old pedal acting oddly.

[Chickenwings]

Ive got this 1981 MIJ SD-1.
It works fine, except that when i engage the pedal it takes a second or two for the signal to go through. Its like it needs to warm up or something.
What would cause this kind of behaviour? Any ideas?
All my other boss pedals turn on immediately.

 

[Little Pigbacon]

Re: old pedal acting oddly.

Is that every time you engage the effect, or just the first time after having it powered up?

 

[Funkfingers]

Re: old pedal acting oddly.

Speaking of which, how are you powering the offending pedal? Battery or mains?

 

[Chickenwings]

Re: old pedal acting oddly.

all good fellas. i have worked it out. It was pilot error when doing a mod so it would run on modern 9v power supply.
I took out a diode and resistor so i could run it on regular 9v psa adapter like the rest of the pedals. Old boss pedals have two components that modern ones dont use because they used to use 12 power supplies.
I should have put jumpers in to replace the parts.
I have put the jumpers in and now it works like the modern pedals.
Thanks for the quick replied fellas, but it fixed up now.

 

[Funkfingers]

Re: old pedal acting oddly.

I took out a diode and resistor so i could run it on regular 9v psa adapter like the rest of the pedals.

This tiny detail is more than a little germane to the question. It really should have been mentioned in the opening post.

Fortunately, all's well that ends well.

 

[Chickenwings]

Re: old pedal acting oddly.

yeah. id forgotten id done that. I was months ago and i usually just use a battery

 

[Brandenburg]

Re: old pedal acting oddly.

yea.. assuming its stock unless the owner of said pedal says otherwise

now my old effects rack does something similar to what the op said but thats normal for it though

 

[Chickenwings]

Re: old pedal acting oddly.

turns out that was not the issue.
It seems to need time to "Warm up" once its going it switches on and off, but slower than my other pedals.
If its been off for a while tho, it takes ages to get itself working.
maybe q1 and 2?

 

[Hank-]

Re: old pedal acting oddly.

Can dying electrolytic caps cause this behaviour? On a similar note, should those be changed out every 10-15yrs, the way amps are recapped?

 

[GoldenVulture]

Re: old pedal acting oddly.

I'd go for the electrolytic caps in there first, especially if it's old. Like the big ones, they dry out over time and stop working properly. There's a couple in there that pass the signal, or should.

If it's this circuit, there's three altogether.
- http://www.hobby-hour.com/electronics/s/sd1-super-overdrive.php -

 

[Securb]

Re: old pedal acting oddly.

FWIW Gibson175 your signature is going to give someone a seizure

 

[Chickenwings]

Re: old pedal acting oddly.

yep. just did all the caps.
Its still acting weird.
ive resoldered every suspect looking solder join and even cleaned, then replaced the switch.
Im starting to think it might be the jfets running the switching circuit?
Perhaps i cooked one? I dunno. Its odd and no matter how much googling i do i cant find anyone else coming across this "slow to get going" thing.


securb...i fixed my sig to something a bit more tame

 

[GoldenVulture]

Re: old pedal acting oddly.

Q3 and Q4 do the switching. Q1 and Q2 are controlled by them. Jfets are usually pretty cheap to replace.
Chips can die pretty easily from static from your hands while working on them. Once again 4558's are pretty available or an Equivalent.

 

[Chickenwings]

Re: old pedal acting oddly.

ive got some chips. ill try that. If that doesnt work ill order some jfets

 

[Chickenwings]

Re: old pedal acting oddly.

yep looks like it was the chip. It switches on and off fast and punchy now. ive tried plugging it in and running from battery to ac power a bunch of times. Its seems to be holding up.
Its a shame the pedal is no longer original from 1981 with the new caps, the ac adapter mod and the snazzy burr brown chip, but it sounds like it should and should keep punching for another 34 plus years.