Doepfer

Having recently acquired a damaged A-136, I have now ended up with a damaged A-143-1. At least the Waveshaper was sold as damaged, the A-143-1 was sold as new :(

Channel's 1, 2 and 3 seem fine. Neither of the two LED's on channel 4 light up and the output's seem to do nothing. I noticed on the back of the module channel 4 is the first channel to receive power from the bus. I guess this could be a case of the module's power having been plugged in upside down. The waveshaper had the same problem and replacing the two amp's fixed it. There was visible burn markings on the solder of the waveshaper, channel 4 on the A-143-1 looks fine, I can't viably see anything wrong with it, channel 4 looks identical to 1, 2 and 3. I guess replacing the four chips (Amps?) on the PCB would be the first thing to try? 

Thanks for any help,
Jonathan

"on channel 4 light up and the output's seem to do nothing" I guess that's not quite true:

http://soundcloud.com/user8805415/a-143-1-test

In the above test: A-110 Saw -> VCA -> Record. A-143-1 ENV out (all four in turn) -> A-110 CV1 input.

Jonathan


--- In Doepfer_a100@yahoogroups.com, "jonathan.heslop" <jonathan.heslop@...> wrote:

>
> Having recently acquired a damaged A-136, I have now ended up with a damaged A-143-1. At least the Waveshaper was sold as damaged, the A-143-1 was sold as new :(
> 
> Channel's 1, 2 and 3 seem fine. Neither of the two LED's on channel 4 light up and the output's seem to do nothing. I noticed on the back of the module channel 4 is the first channel to receive power from the bus. I guess this could be a case of the module's power having been plugged in upside down. The waveshaper had the same problem and replacing the two amp's fixed it. There was visible burn markings on the solder of the waveshaper, channel 4 on the A-143-1 looks fine, I can't viably see anything wrong with it, channel 4 looks identical to 1, 2 and 3. I guess replacing the four chips (Amps?) on the PCB would be the first thing to try? 
> 
> Thanks for any help,
> Jonathan
>

Jonathan,

I don't have access to any of the modules you're referring too,
but in general -- assuming they've been powered backwards,
the first things to go are the electrolytic (or tantalum) caps
near the power connector. Burn markings are most likely
coming from those caps which "crossed over to the dark side".

Replace these first, then work your way down to any other
possible tantalum caps, the IC's, then the transistors...
though there is no definite way of components knowing
which components die first.
YMMV.

_g

On 31 Oct 2010, at 17:16, jonathan.heslop wrote:

> Having recently acquired a damaged A-136, I have now ended up with a damaged A-143-1. At least the Waveshaper was sold as damaged, the A-143-1 was sold as new :(
> 
> Channel's 1, 2 and 3 seem fine. Neither of the two LED's on channel 4 light up and the output's seem to do nothing. I noticed on the back of the module channel 4 is the first channel to receive power from the bus. I guess this could be a case of the module's power having been plugged in upside down. The waveshaper had the same problem and replacing the two amp's fixed it. There was visible burn markings on the solder of the waveshaper, channel 4 on the A-143-1 looks fine, I can't viably see anything wrong with it, channel 4 looks identical to 1, 2 and 3. I guess replacing the four chips (Amps?) on the PCB would be the first thing to try? 
> 
> Thanks for any help,
> Jonathan
>

Hello

if the chips are socketed, try swapping the chips of pcb 4 with other 
pcbs. I suspect 555 to be dead. TL082 usually survive wrong powersupply 
at 12V.

Florian

Hi Guy

> the first things to go are the electrolytic (or tantalum) caps
> near the power connector.
Doepfer uses 25V caps ... it doubt they would be destroyed by wrong 
polarization.

Florian

Now why didn't I think of that :) I tried swapping all 4 chips from channel 3, No joy though.

I'm guessing channel 3 and 4 chips are identical?!?

Jonathan

--- In Doepfer_a100@yahoogroups.com, Florian Anwander <fanwander@...> wrote:

>
> Hello
> 
> if the chips are socketed, try swapping the chips of pcb 4 with other 
> pcbs. I suspect 555 to be dead. TL082 usually survive wrong powersupply 
> at 12V.
> 
> Florian
>

On 10/31/10 2:32 PM, Florian Anwander wrote:
>
> Hi Guy
>
> > the first things to go are the electrolytic (or tantalum) caps
> > near the power connector.
> Doepfer uses 25V caps ... it doubt they would be destroyed by wrong
>

I second other recommendations to swap those IC, esp. if socketed, it is 
really easy and fast. 25V cap would not likely be destroyed by reverse 
power.

Tony


[Non-text portions of this message have been removed]

On 31 Oct 2010, at 22:11, Tony Rolando wrote:

> 
> On 10/31/10 2:32 PM, Florian Anwander wrote:
> >
> > Hi Guy
> >
> > > the first things to go are the electrolytic (or tantalum) caps
> > > near the power connector.
> > Doepfer uses 25V caps ... it doubt they would be destroyed by wrong
> >
> 

I agree that electrolytes don't blow as fast as tantalums.
The latter ones I've seen blowing skyhigh with reversed power.
Still, if there's burn markings, chances are it's from a cap.

Personally I use 35V or 50V electro's on a -/+12V rail.
25V is a bit too close for comfort for me.
My rule of thumb is twice the rail plus 2 or 3V minimum.

To be on the safe side, I'd prefer checking the area around
the power connector first, before starting to swap IC's at random.
Or at least, remove the IC's from their sockets, and measure
the power pins of those first.

_g

> I second other recommendations to swap those IC, esp. if socketed, it is 
> really easy and fast. 25V cap would not likely be destroyed by reverse 
> power.
> 
> Tony
> 
> [Non-text portions of this message have been removed]
> 
>

then maybe somehow channel 4 does not receive power?


Bakis Sirros - Parallel Worlds / Interconnected / Memory Geist

[Doepfer_a100] group owner

www. parallel - worlds - music. com

www. myspace. com/ parallelworldsmusic

www. myspace. com/ interconnectedmusic

www. myspace. com/ memorygeist

www. DiN. org. uk

www. musicamaximamagnetica. com

www. vu-us. com

--- On Sun, 10/31/10, jonathan.heslop <jonathan.heslop@yahoo.co.uk> wrote:

From: jonathan.heslop <jonathan.heslop@yahoo.co.uk>
Subject: [Doepfer_a100] Re: Damaged A-143-1 Env/LFO Generator
To: Doepfer_a100@yahoogroups.com
Date: Sunday, October 31, 2010, 11:47 PM







 



  


    
      
      
      Now why didn't I think of that :) I tried swapping all 4 chips from channel 3, No joy though.



I'm guessing channel 3 and 4 chips are identical?!?



Jonathan



--- In Doepfer_a100@yahoogroups.com, Florian Anwander <fanwander@...> wrote:

>

> Hello

> 

> if the chips are socketed, try swapping the chips of pcb 4 with other 

> pcbs. I suspect 555 to be dead. TL082 usually survive wrong powersupply 

> at 12V.

> 

> Florian

>





    
     

    
    


 



  






      

[Non-text portions of this message have been removed]