Measuring resistors once installed?

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CapnCrunch
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Measuring resistors once installed?

Post by CapnCrunch »

Is it possible to measure resistance once your resistors are soldered into your board? I'm having issues with a build I recently completed. It "works", but it lacks volume and the sound is thin. It also breaks up in a very "non-musical" way.

I clipped my meter onto a few of the resistors, and am getting some whacky values. A few read as correct, but others are way off. The ones that read as correct are the resistors that are paired with a cap, and there are no other resistors sharing a solder point on either end.

I was kind of afraid I may have damaged one or two in the soldering process.
Firestorm
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Re: Measuring resistors once installed?

Post by Firestorm »

It's really hard to damage a resistor through soldering (unless you used an 85-watt iron). They are designed to dissipate heat; I'd look elsewhere for the problem. Yeah, some resistors can't be measured in circuit because they'll interact with other resistances and give a reading of the whole part of the circuit they're connected to.
tubeswell
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Re: Measuring resistors once installed?

Post by tubeswell »

Yup - in most cases you only get reliable measurements before you connect them up. CCs can overcook more easily than other types
CapnCrunch
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Re: Measuring resistors once installed?

Post by CapnCrunch »

These are carbon comps. A couple of points have like three resistors and and a couple jumpers in a single eyelet, so the iron had to sit longer then usual to get everything hot enough to solder....... those are the ones I'm most worried about.
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Structo
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Re: Measuring resistors once installed?

Post by Structo »

IF when you pull the tubes and there is a resistor that connects to a tube pin, you should be able to measure it's resistance if one end is not connected.
Tom

Don't let that smoke out!
Firestorm
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Location: Connecticut

Re: Measuring resistors once installed?

Post by Firestorm »

Maybe you have the opposite problem: the joint didn't get hot enough to make a good electrical connection. Cold solder joints can exhibit the symptoms you describe. Check all the key voltages; that is likely to show a bad joint or a bad resistor (except at AC-only points in the circuit).
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Cygnus X1
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Re: Measuring resistors once installed?

Post by Cygnus X1 »

CC's will usually bubble a bit right at the point of giving up the magic smoke.

I'd (carefully!!!) go through and check the voltages
on the pins and other points before ripping anything apart.

Also first check for bonehead gremlins.

They sneak in at night and mess up values, tie points, etc.
I get those once in a while.

:)
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