Digitech Whammy WH-4 won't power on

[space_ryerson]

I briefly mentioned this in another thread a while back, but I have a Digitech Whammy WH-4 which won't turn on. When the power supply is plugged in, the LEDs blink for a second, then turn off. I've tried two different power supplies, checked for any bad components and solder joints, but haven't found the culprit yet.

In the other thread, Processaurus mentioned that it likely isn't the power supply causing the problem, and that I should have a look at the outputs of the regulators. After getting some odd readings, I decided to trace out the power section:

My first problem is that I don't know what L1 and L2 are. They look like little ferrite beads with leads through them. I measured no resistance, and the diode test showed conductivity in both directions. Here's what they look like:

What are they?

My second problem is that the part number I read off one of the regulators, U1, doesn't seem to correspond to any googling I do, so I can't find a datasheet and I don't know what to expect to see voltage wise. I can't replace it without a part number! Does anyone know what a LD33V WCC1A0105 is?

Currently, out of the power supply I'm getting about 9.7VAC. Right after D1, I'm getting 9.04V DC. For U1, I'm reading input: 4.47V and output: 1.3V. For U2 (7805), I'm reading input: 12.8V, output: .16 - .19V (fluctuating in between). For U3 (7905), I'm reading input: -13.9V and output: -4.9V.

I'm not at all versed with regulators, but the 7905 seems fine, and the 7805 doesn't; but if I'm reading the datasheet correctly, it's receiving more voltage than it's rated for. For U1, I have no idea what I should be reading.

I would love to get this working. Does anyone have any ideas?

[joegagan]

not familiar with the part numbers, but a long time ago i found that digitech whammy pedals are picky, for some reason they need the digitech power supply. are you using the exact one they recommend?

[anchovie]

I've run a Whammy IV off a no-name 9VAC PSU and it was fine.

If you Google LD33V on its own (the other stuff is most likely a manufacturing/batch/date code) you'll find out it's the marking for a 3.3V regulator, so you've got that and the 7805 not putting out the right regulated voltage. I would suspect that someone plugged an inappropriate DC supply into the socket, as both your + voltages are shot but the -5V is fine (thanks to the rectifier diode being reversed polarity, so DC would have been blocked).

The 7805 datasheet that I just checked says it's got an absolute maximum input of 35V so there isn't an issue there.

[space_ryerson]

Thanks Anchovie! It was given to me broken, so I have no idea what the history of it is. I'll definitely replace those two regulators. Is there any need to replace everything else? I don't have a method of testing the caps, but the diodes seem fine.

Joe, I've tested two different working PS's. One is the Digitech PS for a WH-2, and the other is 9VAC/1.3 amp.

Any idea what L1 and L2 are?

[MarcoMike]

they look like ferrite things... I think used to get rid of interferences...

[MoltenVoltage]

L is the symbol for an inductor, so they are some sort of inductor.  Since they are a pretty sturdy passive component, there are probably not the source of your problem.

The big problem with trying to troubleshoot digital effects is that a bad surge of electricity could have zapped a chip.

One Whammy that I repaired had a blown power supply cap.  I would check those first thing, especially if its an older unit.

[markeebee]

I have a WH-4 with EXACTLY the same symptoms. Bought it as a dud, previous owner admitted he plugged in the wrong power supply.

The consensus on this and other various forums was that there's a very very very strong chance that the logic chip will have been duffed. Unfortunately, the chip and coding are unique to Digitech, and aren't available to buy.

At that point it went to the bottom of the pile of things to fix.

Space - you are obviously built of stronger stuff than me. If you find a fix, please can you post it here so that I can copy you?

[markeebee]

@Space - sorry, forgot to say, if you want me to help bt trying stuff on my unit so that you don't have to sacrifice yours, no problem. And I'd be happy to help in any other way.

Oh....those ferrites are there to attenuate high frequency noise, such as line-borne RFI.

[space_ryerson]

L is the symbol for an inductor, so they are some sort of inductor.  Since they are a pretty sturdy passive component, there are probably not the source of your problem.

Thanks! Makes sense to me.

The big problem with trying to troubleshoot digital effects is that a bad surge of electricity could have zapped a chip.

One Whammy that I repaired had a blown power supply cap.  I would check those first thing, especially if its an older unit.

I'll give that a try first, since I have to order and wait for the regulators anyway.

I have a WH-4 with EXACTLY the same symptoms. Bought it as a dud, previous owner admitted he plugged in the wrong power supply.

The consensus on this and other various forums was that there's a very very very strong chance that the logic chip will have been duffed. Unfortunately, the chip and coding are unique to Digitech, and aren't available to buy.

At that point it went to the bottom of the pile of things to fix.

Space - you are obviously built of stronger stuff than me. If you find a fix, please can you post it here so that I can copy you?

Thanks for the compliment If I find a fix, I'll definitely let you know. I had some initial problems sourcing a LD33V, but found one. If the logic chip is fried, then so be it; but there's only one way to find out! It's odd that the WH-4 could be killed like that. I have a WH-2, and as a teenager, I accidentally plugged a 9V DC adaptor into it, and it didn't kill it!

[bside2234]

I have one that is doing the exact same thing. L1 - L3 are 70 ohm @ 100 MHz ferrite beads.

[Dirk_Hendrik]

I have a WH-4 with EXACTLY the same symptoms.

Chimin'in!  Same problem here. So far I haven't been able to relate the problem to the supply power in any way. CPU adress and dataline scoping shows activity on bootup that dies after a few seconds, leaving the thing completely dead.

I've seen more references to this problem and suspect it's far more common than we know.

[bside2234]

I'm just starting to dig into mine but I too am not seeing a power supply issue.

[ppatchmods]

i have the same problem with mine. bought a new digitech power supply with the same results. the interesting thing is that i true bypassed it some time ago(it was having the problem before this) and when the power to the pedal shuts off, the led for the TB stays on. that wouldn't be so weird but the led power is taken off of a point on the board that supplies 5v+. don't know what to think.

[space_ryerson]

Wow. I didn't think it was this common of a problem. In my case, there definitely seems to be something wrong with the power supply, but the jury is out on the CPU. When the replacement regulators arrive I'll report back. I didn't have any spare 1,000uf caps laying around, so I didn't get to see if that helped.

[bside2234]

Well, just for reference, I looked at my friends Whammy 4 and upon power up on his, the LED's blink on and off (as in what ours seem to be doing) and then the Effect LED and the effect selected LED light up. It seems our problem is after the initial power up.

[ppatchmods]

i agree it's after power up. my problem leads me to believe it is having trouble sending power to the chip and selector part of the pedal. that is the only reason the led for the TB would still light up...that i can figure...
my thought is that it is a cap that is having trouble storing the power or something. i stink at trouble shooting!

[space_ryerson]

Well, I replaced the regulators and capacitors in question, and now they all put out the correct voltage. The bad news is that it does the same thing on power up (lights flash on quickly, then out), but now the LED for the LDR at least stays on...So I'm thinking the logic chip is likely fried. Crud.

[markeebee]

Ohhhhhhh, bad news!   Thanks for taking the hit for us.

Still, nice home for a wah or whatever. As a last resort, I was thinking that I might buy the Behringer US600 pitch shifter thing and rehouse it in the whammy case, using a LDR thing as an expression pedal thing.  Kind of whammy junior.

[ppatchmods]

question: can the chip be "going out" or will it either work or not work? mine works sometimes and then other times it doesn't. i think i will email digitech and see what they have to say about it.

[MoltenVoltage]

question: can the chip be "going out" or will it either work or not work? mine works sometimes and then other times it doesn't. i think i will email digitech and see what they have to say about it.

In my experience, chips either work or they don't.

If its working normally sometimes but not others, there is a 95% chance that the problem is NOT with the chip.