Build Your Own Clone Message Board

Hi I have recently started building one of your analogue delay pedals which is not working at the moment. I've read the posts on this forum and managed to trace the signal using the probe to R7. The signal is present on the input of R7 but does not come out. I have reflowed the solder on that component and tested the resistor with a DMM and it reads 1.002K so appears to be functioning correctly apart from the fact my guitar doesn't get through.

Also IC1 seems to be getting very hot. Is this normal? I've been a bit paranoid about it so have been powering down the pedal after 5 mins of trouble shooting, letting it cool and then having another go.

Can anyone suggest what I should do next?

Any help would be much appreciated.

IC1 getting hot is definitely not normal. Check the value of R8. Make sure it's 470K ohms and not 470 ohms or similar lower value. What are the DC voltages on the pins of IC1?

Thanks for the quick feedback.

I have checked R8 and your right it is reading 19.77K so way off the 470 mark. Its banding is correct (yellow, purple, black, orange, brown) so does that mean its faulty? I've never met a faulty (new) component before so find it a bit hard to believe.

I haven't had chance to check voltages on IC1 yet as I've left the power supply at our rehersal rooms. When I do, do I check across pins ie DMM leads on pins 1+2 and take voltage then 3+4 and so on. Or do I put one lead of the DMM on the each pin and the other on the negative lead of the power input/output.

Thanks for the help.

If you measured R8 while it's still in the circuit you can through your measured value out the window. In a lot of cases you cannot get an accurate measurement of a resistor while it is still in the circuit. You end up measuring the resistor in parallel with the rest of the circuitry which will give you a false reading. The color code is correct so chances are the resistor isn't the problem.

To take voltage measurements you connect the black (ground) probe of your DMM to the chassis or sleeve of one of the pedal's jacks. With power connected and a plug in the input jack touch the red probe to each of the op-amp's pins. There should be no voltage on pin 4 since it is ground. You should have 9V on pin 8.

Alright, checked the voltages on IC 1 they are as follows.

pin 1 - 6.22
pin 2 - 4.75
pin 3 - 4.70
pin 4 - 0.01
pin 5 - 4.56
pin 6 - 5.64
pin 7 - 5.92
pin 8 - 8.92

The voltage going into the pedal is 8.94v

Also regarding your last post about measuring resistors out of the board, do you think I need to take R7 and R8 out and check them?

Thanks again for your help.

Several of your voltages are off by a volt or two. Here are the readings I got from mine.

1) 4.5
2) 4.5
3) 4.29
4) 0
5) 4.5
6) 4.5
7) 4.5
8) 9

I'd suggest that you post some pix of your build. Include shots of both sides of the PCB and shots of the wiring to the stomp switch and jacks. Make sure the pix are in focus, well lit and up close. We need to see details. Your pix should be as if we have the build right in front of us.

If the color codes for R7 (Brown-Black-Black-Brown-Brown) & R8 (Yellow-Violet-Black-Orange-Brown) are correct I wouldn't worry about them.

O.K here are a few shots, don't hold back if the build sucks then let me know.......

and the last one.

Many of your solder joints need to be re-done. I see several solder starved and/or cold solder joints. Since your resistors are mounted vertically it's impossible to tell if you have them in all the right places.

And after you re-do the soldering, wipe down the pcb with some isopropyl or rubbing alcohol to clean off the stray solder and flux residue.

Thanks guys, will redo the soldering. If you have time could you give me an example of a good joint I have done (if there is one) and a bad one so I know what they should look like once finished.

I did think it was odd to put the resistors in like that, but that's what it said in the instructions. I've built an OD2 and on that I put them in normally but I thought I better do it this way for this one as it seemed to be quite explicit in the instructions, should I desolder them and put them in the standard way?

Thanks again for all the help. This pedal has been quite an education to say the least!

Thanks again.

I know this is a pretty old post but just to pass on the solution to this little problem.....

In the end I didn't resolder I checked every joint with a DMM for continuity and found them to be o.k while I was doing this I noticed that I'd put the wrong chip in the IC1 socket, which is why the chip was getting hot and the delay line was not working. What a dumb mistake but there you go. Delay works fine now apart from one little niggle that I'll post separately if I can't find the answer on the forum.