BOSS SD-1 Problem - HELP!!!

[PedalDude1]

I have a Japanese BOSS SD-1, black label pedal. I've been having problems with it lately. When I stomp on it, the LED comes on right away but the sound doesn't. The volume goes from nothing and swells up to normal volume. The volume swell can take anywhere between 0.5 sec to 5sec.

The problem seems to happen only after the unit has been in use for an hour or so.

I changed all electrolytic capacitors on the board but the problem persists. I suspect a problem with the switching buffer but I'm not sure.

Anyone here have a similar problem with their SD-1 or other BOSS effect?

Please help!!!

[Rodgre]

I'm sorry that I can't help, but I thought I'd bump you to see if anyone else can...

Roger

[Fret Wire]

If you already changed the electro's, it seems to be a switch or Jfet problem. Does this occur with battery power, power supply, or both? Is your's an ACA power supply model? Using the newer PSA power supply on an older ACA pedal can get poor results sometimes. You can easily convert it to use the later PSA regulated supply.

[PedalDude1]

The problem happens with both Battery power and Adapter.
the voltages on the board seem fine everywhere.
Do the JFETs tend to slowly degrade over time? Maybe I should try changing those...

[wampcat1]

I had the same problem with a boss ds-1 quite a while ago, but I gave up on it! I ended up just selling it 'as-is' on ebay. They are so cheap to buy, its (IMO) almost not worth trying to fix!

Thanks,
Brian

[PedalDude1]

Do you remeber what you did to try and fix it (so I know what doesn't work)?

Thanks,
F.M.

[wampcat1]

Do you remeber what you did to try and fix it (so I know what doesn't work)?

Thanks,
F.M.

I changed a few caps that I thought might be causing the problem, but didn't have any luck. At that point, I just stuck it in a drawer, and listed it on ebay.

Thanks,
Brian

[dolhop]

Do you get the problem both ways (on and off) or does it only happen when turning on?

When you have it open and plugged in, measure the gate voltage on each of the FET switches and see how long they take to get to steady state.  It definitely sounds like a switching problem, though I wouldn't accuse the FETs just yet - they don't degrade - they die.  In that case, you wouldn't get anything.

[PedalDude1]

The problem happen only when turning ON.
I'll try changing the FETs, see if that solves my problem.

[dolhop]

check the CR combos in the switching area.