Danelectro Sitar Swami pedal need schematic

[RMD]

All,
I have a Sitar Swami pedal that, when engaged, produces a slow, swirling, swooshing sound with no guitar signal present. When clicked off, the pedal passes the guitar signal through as it should. The LED does turn on en engaged, but nothing else seems to work. Inside the pedal is pretty complicated, would definitely need some technical literature to service. Does anyone have a schematic for this pedal?

[Mark Hammer]

Anything you could provide about the chips or transistors used inside? I'm guessing there is a daughter board with the switching crcuitry, but what's on the main board?

[dwmorrin]

ElectroSmash - Sitar Swami Analysis
This blog has probably the most complete analysis of the sitar swami you'll find. Hope it's what you're looking for.

[flyingdutchman]

Looks like a tough nut to crack.

Anyway, my guess is that the processing section is working (probably the effect is achieved with a combination of phasing/flanging and delay) and the sound you hear is processed noise, i.e. the input signal gets lost before it gets to the processor. Check out the switching circuitry (4053) and any opamps in the vicinity.
A quick check on opamps is to measure the voltage on the outputs, these should be about half the supply voltage. If you find and opamp with its output stuck near 0V (ground) or the supply, you have a good reason to be suspicious of the opamp or its associated circuitry. Although, sometimes opamps are used as comparators and in this case the above described behavior is expected.

You'll want to have a 'scope and a signal generator handy.

[RMD]

Thanks for the replies. I plan to get back in there with function generator and scope soon. Also, I have requested service literature from Marcy at Dano. If they send anything useful I will share it.

[RMD]

So, in the end, the problem with the Swami pedal was an off-value (extremely off-value) chip resistor. It is stamped "103" meaning 10k Ohm. My signal tracing lead me to the vicinity, but having no schematic (thanks for nothing, Marcy), I was following a hunch. I lifted the chip to measure, and found the value closer to 2Meg. So, I soldered in an old-fashioned 10k as a temp, and the pedal started to produce that not-too-sought-after Sitar Swami droning sound, effecting my guitar's signal as it should. Got the chip resistor on order for a staggering 8 cents. Plus 8$ shipping (thanks Newark). I soldered an orange LED in place of the original red one, to match the pedal's color scheme.
It really is a cool, though un-sitar like sounding effect, after all.
Rob

[dwmorrin]

Great to hear you didn't give up! Fixing stuff without a schematic always makes me feel like I know something about something. Thanks for sharing the good news. Not surprising that Danelectro couldn't find any service info for you.