Troubleshooting ts10
- Thread starter Einzeln
- Start date
i am using the TH audio probe in my first attempt to search a defect. I changed a burned diode and Capacitor at the power section.
With the probe I am loosing the signal at R23.
Is at as simpel as replacing that or am I missing something in understanding why I it is possible to loose signal at that point?
In bypass signal reaches output btw
Is it common practice to measure voltages before audiotracing?
With the probe I am loosing the signal at R23.
Is at as simpel as replacing that or am I missing something in understanding why I it is possible to loose signal at that point?
In bypass signal reaches output btw
Is it common practice to measure voltages before audiotracing?
Last edited:
thomasbe86
Well-known member
you should have 4.5v ish between R23 and R24. I think between R23 and C15 should be your bybassed signal (buffered bypass), so that is normal to not have a signal when engaged here, if this is working, problem is elsewhere. Do you have pictures of the board?
OK so far:
I think the power section is a little bit different from the schematic. C22 is 100uF on the board for example.
I think in the schematic the 2 opamps are other way round. I have the clipping diodes on 6 and 7 of the IC.
A lot of signal on the first opamp and after the non inverting side of the second signal is almost gone.
Safe to say one of the opamps has died?
Or is their another reason why the signal stops after the opamp? Signal on both gain and tone control. Voltages are around 8,95 and 5 volt
I think the power section is a little bit different from the schematic. C22 is 100uF on the board for example.
I think in the schematic the 2 opamps are other way round. I have the clipping diodes on 6 and 7 of the IC.
A lot of signal on the first opamp and after the non inverting side of the second signal is almost gone.
Safe to say one of the opamps has died?
Or is their another reason why the signal stops after the opamp? Signal on both gain and tone control. Voltages are around 8,95 and 5 volt
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Feral Feline
Well-known member
Why was D1 & C20 burned?
If there's a problem with the board/circuit, it will do no good to replace D1 & C20 to only have them burn up again, possibly taking out other components with them the 2nd/3rd/4th/etc time around.
Use your continuity setting to check for shorts in the power supply.
I'd also go through the board and retrace it while reading the schematic (and relabelling it as necessary).
[EDIT: Just looked at the schematic again and there's a lot of RefDes missing from it, so I'd definitely trace the entire pedal and fill in the blanks.]
Check the two 10k resistors that form the voltage-splitter to get the +4v5 — C20 is just after that voltage divider and would be feeding the OP-AMPs via various resistors, so I'd make sure the 10k/10k voltage divider is working. Of course, the full +9v is coming into the IC via pin 8, but I'm wondering if C20 is burnt out, what things down4v5stream are getting sizzled.
Hmmm there's nothing 4v5 hitting the 2nd op-amp — There's 9v feeding into pin5 via a 10k;
Pin3 is getting 4v5 via 10k while pin2 is getting 4v5 via 4k7/47n combo... I'd check those as well, make sure whatever damaged C20 isn't getting that far.
Moving forward I'd do two things:
Going through the circuit in its entirety may be tedious, but it may help you catch the problem or other problems and, at least for me, it's educational — a good exercise.
If there's a problem with the board/circuit, it will do no good to replace D1 & C20 to only have them burn up again, possibly taking out other components with them the 2nd/3rd/4th/etc time around.
Use your continuity setting to check for shorts in the power supply.
I'd also go through the board and retrace it while reading the schematic (and relabelling it as necessary).
[EDIT: Just looked at the schematic again and there's a lot of RefDes missing from it, so I'd definitely trace the entire pedal and fill in the blanks.]
Check the two 10k resistors that form the voltage-splitter to get the +4v5 — C20 is just after that voltage divider and would be feeding the OP-AMPs via various resistors, so I'd make sure the 10k/10k voltage divider is working. Of course, the full +9v is coming into the IC via pin 8, but I'm wondering if C20 is burnt out, what things down4v5stream are getting sizzled.
Hmmm there's nothing 4v5 hitting the 2nd op-amp — There's 9v feeding into pin5 via a 10k;
Pin3 is getting 4v5 via 10k while pin2 is getting 4v5 via 4k7/47n combo... I'd check those as well, make sure whatever damaged C20 isn't getting that far.
Moving forward I'd do two things:
1) Remove the IC and install a socket, install a known good fresh IC, but only after making sure there's no power shorts etc. No point in toasting ICs, whatever they cost.
2) Install a 1N5817 between the DC-jack and the board
Going through the circuit in its entirety may be tedious, but it may help you catch the problem or other problems and, at least for me, it's educational — a good exercise.
Not sure why it burned. Not my pedal. Wrong power supply is my guess. But I am not sure.
It is my first real attempt troubleshooting and it is gonna take some time. Thats ok.
I use the schematic and try to follow the traces.
I measure 8.95 volt and around 5,6 volt??? after the voltage divider
Have to take at look what I put at D1
C20 in the schematic is a 47u but on the board it was 100u. I put a new 100u in.
It is my first real attempt troubleshooting and it is gonna take some time. Thats ok.
I use the schematic and try to follow the traces.
I measure 8.95 volt and around 5,6 volt??? after the voltage divider
Have to take at look what I put at D1
C20 in the schematic is a 47u but on the board it was 100u. I put a new 100u in.
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Schematic is not right. The burned 100u has no number en the c20 is c21 on the board.
I dont understand how I can measure 5,6 volt on all three lugs of the level pot.
The pot itself measures 85 k on the outside logs and middle log measures 85k maxed out both settings. So the potential on all lugs are the same?
IC pin 8 =8.95v
Pin 5 = 5,6v
Pin 4 is ground
I removed the IC. Still potential on all levelpot lugs are 5,6 v
I dont understand how I can measure 5,6 volt on all three lugs of the level pot.
The pot itself measures 85 k on the outside logs and middle log measures 85k maxed out both settings. So the potential on all lugs are the same?
IC pin 8 =8.95v
Pin 5 = 5,6v
Pin 4 is ground
I removed the IC. Still potential on all levelpot lugs are 5,6 v
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Robert
Reverse Engineer
That's normal.
Lug 1 is connected directly to VREF.
Lugs 2 and 3 are both effectively open to DC voltage due to being capacitively coupled to the stages before/after so they float up to the same potential as lug 1.
Log =lug haha
Forgot to mention bypassed signal works.
Are the two jfets working as a flip flop? So one is open the other closed?
Edit:
Yes flip flop. I surprise myself understanding a little bit more than I thought:
Forgot to mention bypassed signal works.
Are the two jfets working as a flip flop? So one is open the other closed?
Edit:
Yes flip flop. I surprise myself understanding a little bit more than I thought:
Last edited:
Sturdag Lagernathy
Well-known member
Probably just a manufacturers mark. Does it rub off easily?
Capacitor goo, (IME) is usually a nasty, brownish color and leaks from the bottom. The cap will also usually be misshapen, though this can be subtle.
hamerfan
Well-known member
RC4558P Dual Op Amp
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