Ok, I was hoping never to have to do this, but here we are… my first troubleshooting thread… I think ![Big grin :D :D](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
I built a combo; Frost Drive in a Raincoat.
RainCoat seems OK. But the frost drive for a TS, doesn’t do what I would expect. And there‘s a few this that are just odd.
Here’s the list of odd behaviour:
- Tone knob goes from muddy to super bright in the last 1/20th clockwise.
- Level and Drive maxed out does induce much clipping, it more like just a boost
- Freq and Impedance trimmer doesn’t affect the sound at all
- Mid doesn’t seems to change the tone at all, I used a C100K Dual and applied the recommended changes to R4-5 and C3-4.
- Hi-Cut and Lo-Cut seems to work in different direction. Ex: Lo-Cut gets bright when going CW and Hi-Cut get dark going CCW. I used C10K from the same batch, so it’s not like one is a reverse pot.
- Dip switch seems to have no impact.
Troubleshooting performed so far:
Check the voltage at the MPSA18 +9V is coming in, and check the voltage at R14, -9V is there, so I concluded the charge pump is working fine.
Swap the MPSA18, no impact.
Swap both 4558 and the 1044, no impact.
So at this point’ I’m looking for pointers… In my list of options:
- Reflow the C100K Dual as the mid seems not to work. But inspection let me think it’s fine.
- Replace the C10K of the Tone, maybe it’s defective hence all the bright just at the end (I should measure it resistance to see if it’s just jumping at the end.
I’m attaching picture of the board before assembly, maybe you could spot a mistake.
Thanks in advance….
I built a combo; Frost Drive in a Raincoat.
RainCoat seems OK. But the frost drive for a TS, doesn’t do what I would expect. And there‘s a few this that are just odd.
Here’s the list of odd behaviour:
- Tone knob goes from muddy to super bright in the last 1/20th clockwise.
- Level and Drive maxed out does induce much clipping, it more like just a boost
- Freq and Impedance trimmer doesn’t affect the sound at all
- Mid doesn’t seems to change the tone at all, I used a C100K Dual and applied the recommended changes to R4-5 and C3-4.
- Hi-Cut and Lo-Cut seems to work in different direction. Ex: Lo-Cut gets bright when going CW and Hi-Cut get dark going CCW. I used C10K from the same batch, so it’s not like one is a reverse pot.
- Dip switch seems to have no impact.
Troubleshooting performed so far:
Check the voltage at the MPSA18 +9V is coming in, and check the voltage at R14, -9V is there, so I concluded the charge pump is working fine.
Swap the MPSA18, no impact.
Swap both 4558 and the 1044, no impact.
So at this point’ I’m looking for pointers… In my list of options:
- Reflow the C100K Dual as the mid seems not to work. But inspection let me think it’s fine.
- Replace the C10K of the Tone, maybe it’s defective hence all the bright just at the end (I should measure it resistance to see if it’s just jumping at the end.
I’m attaching picture of the board before assembly, maybe you could spot a mistake.
![DCF56413-E4BC-48A9-826C-7042D068D5C8.jpeg DCF56413-E4BC-48A9-826C-7042D068D5C8.jpeg](https://forum.pedalpcb.com/data/attachments/23/23852-74750033fd0c18c2fa0d2d5e973181d2.jpg)
Thanks in advance….