Build Your Own Clone Message Board

I have this exact issue with mine. I double checked locations for all resistors and capacitors along with the wiring itself. As far as i can tell everything appears to be in place.

I noted another thread here about a large batch of bad IC chips so i went ahead and ordered a couple 20 counts of the TL072's and the 7660s's. I believe i found a known good TL072 but every single 7660s either blew out immediately, got hot or just produced a quiet distorted sound.

As per a suggestion in another thread about the 27v boost, i attempted a jumper between 3 and 5 with one of the 7660s's that didn't blow out or get hot. Seemed to work well as a boost then, although treble knob would turn the volume up and all the way down rather than changing the treble (may be my treble capacitor the solder job is kind of weak i noticed the yesterday).

I took voltages of both chips with pedal on and the 7660s removed, as follows:

TL072
1 - 7.6 volts 8 - 8.6 volts
2 - 7.3 volts 7 - 7.6 volts
3 - 6.1 volts 6 - 7.6 volts
4 - 7.37 volts 5 - 7.6 volts

7660s sockets
1 - 9.4 volts 8 - 4.4 volts
2 - descending 7 - .01 volts
3 - 0 volts 6 - .003 volts
4 - descending 5 - 7.39 volts

I will attach pictures shortly if my phone lets me log in. Was having issues with that yesterday. Let me know if theres anywhere else i should take voltages. Thanks!

EDIT: i had the pins labeled wrong lol

The 7660s was a problem getting out so the holes are kind of rough. The TL072 is NOT currently soldered but seems to be making good contact since it worked when i had the jumper in.

Backside of board

FYI: I split these posts off from the other "27v boost kit" thread because we prefer to keep each problem in its own thread even when the symptoms seem the same.

OP, please let us know your precise symptoms, because the context of the other builder's thread is no longer in the thread with your photos.

_________________
Scott

My band, Austin Hollow

No problem sorry about that.

Symptoms: bypass works fine. When engaged the LED lights but sound is very faint and can only be heard if strumming very hard. Distorted sounding as well. Depending on which 7660s was installed there were varying degrees of awful noise and static as well.

Some of the 7660s’s i tried would smoke immediately, some would get hot and produce a burning smell, and others didn’t seem to get hot but would still be very quiet and distorted. The pedal seemed to work best when jumping pins 3 and 5 on one of the less offensive 7660s’s

Your voltage readings are way off. But I'm not sure what you've got going on in terms of what chips are in their sockets and what chips are out.

Please post your voltage readings, and describe what chips are in place.

If one of the chips are getting hot, don't bother posting those voltages. That chip is obviously not good, so don't waste your time with it.

Also, what power supply are you using? Make and model please.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

The readings in the first post are with the TL072 installed and the 7660s removed. Sorry if that wasn’t clear. I can take them a different way tonight if you need me to.

Using a truetone 1spot 9v powe supply. No daisy chain, straight into the pedal.

The 1Spot is the first problem. They cause all sorts of noise issues, especially with pedals that use charge pumps. It will work for taking voltage readings, but you should get another power supply. The cheapest power supply I would recommend is the BOSS PSA 120s.

As for your voltage readings, they don't help. If you are indeed getting a positive voltage on pin 4 of the op amp when there is no charge pump present, you have a serious short somewhere.

Remove C10 (the 10uF capacitor below the text that says 27v Boost), and take voltage readings again without the charge pump installed.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Double checked and those readings were correct. Removed the 10uf capacitor and rechecked voltage on the TL072 with no charge pump installed.

New readings:

1 - 8.16
2 - 7.84
3 - 7.68
4 - 7.85
5 - 8.16
6 - 8.16
7 - 8.16
8 - 8.77

Test for continuity between the + and - eyelets where the DC adapter jack connects to the PCB

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Pedal unplugged its about 20kohms

Plugged in and powered up is in the 16 megaohm range

I guess we have to assume that you have an internal short in your op amp. Please remove the op amp and take voltages of the empty solder pads/eyelets. Just to verify, the op amp, charge pump, and C10 should all be removed from the PCB.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

With both chips and C10 removed, voltage at the sockets for the TL072:

1 - 1.8
2 - 1.8
3 - 3.5
4 - .001
5 - 1.8
6 - 1.8
7 - 1.8
8 - 8.9

Some of these seem to be slowly descending, mostly the 1.8’s

So your old TL072 was definitely bad. Do you have a new TL072 handy? You should replace the TL072 and put a jumper between the two C10 eyelets. This will connect pin 4 directly to ground and give you a "9V" boost. So it should do everything you'd expect, it just won't have quite as much headroom.

Actually....you should just email sales@buildyourownclone.com and we'll send you a new tested op amp, charge pump, and 10uF, since it sounds like the replacements you ordered might be questionable.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

I will do just that. I had a feeling the chips were the issue. I did ground the op amp previously (though not at the C10 location. i think i just jumped the charge pumps ground to the op amp) and it seemed to work so i assumed it was ok. Crazy that so many of these chips are bad but i guess its a result of covid and trying to catch up on production.

Thank you very much for your help! I’ll post results when the new ones arrive.