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Dave Simpson
Copper Member
USA
9 Posts |
 Posted - 04/22/2007 : 20:22:58
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Anyone have a suggestion on what I should check? All the other sliders work normally, just the 100 Hz slider is dead. Any advice would be appreciated. |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 04/23/2007 : 10:41:42
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quote:
Originally posted by Dave Simpson
Anyone have a suggestion on what I should check? All the other sliders work normally, just the 100 Hz slider is dead.Any advice would be appreciated.
Hi Dave Simpson
Look for dry cracked or cold solder joints on the 3 connections to the slide pot.
If you have a multimeter, measure across the two ends of the pot, it will be approx 10K ohms or 10,000 ohms
In fact all the pots on the GE-7 schematic that I have, are 10K linear taper.
{ later note: This may not be a good place to start measuring, as I just noticed, that all the ends of the pots, are wired in parallel.}
Then measure from any end to the center terminal (the wiper) or the pin that connect to the moving part of the slide pot.
when the slider in in the center dent position, you should get about 5K from the center to each side.
If you move the slider, to a different position, you will get different readings, between the center & either end of the pot.
if you get no reading, from center to either side, then the pot is faulty.
Boss GE-7 pots are pretty tough,
so I might guess that it's a bad solder joint, or you have spilled something into the pot, maybe beer or coke, from a wild jig?
Also look for a cracked PCB copper track.
or the solder joints around capacitor C10 it's a 1.5uf tantalum cap.
it feeds the middle (wiper) of the 100Hz slide pot.
And look around the solder joints or IC U3 - pins 5-6-7 this drives the cap & slide pot, its one of the 8 Pin IC's.
Hope this all made some sense?
And that it helps you out.
PM me if you need the GE-7 schematic.
But it's relatively east to find it on the web.
Regards Dr. Bob
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Dave Simpson
Copper Member
USA
9 Posts |
Posted - 04/23/2007 : 14:10:40
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Thanks Dr. Bob!I'll check it out and see what I come up with.
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Dave Simpson
Copper Member
USA
9 Posts |
Posted - 04/25/2007 : 14:13:02
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Dr. Bob you are a genius! It was C10 that was the problem. Thanks to you it's working again. Cheers! |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 04/25/2007 : 14:49:23
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quote:
Originally posted by Dave Simpson
Dr. Bob you are a genius! It was C10 that was the problem. Thanks to you it's working again. Cheers!
Hi Dave Simpson & Guys
I'm glad you have it working
What did you find with C10, you didn't really explain, & it might help others, who read this thread, if they have the same, or a similar fault.
Why do you think it failed?
As I said, the Slide Pots in the GE-7 are pretty tough, as are most Boss pedals.
The most common thing that goes wrong on a GE-7, is the little white plastic caps on the sliders, goes missing.
The slide pots in the Beghringer graphic, are what I call skeleton pots, they are made without a protective metal housing.
Don't get me wrong, the Behringer, might be a cheaper pedal in all aspects, but it's a very quiet EQ.
I have one as a backup, & I sometimes use it pre. or post Distortion-overdrive pedal.
Regards Dr. Bob ..
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Dave Simpson
Copper Member
USA
9 Posts |
Posted - 04/26/2007 : 14:16:06
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One of the legs on the C10 capacitor was broken off. I just re-soldered the capacitor and it worked perfectly again. I would have never noticed it if I hadn't been checking the signal path part by part.
Thanks again for your help Dr. Bob! I was about to throw that pedal in the parts bin and buy another one to replace it. You saved me a little $$$ |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 04/26/2007 : 15:34:58
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quote:
Originally posted by Dave Simpson
One of the legs on the C10 capacitor was broken off. I just re-soldered the capacitor and it worked perfectly again. I would have never noticed it if I hadn't been checking the signal path part by part.
Thanks again for your help Dr. Bob! I was about to throw that pedal in the parts bin and buy another one to replace it. You saved me a little $$$
Hi Dave Simpson
Was the leg of C10, broken off on the component side, or on the solder side?
If it was on the component side, I guess there was just enough of the lead left, to warrant a repair.
Can I suggest, that you replace C10 with a new cap, it will make the pedal much more reliable.
How do you think the leg of C10, became broken, was it from a mod attempt, or some rough handling?
How long did it take you to find the fault?
Was it a MIJ, or a MIT, the newer MIT's have the low noise FET OpAmps.
I have an older, MIJ ACA, but I'm lucky, it's "not" noisy in my setup. 
Regards Dr. Bob .. |
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Dave Simpson
Copper Member
USA
9 Posts |
Posted - 04/27/2007 : 14:26:05
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It was on the component side so I was able to solder on a little piece of wire to the leg coming out of the capacitor. I'll try and track down a replacement capacitor at some point.
It's a MIJ GE-7, so I'm trying to keep it alive for a bit. As for the reason the leg broke, the screw that secures the two boards together had come loose and it seems the board was moving around inside the pedal. I would guess at some point the C10 capacitor bumped into something and snapped the leg off. The pedal is on my board and it's been on a few airplanes in the last few weeks. No telling how the baggage handlers were treating my pedalboard case. |
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GE-7 100 Hz slide isn't working
