Boss GE-7 Repair

[audiobalm]

Hi All,

I hope it's ok to ask this question in this forum. I've found it really helpful when building my own stomp box, and now need some advice troubleshooting a boss pedal.

My Boss GE-7 recently decided to stop working. It works bypassed, i.e. normal signal goes through, however when the pedal is activated I only get a low rumble. The LED lights, and the sliders increase or decrease rumble frequencies, but guitar tone is completely absent.

I've opened it up, and all connections appear to be ok. I've taken measurements using a 9.6v adaptor. There's a lot here. Everything looks somewhat normal, though I don't really know what normal is supposed to look like. Q2 and Q3 appear a bit low, but honestly I don't know what they should be! And for the life of me, I can't find Q1 anywhere even though it's listed on the schematic.

Anyway, any help on how to proceed in terms of troubleshooting or if you spot something that's untoward would be greatly appreciated. I could take this to my local repair person, however I'd like to see if I can solve the issue myself.

many thanks!

David


Q1

Cannot Find!

Q2

E - 0
C - 0.05
B - 0.65

Q3

E - 0
C - 0.02
B - 0.62

Q4

S - 5.7
G - 0
D - 3.25

Q5

S - 3.25
G - 0
D - 3.25

IC1

1 - 4.91
2 - 4.91
3 - 4.5
4 - 0
5 - 4.5
6 - 4.9
7 - 4.9
8 - 9.8

IC2

11 - 4.91
2 - 4.91
3 - 4.5
4 - 0
5 - 4.5
6 - 4.9
7 - 4.9
8 - 9.8

IC3

1 - 4.91
2 - 4.91
3 - 4.5
4 - 0
5 - 4.5
6 - 4.9
7 - 4.9
8 - 9.8

IC4

1 - 4.9
2 - 4.9
3 - 3.25
4 - 1.92
5 - 2.56
6 - 0.14
7 - 8.85
8 - 9.8

IC3 II

1 - 8.7
2 - 8.1
3 - 8.09
4 - 0
5 - 2.46
6 - 4.94
7 - 4.94
8 - 9.8

[ElectricDruid]

IC4 looks suspicious, if it's a standard dual package (I notice there's one SIP on there). Pin four isn't at ground. Other pins are wayward too.

IC1,2, and 3 all look fine.

IC3 PtII would be my guess for the SIP. Is that right?

[audiobalm]

Ic3 pt II is labelled thusly because there seems to be two ICs labelled IC3.

It's the long thin one to the bottom left of the picture.

I'll retake the measurements in IC4 Just to make sure I've got them correct. Everything is so close it's hard to measure.

[antonis]

Q1
Cannot Find!

It's 3 items closer to OUTPUT tip..

https://www.hobby-hour.com/electronics/s/ge7-equalizer.php