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Mesjoggah
Gold Member
Netherlands
595 Posts |
 Posted - 07/31/2009 : 22:10:13
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| I have this MIJ DS-1, the LED comes on when the pedal is pressed but no sound comes through, suggestions where to look first? |
Edited by - Mesjoggah on 08/14/2009 18:23:50 |
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cctsim
Silver Member
United Kingdom
418 Posts |
Posted - 08/01/2009 : 00:38:08
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If it works in bypass mode then I would check Q6.
Check also if any cable has come off. |
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Mesjoggah
Gold Member
Netherlands
595 Posts |
Posted - 08/01/2009 : 05:53:58
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| It doesn't work in neither mode, there's just no signal coming through. Q1 isn't switching, thats all i know. |
Edited by - Mesjoggah on 08/01/2009 06:47:10 |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 08/01/2009 : 07:16:47
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Well... Q1 doesn't actually "switch". If you mean there is no signal at the emitter of Q1, then that makes sense.
If that's the case, C1 is open circuit, or Q1 is dead, or R3 is open circuit.
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Mesjoggah
Gold Member
Netherlands
595 Posts |
Posted - 08/01/2009 : 17:12:05
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quote:
Originally posted by Laurie
Well... Q1 doesn't actually "switch". If you mean there is no signal at the emitter of Q1, then that makes sense.
If that's the case, C1 is open circuit, or Q1 is dead, or R3 is open circuit.
That is the case Laurie, Q1, C1 and R3 seem to be OK. Gonna probe and switch some components tomorrow (already replaced Q1 but no luck) |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 08/01/2009 : 17:51:13
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Hi Mesjoggah
You may want to consider probing the circuit from output, back towards the input.
(with a signal injected into the input)
And then see in which section the signal is getting lost.
This is common practice with amp circuits. & can quickly direct you to the faulty section.
If you have a second similar unit, you could use this as a reference.
Good Luck
Regards Dr. Bob  |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 08/02/2009 : 08:23:05
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quote:
Originally posted by Mesjoggah
That is the case Laurie, Q1, C1 and R3 seem to be OK. Gonna probe and switch some components tomorrow (already replaced Q1 but no luck)
If there is no signal at the emitter of Q1, the options are limited... It has to be the input jack, the wire across to the board, or a break/dry joint on the board somewhere.
Is there signal at "connection point #1" on the board?
What's the voltage across C15.... ? |
Edited by - Laurie on 08/02/2009 08:23:51 |
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Mesjoggah
Gold Member
Netherlands
595 Posts |
Posted - 08/02/2009 : 10:49:35
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quote:
Originally posted by Laurie
quote:
Originally posted by Mesjoggah
That is the case Laurie, Q1, C1 and R3 seem to be OK. Gonna probe and switch some components tomorrow (already replaced Q1 but no luck)
If there is no signal at the emitter of Q1, the options are limited... It has to be the input jack, the wire across to the board, or a break/dry joint on the board somewhere.
Is there signal at "connection point #1" on the board? YES
What's the voltage across C15.... ? ZERO
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 08/02/2009 : 16:41:48
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quote:
Originally posted by Mesjoggah
What's the voltage across C15.... ? ZERO
The 4.5V rail has failed....... (I remember another pedal like that! )
Check R24:
1) is it open circuit (failed)?
2) is it getting 9VDC supply? - does the end of R24 that isn't connected to R25 have 9V on it
Also measure the resistance across R25 - leave it in circuit and measure. Is it zero Ohms? (short)
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Edited by - Laurie on 08/02/2009 16:43:55 |
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Mesjoggah
Gold Member
Netherlands
595 Posts |
Posted - 08/02/2009 : 17:25:16
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quote:
Originally posted by Laurie
quote:
Originally posted by Mesjoggah
What's the voltage across C15.... ? ZERO
The 4.5V rail has failed....... (I remember another pedal like that! ) i think it was some kind of yellow pedal...
Check R24:
1) is it open circuit (failed)?
2) is it getting 9VDC supply? - does the end of R24 that isn't connected to R25 have 9V on it the end that isn't connected has 9v on it, the other site of R24 is zero
Also measure the resistance across R25 - leave it in circuit and measure. Is it zero Ohms? (short) zero ohms
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 08/02/2009 : 18:18:39
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quote:
Originally posted by Mesjoggah
2) is it getting 9VDC supply? - does the end of R24 that isn't connected to R25 have 9V on it the end that isn't connected has 9v on it, the other site of R24 is zero
Also measure the resistance across R25 - leave it in circuit and measure. Is it zero Ohms? (short) zero ohms
OK... there is a short on the 4.5V rail. Somewhere on the trace that the positive leg of C15 connects to there is a short to ground.
1) remove C15 - is it still zero Ohms across R25?
2) Carefully check for solder "dags" shorting the 4.5V trace to ground.
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Mesjoggah
Gold Member
Netherlands
595 Posts |
Posted - 08/03/2009 : 17:15:13
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quote:
Originally posted by Laurie
quote:
Originally posted by Mesjoggah
2) is it getting 9VDC supply? - does the end of R24 that isn't connected to R25 have 9V on it the end that isn't connected has 9v on it, the other site of R24 is zero
Also measure the resistance across R25 - leave it in circuit and measure. Is it zero Ohms? (short) zero ohms
OK... there is a short on the 4.5V rail. Somewhere on the trace that the positive leg of C15 connects to there is a short to ground.
1) remove C15 - is it still zero Ohms across R25? Still zero Ohms
2) Carefully check for solder "dags" shorting the 4.5V trace to ground. nothing suspicious... yet
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 08/03/2009 : 17:37:39
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quote:
Originally posted by Mesjoggah
2) Carefully check for solder "dags" shorting the 4.5V trace to ground. nothing suspicious... yet
It's down to your detective skills now 
Let us know what the culprit is when you find it... |
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Desoldering Boy
Copper Member
Pakistan
23 Posts |
Posted - 08/04/2009 : 15:03:23
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| I've experienced this on a BOSS MT-2, please check the opamp, you can pull it out, and compare its terminal resistances with respect to its GND or V+, and compare it to a good Opamp... |
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Mesjoggah
Gold Member
Netherlands
595 Posts |
Posted - 08/06/2009 : 16:55:37
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| i don't think it is the opamp, i have distortion now but the volume is too low. |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 08/11/2009 : 16:06:39
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| G'day! Any progress on this one? Enquiring minds want to know.... |
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Topic |
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DS-1 no signal - PROBLEM SOLVED!!!!!!
