Danelectro FAB Overdrive Schematic

[mimmotronics]

Traced out the audio path for a Danelectro FAB Overdrive the other day, here's the circuit.

https://stompboxelectronics.com/wp-content/uploads/2023/09/Danelectro-FAB-Overdrive-Schematic.pdf

Since the pedal is surface mount I wasn't able to correctly identify the values for some of the capacitors.

Also, I have the switching circuit traced out too, but it's handwritten so if anyone stumbling on this post needs that let me know. I'll probably scan it in sometime soon.

In short, the switching circuit is just a 4013 D Flip Flip triggering a 4053 analog switch.

[Rob Strand]

I traced this years ago but my hand drawn schematic is archived.

The main point about these FAB pedals is you should include the input buffer in order for it to work correctly.  In some cases the output buffer may also be required.

Maybe re-check your trace against these markups:

[obsolete version see update in later post]


[obsolete version see update in later post]
[Unfortunately the connection dots are missing because I did a screen capture.  Also HEF4053 not HFE4053]

[mimmotronics]

You're right, there are a couple buffers on the second PCB (the one I didn't trace)! I'll redo the schematic when I have the chance.

The one you posted isn't showing for me, oddly :/

[Rob Strand]

You're right, there are a couple buffers on the second PCB (the one I didn't trace)! I'll redo the schematic when I have the chance.

The one you posted isn't showing for me, oddly :/

You can try the direct links:
[obsolete version see update in later post]
https://postimg.cc/fJYxH2HJ
https://postimg.cc/G8KC72J2

There's a few other fixes on these and some cap values.

From memory, the cap values are from part measurements.  I have a feeling I had some cap values estimated from frequency response measurements.

FYI,Clay Jones put this up way back in 2006,

[mimmotronics]

Awesome! Didn't realize there was already an initiative! I was planning on tracing the FAB Tremolo & FAB Chorus too, I'll have to see what's already done.

[Rob Strand]

For the sake of correctness I've fixed a few things.  The C10/C11 values were bugging me so I checked the real unit (my old trace is archived).  Your original values were correct.


https://i.postimg.cc/zVjdCBPF/FAB-D2-Overdrive-fx-sch-Rob-S-markup-V11-2023-09-08.png


https://i.postimg.cc/JtcwFR2G/FAB-D2-Overdrive-switch-buffer-board-V11-2023-09-08.png

I was planning on tracing the FAB Tremolo & FAB Chorus too

I haven't seen schematics for those, or traced any.  The FAB Chorus is a PT2399 based unit should be easy although the details on the clock modulation would be need to be checked carefully.  (I'm not aware of a FAB Tremolo.  Is that one of the FAB series?  For the other Danelectro series pedals there are schematics on-line.)

I traced the Flanger many years ago.  The tracing is on a piece of paper somewhere and packed away - I hope I haven't lost it.   Never got around to drawing it up on CAD and checking the fine details.

IIRC, the Switching/Buffer/Mixing board on the Flanger is different to the Chorus.  I believe the Chorus uses the opamps in the PT2399 chip for mixing, whereas the Flanger uses a separate opamp.   Something like that  .

Here's the Tuna Melt tremolo from the DJ "Food" series.   I call them the "Owl Face" enclosures.

Danelectro Tuna Melt (DJ-5?) - Tremolo

Thread
https://www.thegearpage.net/board/index.php?threads/danelectro-tuna-melt-tremolo-re-housing-guide-2.202746/page-2

Schems
https://imgur.com/7ZA28yF
https://imgur.com/k0zNJ8c

Obviously b and c need swapping on Q2.

[PRR]

> Obviously b and c need swapping on Q2.

Agree.