Any recommendations where to go next repairing Metal Zone



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Any recommendations where to go next repairing Metal Zone

Postby Psyre » Fri Jun 08, 2018 5:33 pm

Hey guys, I've been battling a dead metal zone for about 3 months now (replacement parts not arriving and other horse shit)

I received it $3 above value only to find it had a blown psa input diode.

So far I have replaced the diode as well as all 4 OPamps but still only getting output when bypassed. Nothing looks blown or burnt even. Every case on the net I have seen was either just the diode or opamps, so now I'm a little lost as to where to look next. I really want to just toss it, but I can't bring myself to a loss just yet :cry:

Anyone else repair a similarly fucked boss dirt?
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Re: Any recommendations where to go next repairing Metal Zon

Postby BetterOffShred » Sun Jun 10, 2018 1:53 pm

Dude so this isn't helpful but I'd just buy another used one. They go for really cheap when you have a little patience. Boss pedals are a nightmare imo.
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Re: Any recommendations where to go next repairing Metal Zon

Postby Dr Satan » Sun Jun 10, 2018 2:07 pm

Probably 10 cents worth of JFET that's failed on the effect side of the bypass switching. That's where I'd look at least.
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Re: Any recommendations where to go next repairing Metal Zon

Postby Paul_C » Sun Jun 10, 2018 2:17 pm

switch ?
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Re: Any recommendations where to go next repairing Metal Zon

Postby Dr Satan » Tue Jun 12, 2018 11:25 pm

If the light is coming on, and it's changing state from bypass to nothing, that would indicate the state variable switch is functional. It could be some other thing, like a diode going to the JFETs, the bias network is possibly out of wack, another blown diode or resistor, or a handful of other things, but the JFETs wear more than anything else because they are being used as switches. Passive components other than electrolytic and tantalum caps, or resistors that dissipate a lot of energy as heat don't typically wear out for many, many years. Sure, imperfections in the manufacturing process contribute to that so nothing is ever 100%, but on average, discreet components fail more often than passive.
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Re: Any recommendations where to go next repairing Metal Zon

Postby Psyre » Thu Jun 14, 2018 10:16 am

Looks like JFET is where to go next then. Will have to do some probing. Thanks
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Re: Any recommendations where to go next repairing Metal Zon

Postby crochambeau » Thu Jun 14, 2018 12:05 pm

Psyre wrote:Will have to do some probing. Thanks


Yeah, if you have an audio probe or 0-scope you can follow the signal to the point at which it drops off the map, and then troubleshoot sections immediately before or ahead of that point.
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