Non-working A/DA Flanger

[mort]

Recently picked up this flanger. Bypasses signal fine but with the effect on it makes no noise except for a tiny little hint while sweeping the enhance control. Otherwise it's dead silent. I do know there's ~20v on the secondary of the t-former but do not know how to troubleshoot from there.

Some photos and details about this particular flanger...





There's been some sort of modification that looks like it may have been done at the fatory(?) The next couple of photos show an added resistor on the back of the board and one leg of the corresponding resistor moved over to another location. I'm kinda guessing this had to do with a revision, but I'm not sure. Need a little help with that too, please.







Has the MN3010 chip fwiw, and on the inside of the enclosure 10-205P is stamped/molded in.

So where do I start? I have some hobby background in tube electronics but I'm pretty green on this type.

[mort]

Just noticed that under the serial number sticker the board is labelled 10-185P. Seems that things were on the move at A/DA when this one was being built.

[MarshallJMP]

I attached the schematic of the 10-185P, must say never heard of a 10-205P version, there is a 10-186P and a 10-189P version.

You can check if you have the 15V supply voltage. You can measure that between pin 4 and pin 8 of the MC1458 opamp (the 8 pin chip).

Link to the datasheet  https://www.ti.com/lit/ds/symlink/mc1458.pdf?ts=1627978499602&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FMC1458

[MarshallJMP]

Some more schematics

[mort]

Maybe the 205P is just the housing (?)

I bought another non-working unit that should be arriving tomorrow that has the voltage controller pedal with it. Maybe between the two units I can get one working set.

[rnolan]

Hey mort, hope you get it sorted and end up with a working unit  :thumb-up:

[mort]

What is the voltage requirement for the early flangers that require a power adaptor? The one that just came in the mail is marked 12v and putting out 19v.

[MarshallJMP]

You actually need a 18V adapter. On the other hand you measure 19V but I guess you measured it with no load attached to it?