Dunlop CryBaby GCB-95... Battery and Black Magic!

Frequently asked questions regarding powering your pedal.
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Pantegana
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Post by Pantegana »

I don't know if it's my fault, if I messed up something when i modded my crybaby.. but:

if I use it with a battery inside works well, if I use it with battery & external power supply it's all ok,
if I use it without a battery, only with a PSU in bypass (buffered, not TB) the signal passes, when I
switch on the effect it mutes...

It's normal? :hmmm: must I call an exorcist?
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Paul Marossy
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Post by Paul Marossy »

Pantegana wrote:I don't know if it's my fault, if I messed up something when i modded my crybaby.. but:

if I use it with a battery inside works well, if I use it with battery & external power supply it's all ok,
if I use it without a battery, only with a PSU in bypass (buffered, not TB) the signal passes, when I
switch on the effect it mutes...

It's normal? :hmmm: must I call an exorcist?
No, that's not normal for it to do that. What exactly did you mod?
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gus
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Post by gus »

It works when the battery is installed, battery alone or battery and external power battery is common to both. It does not work with external power and no battery installed. Reads like the external supply is not connected correctly.

Check the battery and external power wiring to start and any part of the wiring you moved when you worked on the wha.
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Post by Paul Marossy »

gus wrote:It works when the battery is installed, battery alone or battery and external power battery is common to both. It does not work with external power and no battery installed. Reads like the external supply is not connected correctly.

Check the battery and external power wiring to start and any part of the wiring you moved when you worked on the wha.
What?! That is weird.

Every pedal I have ever built or any other commercial pedal I have used simply switches the battery out of the circuit when you plug a cord into the DC jack. In fact, I can not even have a battery in there and it doesn't matter. I wonder why it matters on the GCB-95? :scratch:
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Pantegana
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Post by Pantegana »

Paul Marossy wrote:I wonder why it matters on the GCB-95? :scratch:
Me too...
Paul Marossy wrote:What exactly did you mod?
Just a Cap and a couple of resistors. Input buffer and bypass still there as mother Dunlop made them...

I know it's demented but I will try a dead battery and see what happens...
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Post by Paul Marossy »

Huh, that is pretty unusual. I hate it when I have to eat my words! :?
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Post by gus »

First did the wha work before the mods with the battery and with external supply alone? If so it is something that was done during the mods. Think back to what was removed and what was changed.

When working on a effect take a picture(s) or draw the wiring and mark wire colors and connections points to make sure you can restore the effect to stock if you need to.

Yes the battery is switched out and power is supplied from the external supply when plugged in but it reads like this is not happening with this wha if I understand the first post correctly.

To test if the +9VDC external power is not connected correctly or the wrong polarity connector . Use a Meter to measure the +9VDC at the board +9VDC and ground. Wha alone nothing plugged in with the battery should have no voltage, insert a plug into the input jack you should get +9VDC. Plug in the external supply do the same test. Remove the battery do the same test.

Is the supply +9VDC and the correct polarity?
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Pantegana
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Post by Pantegana »

gus wrote:First did the wha work before the mods with the battery and with external supply alone?
Dunno... never tried with a psu before modding...
Power source is an ARTEC D.C. brick, standard polarity (all the others 7 fx works correctly).

Just a thing... Anyone knows what is the current draw of the crybaby when the effects is on? Each plug of the DC brick offer a maximum of 100 or 125 mA...

I wonder if the crybaby, when switched on, draws too much current and the PSU suspends the power... :hmmm:
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Post by Paul Marossy »

I wonder if the crybaby, when switched on, draws too much current and the PSU suspends the power...
No, it would just drop the voltage supplied by your power transformer a little bit. A CryBaby uses very little current, it's only four transistors that are getting power.
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Post by tlpruitt »

Make sure the contacts on the battery snap are not touching anything when you use it without a battery. Put a piece of tape over the contacts on the battery snap.
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Post by Pantegana »

tlpruitt wrote:Make sure the contacts on the battery snap are not touching anything when you use it without a battery. Put a piece of tape over the contacts on the battery snap.
But in this case the pedal should not work also in bypass...

In the crybaby the insertion of the DC plug causes the battery to be excluded from the circuit?

In this case maybe there is an interruption between the +9 of the DC socket and the "effect" but not the bypass...
Or maybe a "mechanical" problem, upon hitting the button something shorts and when hitting again it does not more...

:?: :?: :?: :?:
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Post by Paul Marossy »

In the crybaby the insertion of the DC plug causes the battery to be excluded from the circuit?
That's standard for any effect pedal that can operate on a battery or a DC power supply. You plug a wall wart into the DC jack, and it simply switches the battery out of the circuit via the internal switch on the DC jack. At that point, whether or not a battery is connected to the battery snap should matter. And it also doesn't matter if you have the battery snap touching the inside of the pedal or not because the positive is no longer connected to the circuitboard.

That's normal wiring for effects pedals...
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Post by Paul Marossy »

Oops, what I meant to say was: "At that point, whether or not a battery is connected to the battery snap should NOT matter."
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Post by reubster »

I don't know how the DC jack on a GCB wah is wired, but many pedals use the DC Jack switching on the the gnd connection.
Therefore the battery clips +ve would have 9 volts on it sourced from the external supply.
Whilst a short circuit of the + of the battery clip to the case seems "physically" unlikely, it would actually explain the problem.
Easy enough to check, just hang it outside the case and wukka wukka away.
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Post by Fuzzer »

No, DC Jacks break the connection for the positive side of the battery. Otherwise you'd have shorts between V+ and Ground anytime the snap touched the pedal's case, which I think is not that unlikely.
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Post by Paul Marossy »

Fuzzer wrote:No, DC Jacks break the connection for the positive side of the battery.
Yep, that's convention...
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