Un-fry my ts-9...

[m_charles]

Hi Guys,

I rebuilt a ts-9 that had been hit with an incorrect power supply and fried (long foolish story). Fried to the point of burnt electronics smell etc.

I decided to just rebuild almost from scratch. I replaced every transistor with the exact same one (via smallbear). The FETS as well, and of course the op-amp, the electros and the .22 tants. Replaced all diodes except the 1 zener and the clipping pair. Did not replace the "regular" caps, or any resistors.

It works fine, just one problem. When bypassed, the buffered bypass is fine, but if you turn the volume, or the tone up to around max, a not-so-slight distortion creeps into the bypassed signal. I can't find any other obvious causes. Could it be the the "regular" caps I didn't replace? The  zener? The clippers? seems weird that they would cause this in the bypass.

Anyone's wisdom would be apprieciated! thanks,

Chuck

[MartyMart]

Sounds like the common problem that Boss SD-1's can have, some OD signal is
"bleeding" into the clean bypass.
Check around the fets that do the "flip / flop" switching for bypass, you may just have
a "whisker" of solder - enough to give you some signal bleed.
You'll need a magnifying glass, also remove any "flux" aroud that area too.
If all else fails, look up the SD-1 bypass fix, that envolves one additional fet/cap/diode

MM.

[MKB]

Perhaps another thing to try is to replace the connections to the volume pot with shielded wire.  I did this simple mod on my SD-1 and it stopped 90% of the bleeding.  However, the SD-1 bypass fix mentioned by MartyMart should eliminate the problem.

[m_charles]

thanks guys,

but this isn't a common problem on a TS-9 right? I just mean, most likley I made an error somewhere, correct?

As opposed to an sd-1 which is known for this. Could it be those other caps? I will hit it with a magnifing glass as suggested. thanks guys,

Chuck

[TheBigMan]

I grant you it's most commonly associated with the SD-1, but the TS-9 has certainly been reported with that issue.

[ubersam]

Why not do a hardwire bypass on the thing? It is a bit of a challenge to install a 3pdt on the TS9 box, but it can be done.

[m_charles]

thanks guys.

So noo ne thinks its the zener?

BTW, what the h#$l does that zener do anyways???

c

[ubersam]

IIRC, the zener bumps down the voltage for the indicator LED.

[TheBigMan]

IIRC, the zener bumps down the voltage for the indicator LED.

Yeah, it serves as the low battery indicator by cutting the LED if the supply is below a certain voltage.