EMS Synthi A Mk1 question

[Tony K]

> From:          jun at h-und-p.de

On  Tue, 21 Oct 97,  Joerg wrote

> Hi list,
> 
> 
> a while ago I acquired a Synthi A Mk1 in relatively good condition. Although everything
> works at the moment, I asked myself what I will do, if one of the ICs (PA234) used for
> the output amplifiers and for the reverb fails. They are no longer available and 
> I must admit, altough the Hinton pages are very valuable his comment 'if one of this
> ICs fails then its time to rebuild the board' aren't especially helpful for me as
> I am not an EE. So, could someone give me a hint? Has someone already had this problem
> and how did he/she solve this? Any help greatly appreciated!
> 
> Regards
> 
> Joerg
> 
>

I understand your concern because these are tough to replace hence 
the mkII board eliminating them completely for  a discrete design  
of 741 and AC176K ,AC153K npn-pnp pair.The reverb drive was replaced 
by an even more obscure MFC6070 1Watt device (Vcc max=20 v).

I've got a few for repair purposes only ,but am planning to do a 
subboard to take care of this problem.

I wouldn't worry too much about it as long as you don't crank things 
way up (don't do a gig with internal speakers !).I've had no problems 
with my mkI and neither has my friends.

Also it wouldn't be impossible to redo a mkII pcb (new design of 
course) and maybe that's the best choice ultimately.

Any comments welcome.

Tony K
IC1 Electronics