ACA adapter vs DSD-2

[sebastien32]

Hi,

I bought a DSD-2 some time ago and the seller gave me the adapter that he was using with the pedal. turns out it was a ACA-120. At first, I was happy.. a free ACA adapter...

Fast forward to yesterday when I realize that this pedal requires a PSA adapter. So I tried the pedal again but with a PSA adapter this time (first time since I bought it at the seller's house where it was connected using the ACA adapter). The pedal seems to be fine as far as I can tell.

Was I lucky or this pedal is protected internally?

[laurie]

Fortunately, the power supply circuitry in the DSD-2 is very slightly different to the DD-2 and this might have saved any damage.

If it was a DD-2, the D6 Zener diode would likely have overheated and either burned out or caused damage to circuit traces (a common cause of failure in the DD-2).

In the DSD-2 the equivalent diode is D21 and it is a regular diode so it avoids the D6 problem.

The ACA supply will have been powering stuff that is nominally expecting 9VDC with around 12VDC. The opamps will be fine. I checked the ratings of the BA634 flip-flop (16V) and NE570 compander (24V) so they should be OK.

The 78L05 may have overheated due to the higher input voltage... but if it is still working it is likely OK. C54 may have been run near it's voltage limit, but again, if the pedal is working it is likely OK.

I *think* you will be OK... i.e. "you got lucky"

[sebastien32]

Thank you for the detailed explanation. I'm glad that the pedal seems to be fine. This one is in near mint condition. I will compare it soundwise to my DD-2 to see if I can find some problem with it.

[laurie]

No problem.

FYI - if any of the potentially damaged components had failed, the pedal likely wouldn't work at all, or it would sound terrible.

I believe that if it sounds different to the DD-2 that won't be because it was used on the ACA adapter...

[Pepe]

That's good information, Laurie! I didn't know that the DSD-2 has a slightly different power supply circuitry.