Vintage Synth Repair

Measure your voltages at the power supply.  If correct, leave well enough
alone for now.  If not recap just that area, check, if still not good do the
regulators.  You can always measure right at the regulators but that wont
catch bad caps.

 

Some synths will fail in the first 48 hours if caps have dried out or failed
anywahere in the system (failing to ground) or there are poor/cold solder
joints or minor cracks at connectors or edge of failing components like
regulators or transistors.  I would leave it on for 12-24 hours at a stretch
for a few days.  I'd say 12 in case of fire while your asleep.  If it still
behaves well then be happy.  Over recapping can lead to other problems if
your not a pro at it.  You could crack solder joints at the connectors that
were sound before, etc. 

 

Lorne in Canada

From: vintagesynthrepair@yahoogroups.com
[mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of Rod Abernethy
Sent: Wednesday, May 29, 2013 6:38 AM
To: vintagesynthrepair@yahoogroups.com
Subject: Re: [vintagesynthrepair] Need some advice on fixing my OB-X

 

  

Well, the gods smiled down on me this morning.

 

I was looking through my Encore Midi Kit manual that I installed about 12
years ago and it dawned on me that I hadn't reloaded the original 32 patches
from the Encore card.  I reloaded the patches and it works!  I have the
simultaneous feeling of being a supreme idiot along with the joy of my OB-X
working again:)

 

Is there any upgrading I should do to my OB-X to help preserve the
electronics.for example re-capping, replacing pots, connectors, etc?

 

Thanks for all the help,

Rod

 

 

On May 29, 2013, at 9:19 AM, Rod Abernethy <rod@...> wrote:





  

Wes, I gave this a try but no cigar:(

 

Here's something that I've noticed with all the switches.   

 

All switches light on and off except:

 

Hold

Reset

Modulation/LFO/Rate/SINE

Modulation/LFO/Rate/S/H

Oscillators/Frequency 1/Waveform/SAW

Oscillators//Frequency 2/Waveform/SAW

Filter/Osc 2/Full

Filter/Noise/Half

 

All Programmer buttons turn on and off

 

Does anyone see a pattern in this?  Could it be a power supply problem  or
CPU problem?

 

Thanks!

Rod

 

 

 

On May 26, 2013, at 2:17 PM, 65 Lotus <Lotus@...> wrote:





  

 

Here's something I ran across from Wes Taggart of Analogics.  Worth a try...

 

=======================================================

 

Memory is a significant issue with the OB series of instruments (well any
instrument with memory) in that it will do some pretty crazy things if the
memory is bad or scrambled. Sometimes loading the memory is not enough. If
problems still persist after loading the memory and replacing the battery,
you may have to follow the procedure below:

Set unit to manual mode
pick patch A1
Turn every pot a couple times
Turn on and off every switch a couple of times.
This includes all the page 2 stuff also.
After the above, set a simple patch that you can easily identify. One
oscillator, wide open filter, gate like envelope.
After you have the patch, write it to memory location A1. 
Verify the patch is there by switching to another patch and then returning
to A1.
Once verified, write this patch to every memory location. A real pain for
those with 120 programs.
Load your program tape.

Scrambled memory creates issues because many times the value held in memory
is outside the memory address range. So where the expected value is 0-255
and the actual value is -1,304,495. CPUs do not do well with this type of
issue. Rotating the knobs allows the instrument to create a value within the
expected value.

Wes Taggart
Analogics