Fried Klon Zeners

Svenson007

Active member
Hey guys I asked a question I thought I knew the answer to a while ago here to confirm before building a Klon for somebody. It was confirmed. I asked if a 12v 1n5242 1/2 watt Zener diode was ok instead of the 1watt version. I didn’t and other people didn’t see a problem. Well one fried while I was testing it with one 9v adapter. I fixed it and played it with an ehx adapter no problem. I sold one of the two builds and when the guy got it he said he plugged in a one spot and it won’t work.

Why would this diode fail like that?? It’s super disappointing as I’ve never had a build fail like that and he seems annoyed and is getting his money back. I don’t think he’s open to clipping the diode and having me guarantee that if anything happens to the chip it’s on me.

I knew I should have left it out and just risked the chip… as it can handle plenty of power.

So my question again is. Why the heck wound these zeners be failing?
 
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You couldn't power the circuit (properly) at 9V because of regulator dropout.

The Klon is one of the only circuits I know of that even bothers to attempt to protect the charge pump from over-voltage.... I'd be tempted to just omit the zener altogether.
Every VFE pedal would like to have a word with you.
 
I just wanted to build it as an exact clone. Also I wasn’t sure if maybe there was a reason for it that would be circuit dependant. Like a high pitched whine etc. I have some alternate charge pumps around. I’ll give em a try. I have used the max before with no problems, but I’ve also heard plenty of horror stories. I hate using components that are pushing it tolerance wise.
The Klon only used 7660SCPA, not Max1044!!!!!
Here is the most accurate PCB below :

KLONE PCB.jpg
 
Any reason you couldn’t just use an LM317 with a 240 Ω and 1.5K Ω resistor pair to regulate anything up to 40V down to 9.06V before the charge pump? It would only add three components, and instead of frying from over voltage like the zener, it would just step every down to a level that’s consistently safe for the charge pump circuit. Am I missing something?

Toan = mojo…
 
You couldn't power the circuit (properly) at 9V because of regulator dropout.

The Klon is one of the only circuits I know of that even bothers to attempt to protect the charge pump from over-voltage.... I'd be tempted to just omit the zener altogether.
I know why from First Hand experience, Took me around 2hrs with a dremel to get the Black Goop off that Klon fried 7660S Charge Pump after the 1N4742 was clipped after receiving 18 volts !!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
I just wanted to build it as an exact clone. Also I wasn’t sure if maybe there was a reason for it that would be circuit dependant. Like a high pitched whine etc. I have some alternate charge pumps around. I’ll give em a try. I have used the max before with no problems, but I’ve also heard plenty of horror stories. I hate using components that are pushing it tolerance wise.
Trust me, Change to the 7660SCPAZ, I have never had an Issue with around 50 Builds using them!!!
 
You couldn't power the circuit (properly) at 9V because of regulator dropout.

The Klon is one of the only circuits I know of that even bothers to attempt to protect the charge pump from over-voltage.... I'd be tempted to just omit the zener altogether.
I did omit it on my last build. Smooth sailing so far.
 
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