A neighbor referred a friend to me to look at his MXR EVH Phase 90 that didn't work. I figured it would be a loose pad on jack/switch/pot etc.,. I plugged it in and if I hit a chord hard I'd get a nastly "blatttt" and that was it. I pulled it apart and found it was all SMD construction. All the jack, pot and footswitch connections on the PCB are solid. My guess is an opamp went bad? I checked the power supply diodes which seem to be a problem when hooked up to the wrong type adapter, and they are in good shape. LED works when switched on.
In any case, I've built many tube amps and pedals and repaired a few over the years but never have worked with SMD devices and don't have the proper tools or the patience to do it. I'm going to suggest he either buy a used one or take it to a pro shop for repair. But I'm thinking the labor may be close to the cost of a used one. I've never paid anyone for an amp or pedal repair so I have no idea what minimum bench charges are these days. Any thoughts?
Bench charge for pedal SMD repair??
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plush
- Cap Cooler
casey73 wrote:A neighbor referred a friend to me to look at his MXR EVH Phase 90 that didn't work. I figured it would be a loose pad on jack/switch/pot etc.,. I plugged it in and if I hit a chord hard I'd get a nastly "blatttt" and that was it. I pulled it apart and found it was all SMD construction. All the jack, pot and footswitch connections on the PCB are solid. My guess is an opamp went bad? I checked the power supply diodes which seem to be a problem when hooked up to the wrong type adapter, and they are in good shape. LED works when switched on.
In any case, I've built many tube amps and pedals and repaired a few over the years but never have worked with SMD devices and don't have the proper tools or the patience to do it. I'm going to suggest he either buy a used one or take it to a pro shop for repair. But I'm thinking the labor may be close to the cost of a used one. I've never paid anyone for an amp or pedal repair so I have no idea what minimum bench charges are these days. Any thoughts?
I've recently had a chance to repair phase 90 (smd). Same thing - gated "prrrttt" and no clean sound.
Guy managed to blow both opamps with wrong PSU polarity, you can clearly see holes in them. Internal short made both of them to pull vcc down to almost zero. Pretty common situation due to shitty reverse polarity protection - thx, MXR.
It's quite easy fix and it takes 5-10 cm of solder wick ang couple of bucks for opamps (rail2rail is really not that not mandatory, but I'd opt for it - it can help in some situations to reduce signal clipping).
I've charged just the components, because it was fun and took me roughly 20 minutes.
As for the minimum bench charge - it depends on a lot of stuff. If you are making living from it, then you already know the thing. If not, 10-20$ (depending on where you are living) w/o parts seems like a good start.
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Thanks for the tip. I'll take a second look. The opamps looked in tact but maybe I missed it. I've read that reverse polarity usually takes out a diode or two near the power jack but they look fine. I do this as a hobby now (retired) so I won't charge much (maybe 12 pack of beer or toilet paper) if I actually fix it.
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plush
- Cap Cooler
Yeah, they usually do, bun not in this case, unfortunately.casey73 wrote: I've read that reverse polarity usually takes out a diode or two near the power jack but they look fine
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alexradium
- Resistor Ronker
i repaired several smd pedals,the phase 90 had exactly the opamp fried.casey73 wrote:Thanks for the tip. I'll take a second look. The opamps looked in tact but maybe I missed it. I've read that reverse polarity usually takes out a diode or two near the power jack but they look fine. I do this as a hobby now (retired) so I won't charge much (maybe 12 pack of beer or toilet paper) if I actually fix it.
Its not a big deal once you have the necessary tools: hot air station,magnifier lenses or microscope,tweezers,flux,solder wick,cleaning liquid.
You can work on it anyway with a normal soldering station,or better 2.
For a proper tech it is a half hour job,check included.