Klon Woes

[ac30irons]

Hey all, so I have done a Klon board minus the charge pump. Used a pretty standard schematic. Just knocked one up and am getting zero sound at pin 1 of ic2, before all is fine. I have checked, checked and double checked all components etc, reflowed too - I am perplexed. Something tells me maybe I have something wrong on the schematic in loo of removing the CP and associated components, likely in the power section

IC2 Voltages

1 - 9.25
2 - 4.9
3 - 9.3
4 - 0
5 - 9.3
6 - 9.14
7 - 9.28
8 - 9.3


Any help would be really appreciated.

 

[jimilee]

https://www.freestompboxes.org/viewtopic.php?t=31222

Here’s a link to the one in FSB. I verified it. Have a look.

 

[ac30irons]

https://www.freestompboxes.org/viewtopic.php?t=31222

Here’s a link to the one in FSB. I verified it. Have a look.

Thanks for digging that out man - looking at the schematic if I start with changing teh resistors in the power section to 10k and the resistor between pin 1 and 2 of Ic2a too 100k !!!

 

[bean]

Something is wrong with VB bias voltage. Check the values of R29 and R30. Measure the voltage on the + end of C30. It should be around 4.5v.

 

[z2amiller]

I think pin 3 and 5 of IC2 should be tied to VREF (Vb) and not 9V. (9V maybe a holdover from using a charge pump where it was halfway between 18v and gnd?)

 

[bean]

I think pin 3 and 5 of IC2 should be tied to VREF (Vb) and not 9V. (9V maybe a holdover from using a charge pump where it was halfway between 18v and gnd?)

Good catch. That's it. I missed the pin names.

 

[ac30irons]

Something is wrong with VB bias voltage. Check the values of R29 and R30. Measure the voltage on the + end of C30. It should be around 4.5v.

Thanks man, also thanks for your awesome Eagle package - it’s helping learn layouts sooo much, bloody legend.

 

[ac30irons]

I think pin 3 and 5 of IC2 should be tied to VREF (Vb) and not 9V. (9V maybe a holdover from using a charge pump where it was halfway between 18v and gnd?)

Ahhhhhhhh feck, thanks dude - now to hack the pcb

 

[z2amiller]

Ahhhhhhhh feck, thanks dude - now to hack the pcb

Worst case you can probably just bend those pins out from the socket (cuz you used sockets right?) and bodge it to VREF somewhere.

If you did SMD or soldered right to the board it'll be a little harder, but should be at least hackable without getting new PCBs made.

 

[ac30irons]

Worst case you can probably just bend those pins out from the socket (cuz you used sockets right?) and bodge it to VREF somewhere.

If you did SMD or soldered right to the board it'll be a little harder, but should be at least hackable without getting new PCBs made.

Thankfully I always socket ICs. Popped 3 and 5 out and bridged them. The Ic is right under the gain pot so it a short hop to Vref. Not has chance to test but will report back tomorrow.
Thanks again brother.