vintage MXR flanger dead SAD1024 ?

[artstomp]

...I bought a non working MXR 117 Flanger from ebay about a year ago...i cant get it to work...so i suspected the SAD1024 ic is non functional...the built in transformer was busted so i removed it...i replaced the the regulator LM34OT-15, C24 ( 400uf ) and connect
18v dc across C24...output voltage of the regulator is 15vdc..

..audio signal passes thru both bypass and on mode...when engaged there is audio signal from input but no flanging effect or whoosing sound...i have no way of testing the SAD1024 if it is working....so here are the voltage readings on the semiconductors...

pls. help...tnx


SAD1024

1   0v
2   1.5v
3   4.65v
4   0v
5   1.3v
6   3.5v
7   14.65v
8   1mv
9   0v
10   4.42v
11   14.65v
12   0v
13   3.8v
14   3.8v
15   .8mv
18   11.83v


U3   CD4013

1   1.1mv
2   .9mv
3   14.65v
4   0v
5   14.65v
6   .3mv
7   0v
8   14.65v
9   14.65v
10   2v
11   14.65v
12   3v - 14.65v
13   14.65v
14   14.65v



U1   CA1458

1   3.62v
2   3.5v
3   3.55v
4   0v
5   3.6v
6   3.6v
7   3.6v
8   14.65v


U2   CA1458

1   4.52v
2   4.48v
3   4.48v
4   0.2mv
5   3.78v
6   3.73v
7   3.61v
8   14.65


U4   CA1458

1   7.32v
2   3.5v
3   3.5v
4   .2mv
5   3.7v
6   3.9v
7   3.88v
8   14.65v


U5   CA1458

1   2.1v
2   7.5v
3   2v - 12v
4   0v
5   7.6v
6   7.6v
7   2v - 12v
8   14.65v

[Scruffie]

Sort of good news, it's not necessarily the SAD, there's quite a lot wrong there.

Heading out though so will have to check later if no one jumps in first.

[Scruffie]

So... starting with the SAD, you should have power going to pin 9 but don't yet you have it on pin 11 and some other slightly off readings, could you remeasure it as I think you might have some of the pins labelled wrong.

Your clock isn't working so your BBD can't work even if it's fine... tracing back to the LFO, on U5 does pin 1s voltage vary like pin 3 & 7? If it does moving on, are you using an analog multimeter rather than digital? Your OpAmp voltages all look right but very low so it may just be the low impedance of your meter giving false readings.

So... I think your problem most likely lies with replacing the 4013 (this tends to be the part to go) or one of the transistors between it and U5.

[artstomp]

Sort of good news, it's not necessarily the SAD

..that's actually good news!!...tnx scruffie...
..i'm using a SANWA CD800a digital multimeter...i will remeasure the voltages again...and will try to replace U3 and check the transistors...can i use the transistors used on the collosalus to replace the ones in the MXR flanger?...

..by the way i forgot to mention that i replaced also the 500k trimmer clock..and i dont think it was set correctly...

..tnx again

[artstomp]

..tnx Scruffie..my vintage MXR flanger is now ressurected!....here's what i did...i replaced the 4013 ic and still no flanging...so i decided to replace the 4 transistors...Q1 with the same transistor 2N4126 and Q2-Q4 with replacement ones BC549C as used in Madbeans collosalus...and voila!...watery flanging is now heard!...i replaced also the 500k clock trimmer and adjusted it...the other two trimmers' adjustemens are soldered and fixed so i left them as is....

...i ended up replacing C21 with 2 22pf capacitors in series (11pf) because the clock noise seems annoying and loud when the WIDTH knob is set between 10 o'clock and 2 o'clock...and quiet when set before 10 o'clock and past 2 o'clock....is this normal with the vintage Mxr 117 flanger?...

...should i replace C21 with 33pf only as the note says select between 33pf-62pf ?

tnx again Scruffie...

[Scruffie]

You shouldn't need to replace the clock cap unless it's drifted in value or leaky or dry, it was selected at the factory.

More likely is you need to replace all the electrolytic and tantalum capacitors.

Although the transistor swaps will have caused some change in delay time with different gains... do the cap replacements and then see how things are.

But congrats on the working flanger and non-dead SAD!

[artstomp]

...i'll try to swap the 4 original transistors one at a time with the replacements since i don't know which one is defective because i replaced them all at once...before i replace the electros and tantalum caps...

i will also put back the 33pf clock cap and see how it goes...i was really happy to know the SAD is functional..tnx scruffie

[artstomp]

..my MXR 117 now works fine and boy it sounds good after replacing all 5 potentiometers which causes all the noise and especially on the width knob....but NOW a TICKING sound although not so loud is annoying!...what seem to be causing this?..is there anything i could do to minimize it...

...33pf on the clock ic is still there...i didnt also put back the 4 original transistors as i planned to do...instead as ive said...i opted to replace the 4 pots which eliminated the noise....

tnx again

[Scruffie]

Your wiring could cause that, use shorter wires and make sure they're not crossing.

[artstomp]

...tnx Scruffie...took your advice and all is well now with my MXR 117...thank you very much..your the man!...
..my son is so overwhelmed with the sound the MXR flanger 117 makes!

[Scruffie]

  glad I could help and get a potential paper weight back in the musicians world.

[artstomp]

...i'd like to thank again scruffie for helping me fixed this MXR 117 flanger...enjoyed playing this baby but i noticed it tone sucks a lot and drops the volume too much when engaged...i just want to ask you guys whose got a hand on a vintage MXR 117 flanger if that is normal...
..or i think i need to ask scruffie again for a fix on the problem..tnx guys...

[Scruffie]

Have you replaced all the electrolytic and tantalum caps like I mentioned? That might help.

It isn't true bypass so, some tone suck can be expected, but it shouldn't be too bad.

[artstomp]

...i wasnt able to replace all the tantalum and electro caps...i really think that will help...by the way i replaced the original spdt sw with 3pdt sw and made it true bypass thats why the volume drop and tone sucking is eminent and noticeable...tnx scruffie