Vintage Synth Repair

I've also come across 2 or 3 SH-101's that had this same fault.
 
From memory, the SH-101's internal power regulating / DC-DC conversion is really weird, and poor contacts in the switch cause the 101's to drop it's tuning a bit.
 
On one of my 101's, even playing the keyboard near the power switch did cause the 101 to drop tuning by about a semitone.
I worked my power switch about 1000 times (with no power attached!) and this worked the switches contacts, and helped fix the problem heaps. ( $0.00 solution)
 
You could remove the switch a wash it out with alcohol.. but I never tried that.
 
Regards
Mike

--- On Thu, 4/12/08, Philip <eggwheatis@...> wrote:

From: Philip <eggwheatis@...>
Subject: Re: [vintagesynthrepair] New Memeber SH-101 (How to Hardwire Power Switch?)
To: vintagesynthrepair@yahoogroups.com
Received: Thursday, 4 December, 2008, 1:06 PM











In case my message didnt get through...
 
Like I said before I had 5 or so SH-101's most of them in mint, as new condition. They all did this. I couldn't find a fault. It never affected opreration so I put it down to a design anomaly.
 
Phil.
 


--- On Thu, 4/12/08, Roy J. Tellason <rtellason@verizon. net> wrote:

From: Roy J. Tellason <rtellason@verizon. net>
Subject: Re: [vintagesynthrepair ] New Memeber SH-101 (How to Hardwire Power Switch?)
To: vintagesynthrepair@ yahoogroups. com
Date: Thursday, 4 December, 2008, 1:53 AM




> Followed the tuning calibration document and still have tuning issues
> and have discovered it is the power switch... When wiggling the power
> switch it will change tune... I removed the switch and soaked it in
> electrical cleaner and resoldered it to find no change...

If you flex the switch and got that symptom and then changed it out and still 
get it, then the switch isn't the problem. I didn't think it would be, 
actually.

What's happening is that you're flexing the board, and that's affecing 
something else. From the stuff I snipped it sounds to me like that 
particular instrument was pretty sadly abused, so you may need to look 
further before you nail the problem.

A good strong light, maybe a magnifying glass or a pair of reading glasses, 
and some patience and you'll probably be able to track that down.

-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James 
M Dakin

 














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