1978 Deluxe Electric Mistress problem

[Ed22]

Hi everyone,

I have an old Deluxe electric Mistress flanger (1978 i think), transformer inside. I have a problem with it. it does not work properly.
When by-passed, signal is OK.
When effect is on, sound is very very low. I mean what i hear is the wet signal (have to raise the volume of the amp: about 5 on my princeton) but i also hear the waves of the flange (like vzzz....vzzzz...vzzz...vzzz       sorry not so easy to describ by words! ;+) ).
I've mesured some voltages: SAD1024 has its 14V on pin 9, 741 has also 14V on pin 7. So i don't think it comes from power.
I thought of a bad capacitors...
i can post pics if someone asks.
I don't think it's a really bad issue, but anyway, i have to find it, as i love this sweet pedal.

thanks for any kind of help.

cheers,

Ed.

[theehman]

I would audio trace the pin 6 of the 741 and pin 1 of the 4558.  Your signal passes through the 741 then the 4558 before it gets to the SAD.  Since you can hear some swooshing it sounds like the SAD is OK but doesn't have anything to work with.

[Ed22]

Hi theehman,

you're probably right (i don't want the SAD to be the culprit ;+)) . I have no scope, just a DMM. audio-probe would be ok?

thanks,

Ed.

[theehman]

Audio probe should be fine.  That's what I always do.

[Ed22]

Ok,

I've diy an audio probe, with some music playing from the output of my soundcard.
At the very beginnig of the circuit, sound is clean.
then there is still sound at the input and output of the 741 (but a little saturated).
then i've checked the 4558. at input, i can hear the sound flanged. refering to the schematic of the mistress (hand written and dated 12/28/77), at pin 7 of the 4558 (output), there is almost no sound or very very very very little volume... 4558 has a problem?

thanks,

Ed.

[theehman]

I'd replace the 4558 and see what happens.

[Ed22]

Just to give a best description:
for the 4558:
at pin 1: sound is good (a few saturated)
at pin 2: very high frequencies (not sweet to hear!)
at pin 6: i can hear the flanged sound.
at pin 5: nothing
at pin 7: almost nothing (which is quite strange, as it should be the output to jack...

hope that will help.

cheers,

Ed.

[Ed22]

sorry, i've just seen your message.
Ok, this 4558 seems to have a problem.
but one question: is it possible that some pin work on an IC, and others not?

thanks,

Ed.

[theehman]

It could happen.

[Ed22]

I've changed the 4558... it brings my Mistress to life 
added a socket...for the next 30 years  who knows...

thanks a lot for your help,

cheers,

Ed.