Oberheim Matrix 1000 PSU

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Oberheim Matrix 1000 PSU

Postby Algorithm » Thu Apr 10, 2014 3:49 pm

My oberheim matrix 1000 will not turn on. I replaced the filter caps, saw that I still was not getting any voltage to 2 of the V-regulators. The only thing between the secondary side and the regulators is a diode bridge and then caps. I replaced the 4 diodes, STILLNOTHING. What am I missing here? Im getting a 0.12 at most on the regulator, sometimes as low as 0.7.
The other V regulators Ive replaced had the line coming in, just no output. These 2 are not getting anything from either way.. Could the regulator going wrong make this happen?

Here is a nice photo I found on google.


Image
Last edited by Algorithm on Sat Apr 12, 2014 7:47 am, edited 1 time in total.
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Re: Oberheim Matrix 1000 PSU

Postby atkbg » Thu Apr 10, 2014 8:55 pm

A few things first; You do (hopefully) have the PSU disconnected from the main board while doing this, right?
Don't plug it in until you have the correct voltages.

Schematic

What is the AC voltage selector set at?
Do you have a +5v? -5v? +12v? -12v?
Which regulators are you referring to?
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Re: Oberheim Matrix 1000 PSU

Postby Algorithm » Thu Apr 10, 2014 10:25 pm

Correct, the transformer is disconnected. I thought I fixed what was wrong, thats when I tested the regulator.
I think the region switcher is set to 120. kinda hard to get reference on where the setting is. I see there is a notch on the outer rim next to 120, but there is another notch on the rim at a different place.
I am missing the -12 and -5 If I remember correctly. Missing the 7905 and 7912, I get everything else.
I should also mention this must be an earlier revision, because it only has 1 7805. I have seen some pictures of black models with two 7805s, as well as the cream.


The transformer is putting this out
1=10.7
2=0.00
3=10.7
4=17.5
5=0.00
6=17.5
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Re: Oberheim Matrix 1000 PSU

Postby Algorithm » Sat Apr 12, 2014 12:14 am

Replaced the ceramic pairs on both regulators missing... Still no good. Anybody have any sort of idea? Anybody!
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Re: Oberheim Matrix 1000 PSU

Postby Algorithm » Sat Apr 12, 2014 7:46 am

Got the regulators back, but still no power to the front board. Rewired the main signals to that board, still nothing. I guess I will label this sorted even though its not. :D
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Re: Oberheim Matrix 1000 PSU

Postby atkbg » Sun Apr 13, 2014 2:14 am

Breathe. Its logic.

If you have power from the transformer windings, trace them until they stop. Going in with a shotgun only produces scatter results. But, you might hit the right spot.

Ceramics rarely fail.

Whats the serial number? Early? Late? Once we know, we can read the schematic and give you more.
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Re: Oberheim Matrix 1000 PSU

Postby Algorithm » Sun Apr 13, 2014 2:32 am

(laughs)

841529

pretty sure there is no difference besides the earliest units dont have the 2nd 7805. The spot is on the board, it is just bare, but when I say bare, I dont mean, removed, I mean, its fresh.

oh, the "units" "data dump" and "ext funct" led barely flashes when I switch it off. Its so dim I had to have it underneath something to notice.
It might only be the "units" led, because data dump and ext. funct are even dimmer...

It is on 120v definitely, I noticed the switcher access on the bottom...

To recap, I replaced the 3 caps leading to regulators, the 4 diodes bridge, the 2 ceramic pairs on both 7905 and 7912, and replaced the 2 10uf caps... then I noticed that there seems to be wax gluing the ribbons from the front display board. Upon further inspection it practically peeled off by glancing at it. It seemed someone tried gluing the broken wire, and didnt try to solder? Maybe it was broken but the glue held on? so I stripped the tips of those wires and reconnected them. That ribbon is the 6 wire. I then inspected the front board, there looked to be cold solder joints, so I touched those up. Still no dice.
thanks atk. & dont even worry about it if its a bother for you. I really dont mind.
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