Help fixing a TS10

daveanderson · October 06, 2013, 03:29:55 AM

Hi,

I am having some issues with an Ibanez TS10. The effect passes no sound when either bypassed or engaged. LED lights up as it should.

With a lead plugged into the input I get the following voltages at IC 1 are roughly

Pin 1: 4.5v
Pin 2: 4.5v
Pin 3: 4.5v
Pin 4: 0v
Pin 5: 4.5v
Pin 6 4.5v
Pin 7: 4.5v
Pin 8: 9v

But, without a lead plugged into the input jack I get:

Pin 1: 9v
Pin 2: 9v
Pin 3: 9v
Pin 4: 9v
Pin 5: 0v
Pin 6 9v
Pin 7: 9v
Pin 8: 9v

I have been using this schematic for reference
http://www.freeinfosociety.com/electronics/schemview.php?id=1086

I suspect the voltages without the lead have fried the IC, before I put a new one in I there anything in particular I should be looking at as a cause for these differing voltages?

Any help is much appreciated.

Kipper4 · October 06, 2013, 05:04:55 AM

Strange!!!!!!
you should (if im right) get the same voltages on the ic if the guitar lead is plugged in or not.
I would expect the kind of voltages you had with the lead plugged in (ie most 4.5v except 8=9v, 4=0v gnd) roughly.
Have you checked your Vref.
Probably best you do a full debugg thread.
Go to the "debugging what to do if it wont work"thread and post some more details please

duck_arse · October 06, 2013, 10:43:40 AM

those voltages suggest a fritzed ic. it seems like Vref is ok, though. any idea what may have caused the change in state, ie operating to non-operating?

slacker · October 06, 2013, 12:52:03 PM

Is this with a battery and are you measuring from the negative battery terminal? If you are then you will measure 9 volts from any of the IC pins, this is nothing to worry about and won't be the problem.
When there is no plug in the input jack the negative of the battery is disconnected from the rest of the circuit, you can see this on the schematic, the negative of the battery goes to the ring connection of the input jack, which doesn't go anywhere. When you plug a lead in the ring and sleeve connections on the jack are connected through the plug, connecting the negative of the battery to ground allowing it to power the circuit. This set up prevents the battery going flat when you're not using the pedal.
With no plug inserted when you try and measure the voltage the only path any current can flow through is through your meter, this only allows a very small amount of current to flow so you will measure about 9 Volts on all the pins.
The IC is not in the bypassed signal path so if it was bad and nothing else was wrong that wouldn't stop the bypassed signal. The bypassed signal goes through Q1, Q6, Q7 and Q2.
I would make an audio probe http://www.diystompboxes.com/wiki/index.php?title=Debugging and trace the signal through from the input jack to see if you can find where it stops, that might help give an idea what the problem is.

daveanderson · October 06, 2013, 11:10:58 PM

Thanks guys for the help, this I my first pedal repair so apologies if I am missing anything basic.

I had been measuring from the negative battery terminal, so that explains my IC readings.

I'm not sure what the cause of the failure was the pedal was DOA when I got it, I had assumed it was from a wrong power supply being used. So I had replaced D1 and all electrolytic caps.

I have just made an audio probe and lose signal after C1 so replacing that will be my next step, thanks again.

Edit: The pedal is now passing audio when engaged, clean no effect though. No audio is passed when the effect is bypassed.

GibsonGM · October 07, 2013, 07:59:37 AM

Do you get any signal at pin 3 of the opamp? How about pin 1? If not, how about at the emitters of Q1 and Q6?

If not passing audio in bypass, then suspect Q1, 6, 7 and 2, as Slacker posted above - the rest is not involved during bypass. I am curious what the voltages are at the notes that are labeled on your schematic (are they 9v, 4.5v, etc?).

Don't see why C1 would've been bad except that maybe someone applied WAY more voltage than they should have (wrong adapter?)...that little resistor network after C1 should be checked right off...

daveanderson · October 08, 2013, 12:43:09 AM

No signal at the op-amp or at the emitter of Q1. Does this indicate Q1 needs a replacement?

These are my measured voltages a the transistors.

Battery Voltage: 8.7v
Effect engaged.

Q1

C 7.87
B 8.56
E 7.84

Q2

C 3.61
B 8.54
E 3.61

Q3

C 1.39
B 0.80
E 0.76

Q4

C 0.29
B 7.02
E 0.79

Q5

C 1.38
B 0.85
E 0.75

Q6

C 7.08
B 8.42
E 7.41

Q7

C 3.96
B 0.02
E 4.05

Q8

C 3.93
B 0.01
E 4.03

Effect Bypassed

Q1

C 7.83
B 8.36
E 7.62

Q2

C 3.52
B 8.34
E 3.08

Q3

C 1.39
B 0.83
E 0.76

Q4

C 1.22
B 0.62
E 0.60

Q5

C 0.57
B 5.03
E 0.60

Q6

C 7.08
B 8.42
E 7.54

Q7

C 3.96
B 0.02
E 4.05

Q8

C 3.97
B 0.03
E 3.96

GibsonGM · October 08, 2013, 08:12:15 AM

Something is pretty off, but we'll figure it out, no worries.

I think the pinout you're using could be wrong. That 8.5v suggests to me that pin is the collector. Could be wrong, but maybe you should revisit that, be sure of which pin we're calling "C, B and E"? Anyway, there's a bias voltage missing to Q1...

You should have about 4.5V on the base of Q1. I'm not seeing that in your measurements, so that's worrisome. Next, we look at the voltage divider just below it...at the junction of R2, R3 and R4, you should read something like 6 to 6.5 volts. And supply voltage where it reads "+9V".

Do you?

After establishing that I am SURE which pins are which to Q1, if I didn't get good bias voltage at the voltage divider under Q1 I'd next lift R4 where it hits R1, isolating the divider, and would check again for bias. If it's good, then I'd change Q1. If it's bad, then I'd think a resistor is toast there, or that cap needs changing (likely suspect, electrolytics go bad). Right now, your job is to probe around and get some readings there, and make sure you have the right pinout....

daveanderson · October 09, 2013, 03:41:34 AM

Cool, I had the collector and base switched, these are now the correct pinouts.

I do get a voltage of 6v at the junction of R2, R3 and R4, and a supply of 9v on the left of r2.

On lifting the leg of R4 I get a reading of 5.5volts. This points to Q1 needing replacement, yeah?

I'll order some SC1815's. Thanks again for your help, really appreciate it!

Battery Voltage: 8.7v
Effect engaged.

Q1

C 8.56
B 7.87
E 7.84

Q2

C 8.54
B 3.61
E 3.61

Q3

C 0.80
B 1.39
E 0.76

Q4

C 7.02
B 0.29
E 0.79

Q5

C 0.85
B 1.38
E 0.75

Q6

C 8.42
B 7.08
E 7.41

Q7

D 3.96
G 0.02
S 4.05

Q8

D 3.93
G 0.01
S 4.03

Effect Bypassed

Q1

C 7.83
B 8.36
E 7.62

Q2

C 8.34
B 3.52
E 3.08

Q3

C 0.83
B 1.39
E 0.76

Q4

C 0.62
B 1.22
E 0.60

Q5

C 5.03
B 0.57
E 0.60

Q6

C 8.42
B 7.08
E 7.54

Q7

D 0.02
G 3.96
S 4.05

Q8

D 0.03
G 3.97
S 3.96

[/quote]

Renegadrian · October 11, 2014, 01:12:50 PM

hijack this thread to keep forum clean...

got a non working ts10, no sound at all and no led on off
just touching q3 collector (center pin), with one the other two or another point, turns the effect and the led on, so IC is good...guess I have some problem on the switching part?! audio probed, signal stops at q1 base - tried another transistor at q1 a bc182l (bce) without changes.

some readings with effect on

IC
1 3.83
2 3.83
3 3.82
4 0
5 3.77
6 3.99
7 3.83
8 7.75

q1
B 3.34
C 7.67 middle pin
E 4.33

q2
B 2.35
C 7.67
E 2.89

q3
B 1.35
C 0.78
E 0.73

q4
B 0.73
C 6.33
E 0.73

q5
B 1.33
C 0.81
E 0.73

q6
B 4.31
C 7.64
E 7.64

any hint?! THX guys!!!

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Help fixing a TS10