EHX Lumberjack

[Grrrg]

Hi, I got a broken unit. Some of te ICs get really hot and it sounds like something is not right. I know it sounds unusual per se but the getting hot and weird behaviour of the log pot (sound fades in and out while turning it) makes me think something is wrong. It is pretty packed so a schematic would be greatly appreciated.
Thanks
Grrrg

[Enzo]

ICs should not get hot. Are you sure the proper power supply is in use?

[Grrrg]

It is the ehx 9.6V Standard supply. The voltage is pulled down to 8.2 V which is not good. Resistance between + and - is 7 K (supply unplugged) which seems also low. But it is a double sided board and SMD so it is hard to follow the path and a schematic would be helpful.
I found nothing on the net, the pedal is quite new and not too popular. I also asked the support at ehx.

[Enzo]

Don't rely on the interweb, CALL EH and ask if they can support.

[g1]

Can you lift the power pins on any of the IC's that are getting hot?

[Grrrg]

It's all SMD so I'd rather not. And it is not only one that is getting hot.
I have to wait till next week to look at it at work, where we have a microscope and hot air for desoldering SMD stuff.
And maybe I will hear from EHX
Thanks so far

[Enzo]

If only one is getting hot, replace it, can you not identify it?

[Grrrg]

Not only one is getting hot. Actually after a short while the whole board gets hot. Even the pots. I am surprised it is still producing sound.

[Helmholtz]

. Resistance between + and - is 7 K (supply unplugged) which seems also low.

A 7k load would result in 1.3mA supply current. That's actually very low and can't explain the voltage drop and hot ICs.

Did you observe polarity while measuring resistance?

[Grrrg]

I didn't observe polarity but since there are diodes following the plug I thought the resistance measured with a multimeter should be higher, but I checked some other pedals and got very different numbers. One was also only 8k the others way higher like several 100 k.

[Helmholtz]

I didn't observe polarity but since there are diodes following the plug I thought the resistance measured with a multimeter should be higher, but I checked some other pedals and got very different numbers. One was also only 8k the others way higher like several 100 k.

I think the problem is that the meter's measuring voltage is too low and some semiconductors will not conduct below some threshold voltage.

You would have to measure current with the power supply connected.

[Grrrg]

So, finally I find the time. Under sufficient magnification I found the two ICs to be TC7660. With the help of the datasheet and looking at the traces I figured they are used as a charge pump. One resistor looked a little brownish and it led to the supply pin of the second TC7660 in the line. That pin's resistance to ground measured way lower than the other's. Ordered the IC. Exchanged it. Happy end!
Thanks to everyone involved except EHX support who didn't even bother to answer to my request.