v/5v power feed and see if that brings it back to life.

I was hopping that there is someone out there that knows the MC-1 and can fix it faster than I can.
Title: Re: Broken MC-1 - Where to send for Repair?
Post by: MarshallJMP on September 08, 2015, 02:28:11 PM: Well i could fix it for you but then you'll have to ship it to belgium.Since you have the equipment that would be a bit stupid.Let's try to fix trough this topic or email.So first check the 5V,starting from the dc adaptor input trough a diode (1N400x),then a cap into a 7805 regulator.If you have 5V at the output of the 7805 then the next thing to check is if you have a clock signal on pin 6 of the Z80 µcontroller.I need to check it out but i think it works on 2MHz.I have the pcb of MC-1 here and it seems it has a 4MHz crystal (buffered by a 74HC04 (hex inverter) pin 1 and 2) going to pin 3 of a 74LS74 (D flip flop),there it will be devided by 2 so you will have 2MHz on pin 5 of the 74LS74 then it goes to pin 3 of the 74HC04 and pin 4 goes to pin 6 of the Z80.Also make sure sure pin 26 (reset) is high (5V).
I hope this makes sence,if not let me know.BTW the 74hc04 is on the right side of the crystal,the LS74 on the left side.
Title: Re: Broken MC-1 - Where to send for Repair?
Post by: Dante on September 10, 2015, 04:12:45 PM: MJMP to the rescue!!! (again)
Title: Re: Broken MC-1 - Where to send for Repair?
Post by: rnolan on September 11, 2015, 12:02:45 AM: Quote from: Dante on September 10, 2015, 04:12:45 PM
MJMP to the rescue!!! (again)
+1 :thumb-up: :bow:
Title: Re: Broken MC-1 - Where to send for Repair?
Post by: MarshallJMP on September 11, 2015, 03:58:33 AM: ::)
Title: Re: Broken MC-1 - Where to send for Repair?
Post by: chrismilne on January 30, 2018, 08:54:38 PM: Did you have any luck? I just tried to fire mine up after many, many years and no power...
Title: Re: Broken MC-1 - Where to send for Repair?
Post by: MarshallJMP on January 31, 2018, 12:27:49 PM: Maybe a stupid question, but are you sure you're using a adaptor with the correct polarity?
Title: Re: Broken MC-1 - Where to send for Repair?
Post by: chrismilne on January 31, 2018, 05:41:52 PM: Yeah, i still have the original ADA adapter. Though i guess it could be bad...
Title: Re: Broken MC-1 - Where to send for Repair?
Post by: MarshallJMP on January 31, 2018, 09:26:37 PM: Well that's easy checked with a multimeter.