SOLVED Acrobat - filter section not working

F

ftumch

Active member
Wonder if anyone can help

My Acrobat is passing signal and the distortion works, but I have no action on the filter section

Turning the 'height' control to the right attenuates the output

The 'bandwidth' control is seemingly inactive

The 'freq' control might be doing a little something but it's difficult to say

I've used this particular 2p6t rotary set to 5 positions: https://www.switchelectronics.co.uk/products/2-pole-6-way-rotary-switch-splined-shaft-pcb-terminals

I did a continuity test on the rotary and it seems to be making sensible connections around the daughterboard as it turns

I've checked for continuity on the IC pins through to the back of the board

I've reflowed my solder joints and double checked the component values

Bit stuck now without a schematic

Thanks in advance
 

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Make absolutely sure no component leads are puncturing this electrical tape. (on either dual gang pot)

It is almost always the dual-gang pots and electrical tape is almost never good enough, despite it looking like it's insulating properly.

I'll get a schematic for you shortly. It might already be posted around here somewhere.

1748639379897.png
 
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Just to make sure: the effect is hard to detect in some settings i.e. in the widest q (CCW selector) position and/or with height (right knob) near noon. The fact you are getting signal cut in the height may flag a working pedal because that's what it does.

Test to make sure: distortion/gain on, q selector fully clockwise, height (right knob) fully cw. Strike a chord, rotate freq (left) knob, you should hear a very pronounced envelope wah sound .

The other thing that might be happening is you put too many notches in the selector knob and it's wrapping around to first q position fully CW. Just noticed this on mine. So also try the 2nd and 3rd CW positions from the end.
 
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Cheers @comeradehoser I hadn't thought to remove the washer and try the other positions

I'm getting no filter sweeps in any position on the rotary

One thing I noticed is there is a popping sound when the rotary goes between positions 5 and 6, so something is connected somewhere
 
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Well, might be the rotary Or traces thereof. Sounds like the other knobs are working, and the q is what's missing.

I've also broken rotaries installing them into enclosure (crack).
 
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comradehoser said:
Well, you can see them, particularly out of box. If you search, I helped with some traces of the switch in another acrobat troubleshooting thread.
Click to expand...

I searched for your thread mate but I can't find it

The switch itself functions properly and the pins are all connected to switch contacts, but the common pin circled red in the photo here doesn't seem to be connected to anything

I tried bridging the common pins together and that changed the behaviour of the height control but still no filter sweeps

Any idea what this pin is supposed to connect to?

PXL_20250602_131221815.jpg
 
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It's here

C

Thread 'Acrobat Parametric Distortion'

I think this might be my first "proper" build report--not a PTP.

It's not particularly exciting--There really isn't a lot of extraneous skilled stuff to show off with like tidy off-board wiring--this thing was titetitetite. I have to say, I don't think I like board-mounted jacks much, but that might be a function of the fact that I hand-drill all my enclosures. The nice white enclosure was because stompbox parts didn't have any bare aluminium ones in stock. I did put some nice knobs I sourced at Lee's Electronics last time I was home on there so it would look good, but as is usually the...
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Sorry, it was for the height pot I traced, not the Q selector.

Yeah, I think you'd have to be able to see the traces on the other side to suss out if there is a continuity issue. But you could just run a continuity check and see what shakes out, particularly if there is any shorting going on between pads.

It's a bit hard to see in the pics. Some of the solder looks *awfully* cozy between the top rotary switch pads on the knob side.
 
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Since the switch is symmetrically arranged, I would imagine that there should be a something on the pin neighboring the one with the X. I would bet it's the one with the X. That is perhaps your issue.

I think you could also check for continuity with the switch pins and the banks of resistors on either side or whatever other elements are connected to the poles and throws.
 
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Oh I was using this crazy solder from Ukraine that has an insane amount of flux in it. I started cleaning it off with alcohol and it turned into a sticky mess so I gave up. Combine that with brutal lighting lol. That solder is back in the drawer now

Coming back to the problem later it was obvious that I should try connecting the two red things that weren't connected to anything else - and that's fixed it

It sounds bloody marvellous, I love it already

Thanks for your help @comradehoser

I'll do a better job of this patch and get it boxed up :)

PXL_20250602_200109170.jpg
 
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Robert said:
Make absolutely sure no component leads are puncturing this electrical tape. (on either dual gang pot)

It is almost always the dual-gang pots and electrical tape is almost never good enough, despite it looking like it's insulating properly.

I'll get a schematic for you shortly. It might already be posted around here somewhere.
Click to expand...
Would it be still possible to get the schematic?
 
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