ADA Depot - A Forum To Support Users of ADA Amplification Gear

Let's Get Technical => Troubleshooting Problems => Topic started by: willem on November 25, 2014, 09:33:44 AM

Title: MP-1 diagnosis
Post by: willem on November 25, 2014, 09:33:44 AM

Hi all -

I have an MP-1 that I last turned on about 15 years ago (it has been in a rack in the closet since then). When I powered it on today, the display was dark (it did flash briefly on startup - see image attached). That doesn't look like an error code, but I mention it because it means that the display itself is still functional.

The fuse is good. The power supply has a slight hum. Both tubes glow. But no display and it's non-responsive when I press 'Edit'. The unit has the 2.0 EPROM and no mods. It appears to have the original tubes.

I don't have a meter or much electronics experience, so I'm unable to do much diagnosis, but if anyone has suggestions, I'd appreciate hearing them. I can shoot an internal photo if that would help.

Thanks,
Willem

Title: Re: MP-1 diagnosis
Post by: RobbHell on November 25, 2014, 10:28:25 AM

Check your PM

Title: Re: MP-1 diagnosis
Post by: MarshallJMP on November 25, 2014, 12:53:22 PM

Remove the tubes and try if it wants to start.Removing the tubes gives the mp-1 more power to start.
Could also be the reset circuit or a bad connection in the grey ribbon cable going from the mainboard to the midi board.

Title: Re: MP-1 diagnosis
Post by: willem on December 01, 2014, 06:15:15 PM

Thanks for the replies, guys.

I removed the tubes and powered it up. It took a couple of minutes, and then the display had an 'e.' value and all the odd numbered LEDs were illuminated (1,3,5, etc. plus Edit)

After a couple of minutes, the display and all the LEDs flashed randomly for about two minutes (the Clip LEDs did not). Then all the lights went out. The transformer had a regular (and normal) hum throughout.

I waited about 5 minutes but there was no more activity. I powered the unit down, waited a minute, and restarted it. This time there was no activity at all, so I shut it down after about 5 min.

The ribbon cable looks ok - there are no cuts and the socket is seated squarely on the board. The EPROM is secure as well. Is there anything else I can check/reset, or do I need to find someone with a meter?

Thanks,
Willem

Title: Re: MP-1 diagnosis
Post by: MarshallJMP on December 02, 2014, 10:55:53 AM

Could be the reset circuit.See pdf file.(#1,2).Also remove the grey ribbon cable on the main board and put it back in,just to rule out a bad connection there.Make sure you insert it back the correct way.