HELP GGG ITS8 No Sound When Turned On

[96ecss]

Hi,

I just built an ITS8 TS808 clone from General Guitar Gadgets. Here is a link to the project: http://generalguitargadgets.com/index.php?option=content&task=view&id=90&Itemid=118. I built it with only 1 modification, the AMZ Fat Mod.
There is no sound when I turn the pedal on. The bypassed sound is fine but when I turn the pedal on the LED comes on but there is no sound. I thought I had wired it wrong but I went back and checked all the wires and all the components on the board and everything seems to be in the right place. I checked the function of the 3PDT switch and I believe it is working properly.
The IC is a JRC4558D and the transistors are 2N3904. With the pedal turned on, I checked voltages at the battery, IC and both transistors and here is what I found:

Battery 8.80

IC:
1: 4.30
2: 4.30
3: 4.30
4: 0.00
5: 4.30
6: 4.30
7: 4.30
8: 8.80

Q1:
C: 8.70
B: 3.33
E: 2.70*

Q2:
C: 8.70
B: 3.33
E: 2.80

According to the project page on GGG, all the voltages are correct except for the Emitter on Q1. It should read 0.00. I checked closely for any solder bridges on the PCB but I didn't find any. The IC and both Transistors are socketed. Just to be sure, I replaced the socket and transistor at Q1 but it didn't make a difference.

What could cause that problem at Q1? Could that cause the pedal not to work? I really appreciate any help you guys can offer me. If there is any other info I should include, please let me know. Thanks in advance for the help.

Dave

[R.G.]

The information on Q1's emitter voltage at GGG is incorrect. It should actually not be 0V, but should be 0.4 to 0.6V less than the base, or about 2.8V. 2.70 is a little low, but nothing to write home about.

If it were mine, I'd recheck the pinouts and orientation of the opamp and transistors where they're plugged into the board. If that is absolutely, positively 100% correct, I would suspect solder joints and start using my ohmmeter to check for continuity between part leads which should be connected by traces, so you check whether the solder joints are making contact or not.

Yell if that does not help.

[Pushtone]

I read your post and since I had just finished the same project I took 15min to open 'er up.
I didn't read the instruction till tonight so I didn't know about the voltage chart on pg 3.
Mine has been sounding just fine.

After I made note of voltages on mine I started to wonder if JD didn't get Q1 and Q2 mixed up on that chart.

Then I come back and R.G. has confirmed my suspicion.
I don't think the voltages around the transistors is your problem.
Try probing in from the input with an audio probe connected to an amp. Fine where the signal ends.

Here is what my ITS8 is reading...


Supply: 8.8 vdc
IC:
1: 4.42
2: 4.55
3: 4.33
4: 0.00
5: 4.41
6: 4.42
7: 4.42
8: 8.80

Q1:
C: 8.88
B: 2.74
E: 3.43

Q2:
C: 8.88
B: 2.74
E: 3.42

See...? My reading for Q1 is like what JD has in the chart for Q2 and vis versa. 

I also did the Keely substitutions.


One curious thing...
The first power up I had one 3904 and one 5088 and got lots of hiss.
Put in two 5088 and hiss went away. Did not try two 3904s.

Good luck

[96ecss]

R.G. and Pushtone, thanks so much for the help. The voltage thing was throwing me off. I checked around with an audio probe and found capacitor C10 had 1 lead in the wrong place. Re-soldered it and problem solved.

Pushtone, how do you like the Keeley mods? Did you do them at the time you built the pedal or after? I'm wondering how much it changed the sound. I did Keeley's mods to a Boss BD-2 I have and I like it better than stock.

My wife and son are in bed. I can't wait until morning so I can crank it up and really hear it.

Thanks again,

Dave

[Pushtone]

Great, congrats.

Pushtone, how do you like the Keeley mods? Did you do them at the time you built the pedal or after? I'm wondering how much it changed the sound. I did Keeley's mods to a Boss BD-2 I have and I like it better than stock.

I just went with them so I can not compare.
It does kinda work like the Keely description says, but hard to tell.
http://www.robertkeeley.com/product.php?id=31

My BSIAB can rock harder, but not as sweet as the 808.
I did socket the output cap and have tried keely's and the stock value with no noticeable difference.


I was wondering if the AMZ fat mod and the Keely mods over lap.
I mean, will the Keely mods make the AMZ fat mod moot?
Thats what it sounded like after reading the GGG mod sheet and the Keely mod description

I guess I'll have to try it to find out. After I jam through it for a week 

[96ecss]

Great, congrats.

Pushtone, how do you like the Keeley mods? Did you do them at the time you built the pedal or after? I'm wondering how much it changed the sound. I did Keeley's mods to a Boss BD-2 I have and I like it better than stock.

I just went with them so I can not compare.
It does kinda work like the Keely description says, but hard to tell.
http://www.robertkeeley.com/product.php?id=31

My BSIAB can rock harder, but not as sweet as the 808.
I did socket the output cap and have tried keely's and the stock value with no noticeable difference.


I was wondering if the AMZ fat mod and the Keely mods over lap.
I mean, will the Keely mods make the AMZ fat mod moot?
Thats what it sounded like after reading the GGG mod sheet and the Keely mod description

I guess I'll have to try it to find out. After I jam through it for a week 

The Fat mod is definitely noticeable, even at very low volume. I'm interested in the increased gain in the Keeley mods. I love my BSIAB2 too.

Dave

[Cliff Schecht]

Go read my thread on this, I think the information you guys are looking for is there .