Resistance in the PCB?

[BuddytheReow]

Hey All,

First time poster, here. Got a quick question regarding PCBs in general. I'm currently putting together a Hyped Fuzz and started with the resistors. The way I build is to test the resistance before and after soldering to make sure I didn't fry anything. I tested a 100k resistor before inserting and everything was good. After soldering I noticed the resistance dropped to ~47k. At first I thought it got fried by my soldering iron. I took it out, retested, and came back at 100k. I then tested the mounting holes themselves in the PCB and noticed it was coming up at 32k. Shouldn't the resistance be zero in the PCB? I checked a few other holes and mostly came back at zero with a few exceptions. Did I get a bad board?

Thanks

 

[Robert]

Have you already installed other resistors in the board? If so you're probably measuring those in parallel.

Post a pic.

 

[Betty Wont]

Testing before installation is sufficient. Resistors are hardy. Testing components in-circuit will give you the kind of results you are seeing.

 

[BuddytheReow]

I have. The multimeter is pointing to a 100k resistor, but showing up as 31k when tested (I reversed the numbers by accident above).

 

[rmfx]

You typically can't measure a resistor mounted on the board, if there are other resistors in parallel it's going to read lower. Testing the holes may also give a reading. Only way to measure a resistor on the board is to unsolder one leg and then measure.

That said, resistors are not very likely to fry unless you're reeeaaaally cooking them. I wouldn't worry about it. If the solder joints looks good then it's probably fine.

 

[BuddytheReow]

Thanks, everyone. I guess I’m being TOO careful doing this lol

 

[Betty Wont]

And desoldering can cause more harm than good. Don't sweat it. You are more likely to destroy the board with heat than most of the components. Be the most careful installing diodes, transistors, and ICs (SOCKET!!!).

 

[BuddytheReow]

And desoldering can cause more harm than good. Don't sweat it. You are more likely to destroy the board with heat than most of the components. Be the most careful installing diodes, transistors, and ICs (SOCKET!!!).

How would I know if I fried a diode?

 

[Betty Wont]

How would I know if I fried a diode?

The circuit won't work, or won't work correctly. None of us test components on the board unless troubleshooting. Don't worry about troubleshooting until you have trouble. Have fun and don't sweat each component. Just go for it. You aren't going to fry anything if you watch your time and temp. I've never knowingly lost a component to heat in my 25+years of this.

 

[BuddytheReow]

The circuit won't work, or won't work correctly. None of us test components on the board unless troubleshooting. Don't worry about troubleshooting until you have trouble. Have fun and don't sweat each component. Just go for it. You aren't going to fry anything if you watch your time and temp. I've never knowingly lost a component to heat in my 25+years of this.

What's a good temp to keep my iron at in general?

 

[Betty Wont]

What's a good temp to keep my iron at in general?

I run mine at about 350 c. .040 diameter 60/40 solder. No more than 3 seconds. If you need to rework a spot, let it cool first.

 

[zgrav]

I keep my iron around 310 c. for parts on a pcb using 67/33 solder.

 

[benny_profane]

I run my iron at 350C (with a chisel tip) and use 63/37 0.8mm solder.