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dom75011
Copper Member
France
19 Posts |
 Posted - 10/12/2009 : 12:26:17
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I've just purchased on e-bay a non working DD-2.
Using a new battery, the switch has no effect, the led doesn't light on, the clean signal is still there (and working) on the mono output.
I got the schematic and checked:
the switch : OK
9v : OK on several pcb checks.
5v : OK on several pcb checks.
When switching is see IC9 IN pin 1 going from 9V to ground. But OUT pin 2 doesn't move.
After a few minutes, the battery gets hot and the voltage drops down (8,6v)
What should I check next?
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 10/12/2009 : 16:37:23
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Hello dom75011 and welcome!
The symptoms you describe are very strange... A hot battery is amost always associated with D6 burning out in these pedals, however, if D6 is burned out you will not get 9V anywhere on the board.
First, and just to rule it out, can you check the resistance across D6?
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dom75011
Copper Member
France
19 Posts |
Posted - 10/12/2009 : 19:25:04
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D6 on board, not unsoldered : 7,2K
When on "hold", pushing the switch, the led lights on, but clean signal out of mono output
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 10/12/2009 : 19:33:29
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Ok. Are you only using the battery, or do you also have a power supply plugged in?
A quick test - plug the output lead into the "direct" jack. Do you get a clean, non-delayed signal?
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dom75011
Copper Member
France
19 Posts |
Posted - 10/12/2009 : 19:39:02
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I'm using only a battery, I don't have a roland ps.
The signal from the direct output jack is clean too. |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 10/12/2009 : 19:42:55
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Yet the battery is getting hot... If the pedal had failed so completely that the battery was getting hot, you should not get any sound out of it at all.
Are you able to measure current from the battery? Perhaps unclip one side of the battery and put your multimeter between the unclipped terminals - this will let us see how many milli-amps are flowing out of the battery. |
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dom75011
Copper Member
France
19 Posts |
Posted - 10/12/2009 : 19:49:18
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The battery was not very very hot, but was hot
current = 50 ma |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 10/12/2009 : 21:31:08
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| OK. 50mA is the actual expected current so no problem there. Let me think on this some more. |
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dom75011
Copper Member
France
19 Posts |
Posted - 10/12/2009 : 23:42:01
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| I can see on the coper side of the pcb that D6 and IC10 had been previously replaced |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 10/13/2009 : 00:05:08
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quote:
Originally posted by dom75011
I can see on the coper side of the pcb that D6 and IC10 had been previously replaced
Hmmm... sounds like it was plugged into the wrong voltage at some point and something was burned out.
Let's focus back onto IC9. What is the voltage on pin 5? If you watch the voltage on pin 5 when you connect the battery (or plug a lead into the input) do you see it change after about 5 seconds?
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dom75011
Copper Member
France
19 Posts |
Posted - 10/13/2009 : 09:04:04
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IC9, pin 5: 0.05v, then after 3 sec, 8.02v
I already stated that pushing the switch, pin 1 goes to 0v, but pin 2 stay at 0.22v : maybe a component is shorted to ground after that pin, but I don't see any candidate.
I hope that the BA634 is not faulty, because it is no more available.
I've also tested the test point 4 (Q9-R44) : no signal
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 10/13/2009 : 14:06:32
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Let's not blame IC-9 just yet... I've never seen a dead IC-9 on one of these pedals.
I've had several of these pedals with failed mode switches. Can you check the mode switch is switching properly by measuring the resistance across the contacts in each position?
If it eventually turns out IC-9 is actually dead, you can get them here:
http://www.vintageplanet.nl/semiconductors.html |
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dom75011
Copper Member
France
19 Posts |
Posted - 10/13/2009 : 16:04:00
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I will check the mode switch this evening (here in France).
What is the voltage I should read on pin 2 of IC9 when "on" and "off"? I think that I should have some 9v when "on"
After disconecting the wire between pin 2 and the sw board, can I simulate a working IC9 ? How?
Vintageplanet.nl ask for a $15 order minimum ...
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 10/13/2009 : 16:15:18
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quote:
Originally posted by dom75011
I will check the mode switch this evening (here in France).
What is the voltage I should read on pin 2 of IC9 when "on" and "off"? I think that I should have some 9v when "on"
After disconecting the wire between pin 2 and the sw board, can I simulate a working IC9 ? How?
Vintageplanet.nl ask for a $15 order minimum ...
9V for "ON", zero for "OFF".
Disconnect the wire going to terminal "3" on the main board. Set the mode switch to anything but "H". Hold the wire that went to terminal "3" to ground to simulate "off", and to the positive battery terminal to simulate "ON". If the pedal performs properly (LED comes on, delay sound is OK) when the wire from pin "3" is held to 9V then the problem is with IC-9. If it does not work properly, then the problem is not IC-9.
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dom75011
Copper Member
France
19 Posts |
Posted - 10/13/2009 : 20:11:02
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Back home
I unsoldered the terminal 3 which is connected to pin 2 of IC9, then connected the terminal 3 to +9v to simulate "on". The led lights on now, but I do not have any delay sound.
To be certain, I've put a jack in the direct output: no signal is coming from mono output.
weird!
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 10/14/2009 : 06:18:50
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quote:
Originally posted by dom75011
Back home
I unsoldered the terminal 3 which is connected to pin 2 of IC9, then connected the terminal 3 to +9v to simulate "on". The led lights on now, but I do not have any delay sound.
To be certain, I've put a jack in the direct output: no signal is coming from mono output.
weird!
OK, so the LED goes on, but nothing works...
To confirm - with the LED on, and a lead in the "direct" jack but no lead in the "out" jack, there is no signal on the direct out?
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Topic |
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Boss DD-2 not switching on
