Vintage Synth Repair

The preset keys can have the same problem as any of the keys...that is 
that dirty contacts will prevent them from operating. I had the same 
symptoms on my H when I first got it, and still do from time to time on 
those keys that see little usage. Normal operation on mine returns when 
I hold the Cancel key down and tap the offending key rapidly 20 or so 
times to clean the contacts. Maybe you will get lucky and this will 
help...at least it is worth a try.
As far as the key not staying down, this is not too hard to 
fix...however getting to the mechanism can be a challenge, especially 
on the lower manual.
The mechanism is simple; there is a spring loaded bar that swings on an 
arc under the preset keys. When a key is pressed, a flexible "finger" 
under the key holds on to that rod. The Cancel key pushes that rod away 
from the finger, and releases the preset key.
When the preset key no longer stays down, the "finger" is probably worn 
or stuck with dried grease, and can be cleaned and/or bent slightly to 
restore it, assuming the finger is not broken.
I can send pictures of the mechanism if you would like.
In order to reach the mechanism, the keys obviously need to be removed.
If you have never done this, please let me know and I can walk you 
through it. Also, if you find broken parts during the process, please 
let me know as I  have a couple H's in pieces out in the shop and would 
be glad to donate what I can.
Bob


--- In vintagesynthrepair@yahoogroups.com, "fsimon100" <fsimon001@...> 
wrote:
>
> H-100
> My preset keys won't stay engauged. How do you disassemble to get 
> underneath keys to fix. Also I have low volume if I hold them down 
> manually. 
> I know final tube outputs are good but not sure where the low signal 
> is. Do I scope out from the tonewheel somewhere then at a pre-amp. 
Like 
> I said I injected a tone into the final tube amps and have strong 
final 
> stage.
>