Testing in and out of circuit

Jtoney

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I have a question on what components can be tested in circuit and what has to be taken off of the board to be tested. I've got my multimeter and I've got some other meters to check transistors resistors and stuff but I don't have that question. That's something that I can't seem to find the answer for.

I'd appreciate if you can help me with this or even send me to a video that explains it or what have you. Thanks
 
You just need to redirect your laziness like I do. I'm lazy and don't want to do it again so I do it good enough. Seems to be working pretty well. Best way to determine if something can be tested in circuit is to learn how the electronics work, there is no guide to what can and what can't because that changes depending on everything around the component you're eyeballing.
 
Totally agree with above statements. Many things on a g07 for example I test in circuit, based on hundreds and hundreds of repairs. I learned to recognize which parts show bad when tested in circuit, and which do not.

THere is no set rule............Unless you want to go by the rule, pull everything for testing. :)
 
You underestimate my laziness


This might not be the hobby for you in that case. Electronics repair is a skill, and you get better by continuously learning and practicing. Think of it like learning to play a musical instrument. You can't watch a 2-minute video and be an expert. It's a slow process you build over time.


The answer to your question is it depends.

Most things can be tested in-circuit, when you know what you're doing. Especially if you have a second known-good copy of the board you are testing. Many components will test the same in or out of circuit, however it depends on the circuit. So there are no hard and fast rules.

Some circuits will affect what a component value is reported as when tested in-circuit (even for something as simple as a resistor). But if you have access to a second known-good board, you can A/B compare the two, and should see the same error between boards.

There are other cases where if you test something like a resistor and you get infinite resistance, or you test a transistor and get opens in all directions, you can be almost certain the part is bad (but you should still pull and check it anyway if you aren't 100% sure). So it depends on many factors.

Beyond that, the answer isn't simple. I've written more about this in other threads. Here are a couple of posts in threads with related info:





Here's a set of search results to other related threads where I've mentioned in-circuit testing, many of which should have additional tips. Feel free to comb through them. The more you read, the more you'll learn:

 
I came up the hard way using a Radio Shack soldering iron and a Radio Shack desolder bulb. when I was in my 20s I didn't really have limits on what I would muck with in the interest of fixing things. when I reached my 30s is when I started to formulate the process of trying to understand what I'm doing and why I'm doing it. in my 40s I have a wealth of experience lodged in my head and I usually know the right time and place for when and what to execute. now I have limits, I stick to what I know because it's actually more cost effective to pay someone else that knows what they're doing thoroughly to do it instead. I still take my job serious, but not to the point where I get stressed out. out of 1000 things I know how to do 997 of them. most people will appreciate the fact I know 997 things. then there's other people that want to knock me for not knowing how to do the other 3 things.

after telling you my partial life story about being a game technician, I would like to direct attention to one @SCUBA King. I nurtured that lad years ago with my wisdom and turned him into a monster. he doesn't have limits. he just mucks with virtually everything and keeps fighting until he wins. he's my finest creation.

now I'll impart some wisdom in you. people are baffled when I tell them I wasn't formally educated in the art of fixing video games, monitors, pinball, and whatever else. I tell them "I learned by doing it", because I was placed in the unfortunate position that making 1/4 minimum wage in my family's business, I dedicated myself to making all games work at all times. so I got into virtually everything, there were many more wins than there were losses. and the losses I went back and kept fighting until I won. I did my K7000 videos the other day, I don't remember if I mentioned it (cause the whole routine was adlibbed as I always do it) but I learned how to read schematics working on K7000s. I also watched almost all the Randy Fromm's Arcade School DVDs. which he has posted a lot of that material on his YouTube channel: https://www.youtube.com/@randyfromm

if you care enough you will want to amass all the knowledge you can. I'm not a scholar in electronics theory, but I would encourage you start there on Randy Fromm's channel. I don't use much of it in real world applications, so my brain interprets it as a place I can save some disk space by not dwelling on it. LOL

I hope this was helpful. I'll probably hate myself and want to delete this post later.
 
Especially if you have a second known-good copy of the board you are testing. Many components will test the same in or out of circuit, however it depends on the circuit. So there are no hard and fast rules.

Some circuits will affect what a component value is reported as when tested in-circuit (even for something as simple as a resistor). But if you have access to a second known-good board, you can A/B compare the two, and should see the same error between boards.
This strategy is extremely helpful in troubleshooting. Not always available but boy its nice when it is.
 
I came up the hard way using a Radio Shack soldering iron and a Radio Shack desolder bulb. when I was in my 20s I didn't really have limits on what I would muck with in the interest of fixing things. when I reached my 30s is when I started to formulate the process of trying to understand what I'm doing and why I'm doing it. in my 40s I have a wealth of experience lodged in my head and I usually know the right time and place for when and what to execute. now I have limits, I stick to what I know because it's actually more cost effective to pay someone else that knows what they're doing thoroughly to do it instead. I still take my job serious, but not to the point where I get stressed out. out of 1000 things I know how to do 997 of them. most people will appreciate the fact I know 997 things. then there's other people that want to knock me for not knowing how to do the other 3 things.

after telling you my partial life story about being a game technician, I would like to direct attention to one @SCUBA King. I nurtured that lad years ago with my wisdom and turned him into a monster. he doesn't have limits. he just mucks with virtually everything and keeps fighting until he wins. he's my finest creation.

now I'll impart some wisdom in you. people are baffled when I tell them I wasn't formally educated in the art of fixing video games, monitors, pinball, and whatever else. I tell them "I learned by doing it", because I was placed in the unfortunate position that making 1/4 minimum wage in my family's business, I dedicated myself to making all games work at all times. so I got into virtually everything, there were many more wins than there were losses. and the losses I went back and kept fighting until I won. I did my K7000 videos the other day, I don't remember if I mentioned it (cause the whole routine was adlibbed as I always do it) but I learned how to read schematics working on K7000s. I also watched almost all the Randy Fromm's Arcade School DVDs. which he has posted a lot of that material on his YouTube channel: https://www.youtube.com/@randyfromm

if you care enough you will want to amass all the knowledge you can. I'm not a scholar in electronics theory, but I would encourage you start there on Randy Fromm's channel. I don't use much of it in real world applications, so my brain interprets it as a place I can save some disk space by not dwelling on it. LOL

I hope this was helpful. I'll probably hate myself and want to delete this post later.

I read the first paragraph of that and heard a film narrator's voice in my head…
 
Being lazy is ironic in this hobby. Lazy troubleshooting involves pulling and shotgunning parts which can introduce more problems. Effective troubleshooting usually leads to less work but you have to upfront the learning.

To answer the original question: in circuit vs out of circuit troubleshooting is just dependent of what you need to know and the type of circuit. Sometimes things can interact with each other in ways that can effect the output (such as multiple devices sharing the same output). It also really depends on what tools you have at your disposal as well. 75% to 95% of the time I test in circuit.

Ultimately if you are unsure just pose the question here with as much context as you can give. There are people on this site who have lots of knowledge who are happy to share it.
 
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