Help reviving vintage electric mistress

[jer]

ok first of all this is my first post,so
HI,  I'm Jer, im 24 years old from buffalo ny and i enjoy long walks on the beach...
ahem
anyway

i just picked up a vintage deluxe electric mistress flanger on e-bay "as is"
meaning not functional.
so far i've figured out/observed:
--signal passes through on bypass but the pedal is completely dead when switched on
--It's not the switch, pots or any of the wiring, and power is coming from the transformer
--the delay circuit(sad1024) is getting power to it

where do i go from here?
one of the faq's (geo i believe) recommends replacing all the electrolytic caps
what happens if i can't find a direct replacement
for example one of them is rated at 200 mircoF 15v
do i want to use a higher or lower voltage and capacitance ratings?
if i dont use an exact replacement...will that harm anything or affect tone?

ill probably come up with more q's
thanx in advance for the help

[Peter Snowberg]

Welcome Jer,

I would say first build an audio probe. That's basically just a probe connected to a small cap like a 0.1uF and then to your amp. That will allow you to see how far the signal makes it through the circuit before stopping.

With any luck, that will point to exactly where the problem lies.

If you search for "audio probe", you'll find more info.

When it comes to caps.... electrolytics will dry up over time so replacement is good, but don't worry too much about the values. Typically, electrolytics have a tolerance of -20% to +80%. Just choose the closest value and you should be fine. A 220uF would be more than close enough for a 200uF. I always thought higher voltage ratings were just better but somebody posted here about not going too high when it comes to electrolytics. 35 or 50 volt caps would probably be best, but as long as you don't use a lower value than the original, it will be fine. 450 volt electrolytics should probably be avoided here, but they'll still work.

I don't have that schematic handy, but any big cap (like that 200uF) is for power supply and won't affect the tone. Crucial tone caps are usually 22uF or less. The really crucial ones are less then 0.1uF.

Best of luck on your repair and please do post any questions. I'm sure you will be the happy owner of a working pedal pretty soon.

Take care,
-Peter

[jer]

thanx peter
ill probably assemble a probe tomarrow

im sure that'll be a huge help tracking down the problem
ill keep you updated
Jer

[jer]

the audio probe works wonderfully
i found the problem right away...
whoever had the pedal before me apparently rewired it and in doing so wired the switch wrong
i check the switch to make sure it worked but i couldnt tell if it was wired properly until i made the probe

now the pedal works...although it sounds a little off...
i'm hoping that it's just the trim pots
i found a thread here that goes into detail on their adjustment so i should be all set
thanx again
jer