# Triangulum silent when engaged



## derbstens (Oct 27, 2019)

Hi everyone,
I am new to the forum an electronics itself. I finished building the Triangulum boost yesterday and I must have done something wrong or there is a faulty component somewhere in the circuit.
Basic things like checking solder points or looking for shorts I have already done.
let me describethe problem a little more detailed:
when bypassing, led goes off and the signal is passed thru as it should.
when engaging , the led comes on and only a inaudible signal is present on the audiointerface. When turning the pot clockwise, the signal increases but stays in an inaudible level.
I measured some values on the transistors and the ICs. All diodes are oriented as recommended.

I measured some values hat I drew into the photo, maybe that is of some use.

does anyone have a clue, what to do next?
Thanks for any help.


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## zgrav (Oct 27, 2019)

I suggest posting a picture of the other side of your PCB.


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## derbstens (Oct 27, 2019)

Ok:


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## ErickPulido (Oct 27, 2019)

I had two issues with this build, the first one bas solder on the 4u7 cap in thr sound path hence no sound when engaged, then a big squeal due to a loose contact between the tl071 and the  ic socket, had to solder it and problem solved, hope this helps


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## derbstens (Oct 27, 2019)

I just re soldered everything for the third time. No avail.
I now ordered the more complex parts again and see if swapping them one by one solves the problem.
Until this stuff arrives, i call it a day.


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## Robert (Oct 27, 2019)

derbstens said:


> I just re soldered everything for the third time. No avail.



Check R103, it's supposed to be 820K but in your pic it looks like 820 ohm.

Also R18 looks like it's 820K and should be 820 ohm....  I believe you got those two mixed up.


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## derbstens (Oct 27, 2019)

Thanks!
I‘m sure this will do the job! Unfortunately i‘ll be at the workshop only next weekend. I‘ll keep you posted.


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## Chuck D. Bones (Oct 28, 2019)

That should not have damaged anything.  Swap / replace those 2 resistors and you're good to go.  Be careful to not damage the board when you desolder the two resistors.  You'll need a solder sucker or solder braid & flux to desolder them.  If you have spare parts, cut the resistors out, then desolder the leads one at a time.  You've already heated the pads 3 times, they won't take much more of that before they start lifting off the board.

Note: zero volts on all 3 leads of Q2 is normal because it doesn't do anything.


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