minnow

[djmiyta]

I had a transistor in wrong way . Now I get by-pass signal but no wet signal I'm unsure what do Does the pedal need adjusting and is that what the trimmers are for?

 

[andare]

Yes the trimmers must be adjusted correctly.

 

[djmiyta]

Yes the trimmers must be adjusted correctly.

Can you tell me how or what to do? Although now I've got a problem with it but once fixed still need to do the trimmers so if you could help out I'd appreciate it
Thanks

 

[Mcknib]

You'd set the trimmers by ear

The ggg Maestro Filter Sample/Hold Replica Instructions gives notes on setting the trimmers

Note their version uses 2 x CA3080s instead of an LM13700 which is 2 x CA3080s in a 16 pin package and different FETs etc so you'd need to compare schematics to make sure the Q numbers are the same if you plan on using their voltages etc for further troubleshooting

Maestro Filter Sample/Hold | General Guitar Gadgets

www.generalguitargadgets.com

GGG is a good resource for finding voltages, if I can't work them out I always check to see if they do the same circuit you'll usually find sample voltages in their build docs

 

[djmiyta]

You'd set the trimmers by ear

The ggg Maestro Filter Sample/Hold Replica Instructions gives notes on setting the trimmers

Note their version uses 2 x CA3080s instead of an LM13700 which is 2 x CA3080s in a 16 pin package and different FETs etc so you'd need to compare schematics to make sure the Q numbers are the same if you plan on using their voltages etc for further troubleshooting

Maestro Filter Sample/Hold | General Guitar Gadgets

www.generalguitargadgets.com

GGG is a good resource for finding voltages, if I can't work them out I always check to see if they do the same circuit you'll usually find sample voltages in their build docs

Thank you very very much

 

[bowanderror]

Can you tell me how or what to do? Although now I've got a problem with it but once fixed still need to do the trimmers so if you could help out I'd appreciate it
Thanks

The two trimmers are HIGHLY interactive (as in adjusting one changes the range of the other), so you'll have to be a bit methodical in how you approach the calibration. I haven't quite found the sweet spot on mine yet, but here is the info I've been using to set my trimpots:

From the calibration instructions from the Madbean version:

1. T2 sets the “Intensity” of the S/H & T1 sets the “Range”
2. Start with the Speed & Resonance controls about 2/3s of the way up & the Mode switch set to S/H mode (the other knobs don’t matter since they have no influence in this mode). T2 should be fully counterclockwise & T1 about 1/3 of the way up
3. Adjust T2 clockwise until you hear the stepped filter sound
4. Now adjust T1 to alter the range of the steps - You will hear the filter sweep through a lot of up & down steps while this is going on
5. The key here is to adjust the trimmers until the number of up & down steps is about the same. In other words, they don’t concentrate too heavily on the top or bottom end of the filter sweep

The two trimmers are interactive and you will probably find yourself dialing the S/H a few times as you get used to the sound of the effect. Don’t be afraid to adjust it as much as you like. You can get some very interesting results with very subtle adjustments.

 

[djmiyta]

The two trimmers are HIGHLY interactive (as in adjusting one changes the range of the other), so you'll have to be a bit methodical in how you approach the calibration. I haven't quite found the sweet spot on mine yet, but here is the info I've been using to set my trimpots:

From the calibration instructions from the Madbean version:

1. T2 sets the “Intensity” of the S/H & T1 sets the “Range”
2. Start with the Speed & Resonance controls about 2/3s of the way up & the Mode switch set to S/H mode (the other knobs don’t matter since they have no influence in this mode). T2 should be fully counterclockwise & T1 about 1/3 of the way up
3. Adjust T2 clockwise until you hear the stepped filter sound
4. Now adjust T1 to alter the range of the steps - You will hear the filter sweep through a lot of up & down steps while this is going on
5. The key here is to adjust the trimmers until the number of up & down steps is about the same. In other words, they don’t concentrate too heavily on the top or bottom end of the filter sweep

The two trimmers are interactive and you will probably find yourself dialing the S/H a few times as you get used to the sound of the effect. Don’t be afraid to adjust it as much as you like. You can get some very interesting results with very subtle adjustments.

Thank you very much for this. I have a question though , on your build did you have an audible signal as soon as you tested it? What I mean is did you have to adjust your trimmers before you heard anything from the pedal? cause right now I have by-pas signal but when engaged no wet signal. So if I should be hearing something right off then I've got an issue or 2> As is ,my preliminary voltage readings are wwwwwwwayyyyyy off. I figured I got a wrong value or 2 on the board but I checked the board found 1 wrong valued cap changed it and from there both LED'S worked. I was hoping that adjusting the trimmers might bring up proper voltages else where cause I'm not getting 9v out of the max1044
So again will adjusting the trimmers bring in an audible signal or should one already be there?

 

[djmiyta]

Here are my crazy nonsensical Minnow voltages. I thought the Meat ball was tough! I've been going full bore trying to figure this out if any one could take a look and maybe give me an idea where to even start? Much appreciated

 

[bowanderror]

Thank you very much for this. I have a question though , on your build did you have an audible signal as soon as you tested it? What I mean is did you have to adjust your trimmers before you heard anything from the pedal? cause right now I have by-pas signal but when engaged no wet signal. So if I should be hearing something right off then I've got an issue or 2> As is ,my preliminary voltage readings are wwwwwwwayyyyyy off. I figured I got a wrong value or 2 on the board but I checked the board found 1 wrong valued cap changed it and from there both LED'S worked. I was hoping that adjusting the trimmers might bring up proper voltages else where cause I'm not getting 9v out of the max1044
So again will adjusting the trimmers bring in an audible signal or should one already be there?

If you switch it from Sample & Hold to Envelope mode, the trimpots won't have any influence on the circuit, so you can use that to test if the audio is working.

I'm assuming IC3 on your voltages is the TC1044 charge pump, and you're getting the right voltages on Test #2: 9V from pins 1&8, and -9V from pin 5. I don't know what is going on with the other tests as many of the voltages look like your ground DMM probe fell off or something. Where exactly are you connecting the ground probe of the DMM?

I would first try re-seating all of the ICs in their sockets, and doing the same with your JFETs. For inserting JFETs into sockets, try straightening the leads first, then inserting it into the socket so the outer leads "squeeze" the inner side of their sockets. I've had issues with pre-bent leads not making good contact with sockets.

Normally, the readings of the charge pump shouldn't be affected by whether or not the JFETs are hooked up, so the problem is likely somewhere else in the circuit. The drains of Q1 & Q5 should be +8V and +9V, respectively, so reading somewhere near 0V is a red flag.

You may want to try audio probing the audio path, starting with your input jack. With the footswitch "On", you should be able to trace the audio through the PCB and find out where it drops out.

 

[djmiyta]

Thank you so much for taking the time to look at this.I have no idea why on 1 test only was I able to get proper readings from the 1044. I figured without that working none of the rest of the circuit would be working. So if an IC or tranny was not seated properly it should not affect the 1044 IC for it to give the right voltages? And I understand those 1044’s can’t take anything at all over 10 v even if my supply is 9.27v do you think a wrong value on the pcb could fry that IC (even though I put a new one in) just curious if it’s possible and to audio probe this circuit do I not need the charge pump and voltages to be right first or just power it up and start probing?

 

[bowanderror]

Thank you so much for taking the time to look at this.I have no idea why on 1 test only was I able to get proper readings from the 1044. I figured without that working none of the rest of the circuit would be working. So if an IC or tranny was not seated properly it should not affect the 1044 IC for it to give the right voltages? And I understand those 1044’s can’t take anything at all over 10 v even if my supply is 9.27v do you think a wrong value on the pcb could fry that IC (even though I put a new one in) just curious if it’s possible and to audio probe this circuit do I not need the charge pump and voltages to be right first or just power it up and start probing?

9.27V straight off the PSU is fine as there is also a Schottky diode in series with the DC input, which will drop an additional 0.3-0.4V across it.

If the TC1044 isn't seated properly, that would definitely affect the voltages, but the other ICs and transistors are less likely to cause global voltage changes - Unless there is a short somewhere, which I wouldn't rule out in this case. Being that the voltages are so inconsistent, maybe it's best if you post some close-up pics of the top & bottom of your PCB. There may be a solder bridge or burnt trace that we can spot. Try to place the board in good lighting and take pics at a few angles if there is glare.