Author Topic: Damaged cap?  (Read 773 times)

JoeR3155

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Damaged cap?
« on: December 01, 2019, 11:20:34 AM »
Noob question....
I melted the corner of the housing on a film cap while I was soldering a pot to a board. In situations like this, is there any way to judge if a film cap has been damaged and should be replaced?

Thanks

EBK

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Re: Damaged cap?
« Reply #1 on: December 01, 2019, 11:30:20 AM »
There's a 90% or more chance that your cap is still fine.  Generally, I'd say complete the build and see, unless the look of the cap bugs you.  Whether you can test it in circuit will depend on what it is connected to.

Care to share a pic?
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benny_profane

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Re: Damaged cap?
« Reply #2 on: December 01, 2019, 11:33:27 AM »
I was going to say the same thing. It can be unsightly, but still fine. If itís for yourself, Iíd agree with EBK (and a picture could help). Do you have a capacitor setting on your DMM or access to a components tester? If itís difficult to get to if you move forward with the build, or itís for someone else, I would personally just replace it if I had more in my stock.

JoeR3155

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Re: Damaged cap?
« Reply #3 on: December 01, 2019, 12:15:37 PM »
Thanks for the responses guys. The build is for me.

I do have a cap setting on my meter but wasnít sure if it would read correctly when the cap is soldered on the board. I guess I should try it if only for the learning experience.

Hereís a pic.
« Last Edit: December 01, 2019, 02:46:54 PM by JoeR3155 »

mjg

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Re: Damaged cap?
« Reply #4 on: December 01, 2019, 03:00:48 PM »
It looks like you've almost finished the build - I would just try it and see at this point.  There is a pretty low part count, so if it doesn't work, try to replace the capacitor.

But yeah, we've all melted a capacitor at one time or another, and it's usually no problem. 

JoeR3155

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Re: Damaged cap?
« Reply #5 on: December 01, 2019, 03:14:28 PM »
Thanks all for the guidance.  I'm lousy at de-soldering, and find it a little frustrating, or else I wouldn't hesitate to replace the cap.  Since it's accessible, I had already decided to keep going with the build, then go back and address the cap if it turned out to be a problem.

Well, I got it all wired and plugged it in and --- nothing.  I've got a long way to go to understand circuits, but based on the schematic (Aion Solaris Fuzz Face) I don't think the cap would lead to there being no sound at all.

I know the 'rock it before you box it' motto, but I've had good luck on the relatively few builds I've done up to this point.  I figured I'd keep building until I needed to make a test rig.  Well, I haven't found anything obviously wrong with the soldering or the wiring, so it appears beginners luck has run out and I'll be shifting gears to work on test fixtures.  I'm going to slog away at it, but might be posting here in a couple weeks looking for help!  ;)

Bio77

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Re: Damaged cap?
« Reply #6 on: December 01, 2019, 03:34:27 PM »
You might double check the build doc for the version you picked (the down side of "ultimate tweekability") .  Maybe the power is reversed or there is a NPN PNP mix up.  Does the LED light up?

JoeR3155

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Re: Damaged cap?
« Reply #7 on: December 01, 2019, 03:52:43 PM »
You might double check the build doc for the version you picked (the down side of "ultimate tweekability") .  Maybe the power is reversed or there is a NPN PNP mix up.  Does the LED light up?

Thanks. Thatís where I started, actually, checking power and confirming the configuration. I got a matched pair of PNP transistors from Small Bear. Iím using negative ground with the power inverter.

The LED does not light up.  I double checked the orientation.

benny_profane

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Re: Damaged cap?
« Reply #8 on: December 01, 2019, 04:33:46 PM »
That cap wonít have any bearing on the circuit working since itís just part of the Ďbodyí block. Start with the power (the ground wire looks like it could use more solder) and go from there. Are you getting good readings from the charge pump pins? Basically go from the power and ground connections and make sure that the circuit is getting voltage. Beyond that, ensure your transistors are oriented correctly. That wonít help with the LED not lighting, but should be a part of double-checking your work.

JoeR3155

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Re: Damaged cap?
« Reply #9 on: December 01, 2019, 04:53:11 PM »
....Start with the power (the ground wire looks like it could use more solder) and go from there. Are you getting good readings from the charge pump pins? Basically go from the power and ground connections and make sure that the circuit is getting voltage. .... That wonít help with the LED not lighting, but should be a part of double-checking your work.

Thanks very much.  I did touch up that ground wire after taking that pic, so that's not the issue.  I will follow the power and ground as you suggest.  Thanks again!

Bio77

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Re: Damaged cap?
« Reply #10 on: December 01, 2019, 05:49:02 PM »
I think the power is reversed, that's why no LED, but double check.  Since the power is going through a protection diode, I might suggest to try switching the leads,  but since you have some nice transistors you might want to wait for help from some of the fuzz jedis.  I'm not one, they actually give me a lot of trouble, even though they are simple.

alanp

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Re: Damaged cap?
« Reply #11 on: December 01, 2019, 10:27:49 PM »
Everyone has melted a box cap on a board by mistake. It's a rite of passage!
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JoeR3155

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Re: Damaged cap?
« Reply #12 on: March 31, 2020, 11:07:26 AM »
I figured Iíd give an update on this....
After getting nothing out of the pedal, I put this build aside back in December.  I did a few other builds, including making a test Rig, but this past weekend figured Iíd procrastinated long enough. I had disconnected the DC jack and unboxed the PCB. I connected the PCB to my test rig (built from the JMK PCB).  I got sound, but it was really lousy. My test rig is generating a lot of noise, which is another issue.  Figuring I couldnít quite trust the test rig, I threw it back in the box.  And it fired up straight away.

So maybe it really was a bad connection at the jack, even though I had touched up the joints before and it all looked good.

Bio77

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Re: Damaged cap?
« Reply #13 on: March 31, 2020, 03:41:38 PM »
Congrats!  Maybe it could have been a bad ground connection at your input jack.  It looks like you sanded the paint off, but maybe it wasn't making good contact.  When you disassembled/reassembled you might have fixed the problem. 

JoeR3155

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Re: Damaged cap?
« Reply #14 on: March 31, 2020, 03:45:38 PM »
Congrats!  Maybe it could have been a bad ground connection at your input jack.  It looks like you sanded the paint off, but maybe it wasn't making good contact.  When you disassembled/reassembled you might have fixed the problem.

Thanks for the help Bio!