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curefan
Copper Member
Germany
16 Posts |
 Posted - 11/21/2005 : 20:57:15
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Hello,
I�ve got some technical problems with an old CE-2 Chorus.
Let me explain what happens when I use it both with a battery and
adapter.
When I use this pedal with battery at the beginning,
the LED is on and you can hear a wonderful chorus sound,
several minutes later the LED begins to fade until there�s no red
light anymore. The chorus-sound also dissapears. Then it looks and
sounds as if there would be a weak battery! But I can�t be
a weak battery, because this battery works fine with other pedals.
When using the pedal with an adapter, there�s no LED light and
I can only hear the unmodified guitar sound!
Can anyone explain this situation?
P.S This is a very old pedal with silver screw and serial-No. 8800
Thanks,
Curefan |
Edited by - curefan on 11/21/2005 20:58:24 |
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bossarea
Forum Admin
United Kingdom
3652 Posts |
Posted - 11/21/2005 : 21:55:57
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Strange that it works differently with an adapter than when battery powered. The problem must be in the power supply part of the pedal somewhere. If it was elsewhere the LED should light up properly at all times.
I suspect he problem may be with one of the 2 caps connected to the power inlet. These may have dried out over the years. If you have a multimeter I would start by measuring the voltage on both sides of the 33 Ohm resistor between these two caps. If it's below 9V, replace the capacitors. |
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curefan
Copper Member
Germany
16 Posts |
Posted - 11/22/2005 : 17:45:46
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Thanks for your help!
Perhaps there are two different problems! Who knows...?
Curefan |
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stahlhart
Platinum Member
1318 Posts |
Posted - 11/22/2005 : 21:34:30
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In looking at the schematic, my first suspicion regarding battery power would be D7, which I'm guessing is a 9.1V Zener. There are also two filtering capacitors (C29 and C30), which could also potentially be a problem. for battery power, they don't even need to be there -- they're probably only for filtering ripple fromm the AC adapter, if one is used. For that matter, the Zener isn't necessary for battery power either. If it were me, I'd probably try removeing all three of these from the circuit board to make sure that none of them are shorting battery power to ground -- perhaps the Zener is okay cold, but develops a problem after power has been applied to it for a while?
Also, note that there is D5, which looks like a reverse-polarity protect diode -- if this were bad (i.e. open), it might explain why the CE-2 does not work with an AC adapter. I'm not sure, however, if it would have any effect on running the CE-2 from a battery.
Mabye a previous owner attempted to run this pedal with the wrong adapter and took out one or more of these power supply related components?
C.K.
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Technical problems with CE-2 Chorus
