I dun goofed - any help?

[Agileguy_101]

I accidentally screwed with the IC trimpots on my Memory Boy, not knowing what I was doing. I know that I can send it in to EH and have them fix my error of stupidity, but I'm kind of broke. I might be able to get my hands on an oscilloscope, and my dad has used them before, so he could help me. Any advice on what to do?
If I can't get an oscilloscope, is there anything I can do short of sending it back to EH?

[trevorus]

Re: I dun goofed - any help?

Well, question is, do you remember how much you moved them? Second, even if you had an o-scope, do you think you would be able to actually diagnose what is going on? What's the pedal doing right now?

[Agileguy_101]

Re: I dun goofed - any help?

Well, question is, do you remember how much you moved them? Second, even if you had an o-scope, do you think you would be able to actually diagnose what is going on? What's the pedal doing right now?

No and nothing. When I turn it on I get no output.

[trevorus]

Re: I dun goofed - any help?

You may be SOL there. Send back to the people that built it. They know the design and know exactly what those little trim pots do.

[dr. ad]

Re: I dun goofed - any help?

good on you for lining up an oscilloscope tho
respect.

[Vasshu the humanoid typhoon]

Re: I dun goofed - any help?

^But what good will it do him again??

[dr. ad]

Re: I dun goofed - any help?

he was still thinking ahead

; ]

[Vasshu the humanoid typhoon]

Re: I dun goofed - any help?

.....hehe take a course in basic electronics then!
And trim those BBD's back, plus what else he might have knocked out on the bias knobs.

[Boppy]

Re: I dun goofed - any help?

Even if you did get an oscilloscope you would still need a spec-sheet to calibrate it to factory default. Maybe dick around with the trim pots again until you get a signal and then just try to set things to right by ear--that is if you didn't fry the chip by diming the bias pot. Hope it works out. Let us know how it goes...

[The JEM Ghost]

Re: I dun goofed - any help?

Above post is what I'd advice as well.
Without a spec-sheet an oscilloscope would not do him much good, another option would be to measure voltages across certain points, but without reference values from a spec-sheet, it's not going to solve anything either.

Carefuly going by ear, while avoiding extreme pot settings and hoping you don't fry the chip seems the best option.

[Vasshu the humanoid typhoon]

Re: I dun goofed - any help?

Fry the chip....
How so??
Just get it send back to where it came from and get it biased back
But you can dial it back by ear(well most of it)
Rule of the thumb.....put a mark from where the trimmer was, the next time you wanna fool around inside those things

[GoldenVulture]

Re: I dun goofed - any help?

Mid point is a good place to start if you've no reference. Do the adjustment with the pedal off. Turn it on and seek from there. It may require turning it off and back on [ The power ] before adjustments register.

[Boppy]

Re: I dun goofed - any help?

By goofing around with the bias-pot you can toast the output section of the op-amp chip by making it work too hard. Phzzzzzzzt...goodbye chip, hello expensive repair bill.
Sucks if it happens to a vintage effect.
Anyways, to the OP, set all the pots to noon (or as close to pre-messing around as you can remember), see if you get a signal, and then try to set it by ear...
By the way, goofing around with the trim-pots toasts something else too...your warranty.

[Vasshu the humanoid typhoon]

Re: I dun goofed - any help?

Since when where OP-Amps in massproduced pedals expensive?
Look like this??
No output on a religiously bypassed pedal?
Is there output in bypass??

[saladin]

Re: I dun goofed - any help?

No output on a religiously bypassed pedal?

Laughed so hard I nearly fell off my chair!