Have you tested the diodes
You could upload some pictures, just in case what you think are diodes, may not be diodes. Depending on what diodes they are, modern 4148, 1n4001, 1n4004 can do the job of most oldies.The last 2 are most likely in a PS.
What about capacitors
Electrolytics can smell a bit cat pissy if they have problems.Are you able to measure the correct voltages now
There may be a faulty decoupling ceramic capacitor near to a logic chip,or an intermittent logic chip involved in the display control. I'm guessing you may be having a 'brown out' on power up if it's the power supply.
Power regulators don't usually have problems unless something somewhere else has made them work too hard.
Sometimes it's easier to measure power at the components themselves.If a schematic says 15 volts F.I, then you can expect to find a little bit more or less on testing. But I would suspect a problem if I found 13.5v instead F.I.
If you switch your Matrix on and the display is OK, does it go funny after a while
If you let it warm up and then do a power cycle, does the display then go funny
(try to answer these last two)
From:
wesleyknick <wesknick@...>
To:
oberheim@yahoogroups.com
Sent:
Sunday, 5 August 2012, 3:54
Subject:
[oberheim] Re: Oberheim Matrix 6, Dead
Assuming you were to replace the diodes on the power supply, is there a suitable substitute
I'm having some trouble identifying the 2 different diode types visually. 6 of the diodes on the power supply are marked with what appears to be a 'T85' followed in smaller font by a '5D' or '5C'. The two separate spherical diode types are marked with what appears to be a 'T3B5H'. A Google search of any combination of the markings brings up very little in the way of any reference to diodes. None of the manuals uploaded on various websites have any additional information and the only place the diodes are depicted is the block diagram. Anybody have a parts list out there they can upload
Most of the Korg and Roland service manuals have a parts list...
--- In
oberheim@yahoogroups.com
, jim finch <jahg88@...> wrote:
>
> You didn't mention how you were reading the powersupply voltages-but I didn't read the whole thread.If you use a O-scope you can see what is actually there,not just the D.C component. Most likely there is garbage riding on the +5V rail making the digital components see it as logic level shifts.
>