Tyrian Distortion...

Cybercow

Member
R2 is NOT 10K Ω. It is a current limiter that should be 10 Ω. Un socket ALL of the ICs, replace R2 with the correct 10 Ω value resistor and check the voltage supply section to ensure VCC and VREF are OK. Let us know how that goes.

My guess is that the 10K Ω resistor smoked because it was trying to limit too much current and surpassed the wattage rating of the anticipated 10 Ω rating. If the 10K smoked, other components may have joined it in its leap into destruction. If replacing R2 with the designated 10 Ω resistor then provides proper VCC & VREF values at the measuring points indicated on the schematic, it may be safe to replace all the socketed devices.
 
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Mourguitars

Active member
That's my bad i meet 10R....i glanced at the build sheet , i scribbled it out with a pen, just seen the 10...again great catch!

Ill try a different batch of 10R's i have
 

Cybercow

Member
Did it smoke with all the socketed devices pulled? If so, you need to pull and test all the components in the supply section. Double check that C2 nor C4 have shorted. IC1 and IC2 may also be suspect as they are also directly connected to R2.
 

Cybercow

Member
It looks as though IC1 is soldered directly onto the PCB. And it and IC2 are in backwards according to your photos. They will likely need replacing. SOCKETS ! ! ! ! !
 

zgrav

Active member
You will see some discussion about the pros and cons of using sockets for ICs and transistors. Especially for people new to the hobby, I think sockets are essential. First, you may ruin a board trying to unsolder an IC that was soldered in place. Second, when something isn't working, it makes it much easier to test an IC or a transistor by trying another one.
 

Mourguitars

Active member
It looks as though IC1 is soldered directly onto the PCB. And it and IC2 are in backwards according to your photos. They will likely need replacing. SOCKETS ! ! ! ! !

I see ....i always thought the ( dot ) goes forward..

I can try to unsolder not much of the legs went thru so a wick or solder sucker it should come out, ...i did replace R2 ....C2...and C4
 

Chuck D. Bones

Well-known member
Save the board! Cut the IC leads, remove the IC and then unsolder the cut leads from the board one at a time. If the IC is blown (and in this case they are) then they're going into the trash anyway. Even a bare board is worth more than any of the ICs. A populated board is worth the board and every component on it, plus the time and effort to install them. If you're lucky, you didn't burn any traces. Visually inspect all of the traces leading to both sides of R2. Look for breaks, burn marks or blistering. Burnt traces can be repaired. Film resistors make good fuses.
 

Mourguitars

Active member
Desoldered and Swapped the Top IC....came out easy, soldered in the RIGHT WAY ! ..put the other in the RIGHT WAY !

Got LED ! ....whew

Now the sound test...great call on the IC's in backwards , went to the eye Dr and need Prizm glasses...

Need to change my name to Mr McGoo !...lol
 

zgrav

Active member
there is no real "forward" or "backward" when placing an IC on a board -- follow the build document.
 
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