MXR - Auto Q [schematic]
- Dirk_Hendrik
- Old Solderhand
Information
Please let me know. Reversing is no option as I'm running toward a deadline. Will sign a NDA without a problem.
- fosnal1950
- Breadboard Brother
Alf
- Dirk_Hendrik
- Old Solderhand
Information
Thanks.
But I'm referrin to the new one which has been bitching me for a full sunday and, though improving from completely dead to less dead (does bypass again, does do audio in affect mode again), to "does not do envelope effects yet". Although there's similarities to above schem the new one has a lot more junk under the hood.
But I'm referrin to the new one which has been bitching me for a full sunday and, though improving from completely dead to less dead (does bypass again, does do audio in affect mode again), to "does not do envelope effects yet". Although there's similarities to above schem the new one has a lot more junk under the hood.
A customer brought one to me that wouldn't pass signal, but Dunlop was no help and wouldn't give up a schematic. They had a $50 flat fee repair (this was about 2 years ago), so I had the customer send it to them. Not sure if this is an option for you.
- Bernardduur
- Transistor Tuner
Checked out my DisumBOMBulator scheme? It is similar to the old MXR with some add-ons and more 'junk'.Dirk_Hendrik wrote:Thanks.
But I'm referrin to the new one which has been bitching me for a full sunday and, though improving from completely dead to less dead (does bypass again, does do audio in affect mode again), to "does not do envelope effects yet". Although there's similarities to above schem the new one has a lot more junk under the hood.
Maybe it helps
'No more....... loud music.......'
Follow my love for pedals and amps on https://bernardduur.blogspot.com and https://www.instagram.com/bernardduur1
Follow my love for pedals and amps on https://bernardduur.blogspot.com and https://www.instagram.com/bernardduur1
- Dirk_Hendrik
- Old Solderhand
Information
Thanks again.
I think I've got the bitch covered. Step 1 was no power. A burned 10 ohm resistor in the power line. Step 2 a dead 4049 (SMD naturally). Replaced and she could switch in and out again. Did filter but no quack, let alone wah. Replacing 2 Motorola TL074 like chips by LM324's made her quack again but rather distorted. I expect the replacements with real TL074's will do the trick.
No TL074's in tha house??? Plenty... but not in SMD... which I did for LM324's...
I think I've got the bitch covered. Step 1 was no power. A burned 10 ohm resistor in the power line. Step 2 a dead 4049 (SMD naturally). Replaced and she could switch in and out again. Did filter but no quack, let alone wah. Replacing 2 Motorola TL074 like chips by LM324's made her quack again but rather distorted. I expect the replacements with real TL074's will do the trick.
No TL074's in tha house??? Plenty... but not in SMD... which I did for LM324's...
- borislavgajic
- Opamp Operator
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no doubt you are going to fix that.......
cheers
boris
cheers
boris
- pz
- Solder Soldier
Does the new pedal still use PWM for the variable resistances?
I remember, while experimenting with PWM on my breadboard i used once LM324s and got ugly distortion (the chips were ok), which disappeared when i replaced them with 074's.
074 is a good chip
I remember, while experimenting with PWM on my breadboard i used once LM324s and got ugly distortion (the chips were ok), which disappeared when i replaced them with 074's.
074 is a good chip
- Dirk_Hendrik
- Old Solderhand
Information
pz wrote:Does the new pedal still use PWM for the variable resistances?
I remember, while experimenting with PWM on my breadboard i used once LM324s and got ugly distortion (the chips were ok), which disappeared when i replaced them with 074's.
074 is a good chip
yep.
The 324 is made for a single supply. The TL's, like most opamps for a dusal supply. Hence the ugly distortion when using them in place in a circuit with a virtual ground, like almost any 9 volts effect.
- Ice-9
- Degoop Doctor
Information
Sorry to resurrect an old thread but I was wondering if anyone managed to find a schematic for this (M-120 Auto Q). I have one on the bench now for repair. It is in a poor state after someone tried to repair it with very bad soldering around all the IC's. I have got it switching but the output signal is very low. I'm just going to go through the signal path with an audio probe but a schematic would really speed things up if there is one.
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !
No silicon heaven ? preposterous ! Where would all the calculators go ?
No silicon heaven ? preposterous ! Where would all the calculators go ?