Doepfer

I've just re-organised my case and I somehow misconnected one module (missed the top 2 pins) in my monster case. The 2 A-118s were on the same power board as the misconnected module. The A-140 was not connected onto the bus, but I had put it into the case as part of my re-jig of modules.

Now, it appears none of them work as designed.

First A-118 module is board rev 1 from 1996 (one of my earliest purchases) with a TL064CN op-amp and a BC549 transistor. It powers up and one LED of random control lights up - nothing else functions...only output is a from the coloured noise socket - a regular 1ms square wave of approx 1.6-1.8V

Second A-118 module is board rev v3 2012 with an LF347N op-amp and BC547C transistor . This appears dead - no LED activity, no output

Third - A-140 ADSR Module is board rev 1 1996 (another early purchase!) TL084CN op-amp and HFC 4001BE FRAM , 4x BC549s and 1x BC559 transistors. Module sees incoming trigger pulse (via LED activity, H/L/M switch appears to work, but no output (checked via oscilloscope). Any reason this module's output would have ceased to function ?

I'm OK to DIY repair these if I know which parts could be affected - I'm assuming the IC's may be fried...???

Appreciate any help/advice

Thanks

Hello

Am 23.10.2016 um 08:38 schrieb sj230962@gmail.com [Doepfer_a100]:
> Question now moves onto why I have no -12V, but I do have +12V
Perhaps the cause is a broken pcb-trace. It might happen, when you 
remove and re-insert the flatconnector. The movement might break the 
solderjoint.

Do you have a multi meter with connectivity check? If yes, the test the 
connectivity between the pinheaders on the rihght with those on the left 
and with the flat connectorin the center.

Florian

Well what happened is you've shorted the negative rail to ground. Judging by your module dates I'm going to make the assumption you've got a doepfer linear PSU. It's more than likely you need a new LM337 regulator. You will also need a new piece of insulation to go between the regulator and heat sink. I built my own PSU without remembering to insulate the heat sink and the regulator blew immediately.

> On 23 Oct 2016, at 07:38, sj230962@gmail.com [Doepfer_a100] <Doepfer_a100@yahoogroups.com> wrote:
> 
> EDIT.....
> 
> 
> dismantled all of the modules from the monster base- issue is that there is no -12V getting to the 2 left hand side power boards...so its not a module problem (I should have checked the modules in a different case).
> 
> Question now moves onto why I have no -12V, but I do have +12V
>

Sorry didn't read properly. If you're getting it to one of your bus board fine then it's not going to be the regulator

> On 23 Oct 2016, at 12:20, florian anwander fanwander@mnet-online.de [Doepfer_a100] <Doepfer_a100@yahoogroups.com> wrote:
> 
> Hello
> 
> Am 23.10.2016 um 08:38 schrieb sj230962@gmail.com [Doepfer_a100]:
> > Question now moves onto why I have no -12V, but I do have +12V
> Perhaps the cause is a broken pcb-trace. It might happen, when you 
> remove and re-insert the flatconnector. The movement might break the 
> solderjoint.
> 
> Do you have a multi meter with connectivity check? If yes, the test the 
> connectivity between the pinheaders on the rihght with those on the left 
> and with the flat connectorin the center.
> 
> Florian
>