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Sunking Ic2 Overheating and Bypass signal low.

Started by rawkcraze, January 10, 2012, 11:13:30 PM

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rawkcraze

so i just recently build the Sunking V3 with the buffer instead of truebypass and im already in love with the tone. makes everything sound really big and full.
but im finding that Ic 2 is getting really warm. i havent blown a chip yet, but i dont want to have it happen in the middle of a show. also, my bypass signal is alot lower then my when i plug my guitar straight into the amp. what could be causing ether of these?

heres the V's im getting

Voltage in: 9.51v

Ic1:
1-4.76
2-4.76
3-3.8
4-0
5-4.79
6-4.67
7-4.67
8-9.51

Ic2:
1-4.74
2-4.79
3-4.8
4- -4.06
5-4.8
6-4.8
7-4.84
8-12.94

Ic3:
1-9.51
2-5.09
3-0
4- -2.04
5- -4.05
6-4.88
7-6.19
8-9.51

i know that pins 4 and 8 are off by half of what they should be on IC2, and that so are 4 and 5 of IC3.
the orientation of C19 between Ic1 pin 4 and Ic3 pin5 has the correct orientation. but whats making it half the negative voltage it should be?

what also could be wrong with the bypass buffer? when i turn the volume up in bypass on the pedal it turns the overall volume up, but then when i engage the pedal its too loud.

using tc1044scpa, tl072cp's and BAT41 for the clipping diodes.

also, any tips on getting it in a 1590b with a battery?

madbean

First, are you getting 18v out of the charge pump portion of the circuit? Try removing IC2 and IC1 and then measure pin8 of IC2. Does it read ~18v?

Also, double check to make sure you have used two 27k resistors for the voltage divider that creates the Vb supply rail. It should measure about 4.5v.

rawkcraze

yeah im getting 18.2 volts on pin8 of ic2. without the ic 1 and 2 in.

are you talking about r29 and r30? yes they're both Red,Violet,Orange, Gold (27k's)
(R17's 27k too, but i dont think thats the one youre talking about.)
and yeah im getting 4.76V on the supply rail. kinda strange isnt it?
it sounds amazing when its on. maybe ill just leave it on all the time.

edit: found a bad connection on C2. lemme go solder it back on and see if that helps

rawkcraze

#3
okay so now the bypass works great, and when i turn it on it sounds great. but there's kind of a high pitch whine sometimes? it sounds like a tv's turned on (without a show on). if that makes sence. im guessing thats the tc1044scpa?

also, ic2 isnt getting hot, but now IC3 is. maybe it was ic3 that was getting hot this whole time. any more things i should check?

oh no.. im missing C14.. but it still works? isnt that just a capacitor to control the bass/highs? or would that be whats causing this?

rawkcraze

yep.. IC3 just blew :/ better order another one..

whats the best substitute if i cant get an icl7660scpa?
i can get an icl7660cpa, and a whole lot of other ones without the S.
or the Max1044scpa or just another tc1044scpa?

madbean

I've never had an issue with faulty TC1044s, so I think it's safe to just use that. It's normal for it to get warm, but not excessively.

rawkcraze

#6
okay cool. i happened to order a 2nd tc1044 so we'll see if that fixes it.
how warm is "warm"? cause maybe i was freaking out about nothing

edit: no it gets burning hot the second i plug it in..  :-\ do you have any other suggestions?