Dear Kluber,
It seems that only noise is working on low tom. You have to check the oscillator.
Measure with a scope the signal you get when Lowtom is trigged at IC15 Pin7, Pin1.
Post result here.
Best regards,
e-licktronic
Low Tom Issue [SOLVED]
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e-licktronic Site Admin - Posts 519
- Joined: Feb 16th, '11, 13:36
Best regards,
e-licktronic -
Hey Vincent,
I tried to measure with the scope pin 1 and 7 and the signal is too weak to get any result. What would be the measurements you if it's everything normal?
I bought a new IC 4558C and nothing changes.
I resoldered all the pins on the LowTom section.
No luck so far.
BUT the low tom came back for a short time twice when I plugged the PSU... Not sure what's going on here
I tried to measure with the scope pin 1 and 7 and the signal is too weak to get any result. What would be the measurements you if it's everything normal?
I bought a new IC 4558C and nothing changes.
I resoldered all the pins on the LowTom section.
No luck so far.
BUT the low tom came back for a short time twice when I plugged the PSU... Not sure what's going on here
OK, I finished the electrical part of my build this afternoon and fired the Yocto up for the first time. 
I was initially listening to each of the sounds to see how much adjustment I had to do and to my relief most are spot on. Handclap needs a few subtle tweaks but all well and good… until the High Tom dropped out just like Kluber’s.
The High Tom was sounding great, then it became just a huff with no body to the sound.
The Yocto was physically static so no wires can have moved. I was just turning individual level pots up and soloing each instrument. The High Conga sounds a bit quiet now too.
I was initially listening to each of the sounds to see how much adjustment I had to do and to my relief most are spot on. Handclap needs a few subtle tweaks but all well and good… until the High Tom dropped out just like Kluber’s.
The High Tom was sounding great, then it became just a huff with no body to the sound.
The Yocto was physically static so no wires can have moved. I was just turning individual level pots up and soloing each instrument. The High Conga sounds a bit quiet now too.
LFO2VCO 
Did you manage to have a listen to my soundcloud link?
Do you have exactly the same issue?
Did you try to measure with your oscilloscope what Vincent did suggested?
I didn't get the measures however I've changed the IC but no luck...
If I could understand the theory on the Tom section it would be easier though.
Maybe we should test the diode...
Wow how strange I have just replug the PSU today and the LowTom works just like it should...
It seems there is a bad solder somewhere on the PCB
Did you manage to have a listen to my soundcloud link?
Do you have exactly the same issue?
Did you try to measure with your oscilloscope what Vincent did suggested?
I didn't get the measures however I've changed the IC but no luck...
If I could understand the theory on the Tom section it would be easier though.
Maybe we should test the diode...
Wow how strange I have just replug the PSU today and the LowTom works just like it should...
It seems there is a bad solder somewhere on the PCB
Hey Kluber,
It was quite late when I got the rascal up and running, so I decided to leave tests until I have a bit of spare time.
I’ll check Vincent’s suggestions for sure… I’ll also try to decipher which resistors and capacitors make up the + – power supplies for the High Tom. I doubt that the IC is to blame as the noise component is still audible. I was also wondering about the transistors or as you suggest diodes.
Odd that we have similar (on the face of it) issues.
It was quite late when I got the rascal up and running, so I decided to leave tests until I have a bit of spare time.
I’ll check Vincent’s suggestions for sure… I’ll also try to decipher which resistors and capacitors make up the + – power supplies for the High Tom. I doubt that the IC is to blame as the noise component is still audible. I was also wondering about the transistors or as you suggest diodes.
Odd that we have similar (on the face of it) issues.
Well, as I said the Low Tom works fine so far without touching anything since 2 days... And I had resoldered back then all the pins of this section...
So I'm guessing there should be some bad soldering here and there, don't you think?
I was going to buy some germanium diodes, and a couple of transistors, but I don't need too...
So I'm guessing there should be some bad soldering here and there, don't you think?
I was going to buy some germanium diodes, and a couple of transistors, but I don't need too...
I don't get what you mean...?lfo2vco wrote:I’ll also try to decipher which resistors and capacitors make up the + – power supplies for the High Tom.
I’ll keep my fingers crossed that my Tom wanders back too 
Glad your Yocto is fully functional now.
What do I mean… each instrument has it’s own branch from the positive and minus power supply. These spur off from the pads on the main board +15, +5, –15 and ground and run along the top edge of the board as a row of 21 capacitors and resistors (I think). I have had flu for the last week so I could just be delusional… 
Glad your Yocto is fully functional now.What do I mean… each instrument has it’s own branch from the positive and minus power supply. These spur off from the pads on the main board +15, +5, –15 and ground and run along the top edge of the board as a row of 21 capacitors and resistors (I think). I have had flu for the last week so I could just be delusional…
Alright get it! 
You might check minus/plus pads then.
If you weren't touching the PCB when the High Tom went faulty, then I'm guessing there is something with a faulty solder.
I doubt a component died/burnt just like that!
You might check minus/plus pads then.
If you weren't touching the PCB when the High Tom went faulty, then I'm guessing there is something with a faulty solder.
I doubt a component died/burnt just like that!
High Toms are back, I went over the circuit with a hot iron. Must have bee a faulty joint.
Hurray!
Happy for you!
Happy for you!