Microscopic electronic repair. How to?

[bwringer]

You're gonna be SO mad if that part is just a jumper...

I once went through all sorts of convolutions to figure out a teensy (but not as teensy as this) resistor's value only to find it was "0"; a jumper packaged like a resistor for the sake of convenience. Or maybe there was a different version of the circuit out there that used a resistor.

 

[zendriver]

A component that small, are you sure it's even soldered?

https://www.gluespec.com/blog/electronic-component-adhesives-guide

 

[Grant Gunderson]

Ordered this digital microscope

Could use some recommendations for some high quality extra small tweezers.

 

[iron block]

Erem tweezers are pretty good. Zoro has them

 

[LXCam]

Ordered this digital microscope

Could use some recommendations for some high quality extra small tweezers.

I had no idea something like that was at that kind of price range. As much as it despises me to buy from Amazon I gotta have one. I’m not working with your level of micro components, but I do a lot of forensics with my phone utilizing macro pics. That’d be far better.

 

[djbmw]

Ordered this digital microscope

Could use some recommendations for some high quality extra small tweezers.

Congrats! You'll be happy with it! One of the youtubers I subscribe to did a decent review of it as well (Joyalens and Andonstar badge the same unit as their own):

 

[Max]

Those "microscopes" are, unfortunately, no good. I bought one of those a few years back and it's dollar store quality with horrific resolution. The lense also needs to be pressed up to the componemt to see.

The Andonstar AD246S and equivalent scopes are good. I personally have the JOYALENS JL249MS.

Damn GJ is costing me money again. Thank you.

 

[Max]

Damn GJ is costing me money again. Thank you.

In for a penny, in for a pound - I also ordered a Hakko desolderer and solder station. I decided that my 55 year old Heathkit soldering station should be upgraded.

 

[Grant Gunderson]

Damn GJ is costing me money again. Thank you.

In for a penny, in for a pound - I also ordered a Hakoo desolderer and solder station. I decided that my 55 year old Heathkit soldering station should be upgraded.

Haha. In for a penny, in for a few grand is more like it! That HAKKO gun has made a task I used to dread actually enjoyable. I won’t say this site has cost me a small fortune over the years…. It’s more like a very large fortune. However having the proper tools and more importantly learning the proper techniques here is priceless.

 

[djbmw]

As luck would have it,... the control board on my stove/oven crapped out and wouldn't kick the oven element on. Turns out my lower element failed (was slowly failing over the past few weeks, and then finally blew up), which caused more current load to pass through the lower element relay (causing it to arc more than it should), and when the heating element blew it sent back voltage through one of the SOT-23 diodes. I had to order a new relay, but already had the diodes. Overall it took ~ 1.5 hours to tear apart the oven, troubleshoot, order the new relay, repair the board (I used a solder sucker on the relay and hot air on the diode to remove), and re-assemble the oven - Just in time for Xmas!

Bad Relay & Burnt Diode



Burnt Diode Under Microscope (SOT-23 (BAV70 A4)



Diode Removed


Bad Relay & New Relay(s) - I only need one (for now)


New Diode Soldered In

 

[larry4406]

As luck would have it,... the control board on my stove/oven crapped out and wouldn't kick the oven element on. Turns out my lower element failed (was slowly failing over the past few weeks, and then finally blew up), which caused more current load to pass through the lower element relay (causing it to arc more than it should), and when the heating element blew it sent back voltage through one of the SOT-23 diodes. I had to order a new relay, but already had the diodes. Overall it took ~ 1.5 hours to tear apart the oven, troubleshoot, order the new relay, repair the board (I used a solder sucker on the relay and hot air on the diode to remove), and re-assemble the oven - Just in time for Xmas!

Bad Relay & Burnt Diode



Burnt Diode Under Microscope (SOT-23 (BAV70 A4)



Diode Removed


Bad Relay & New Relay(s) - I only need one (for now)


New Diode Soldered In

Impressive!

 

[Kent_B]

Nice job. I used to do that stuff for a living.

 

[powertrip]

That's a chip resistor. I work on this scale of stuff daily building sensors. I use a Hakko fx-951, T15-D08 tip and a lot of experience.

 

[djbmw]

That's a chip resistor. I work on this scale of stuff daily building sensors. I use a Hakko fx-951, T15-D08 tip and a lot of experience.

Are you referring to my repair? Its not a resistor - its a high-speed switching double diode (SOT-23 (BAV70 A4)).

OP's component, however, might indeed be a chip resistor - its hard to tell from the photo.

 

[Grant Gunderson]

Electronic microscope arrived. See fluke test lead for scale. I need some much smaller probs. Any recommendations?
BTW that component reads .2Ω on a good board. Any idea what to order for a replacement? I should preface this, that I dont know **** about working on PCB's but Im willing to invest in the equipment and learn.



Same board for scale. This wireless transmits power / reads the torque sensors and Hall effect sensors off of a e-bike motor.


This is another bad board. It's obviously missing a component and another is dislodged.

This is a known good board out of another motor.
Any idea what these components are?

The larger black one thats completely missing off of the board above reads 1MΩ on the good board
The grey component reads .9KΩ


These may be way too small in reality to fix, but there is ZERO parts or support from the MFG and I get a lot of these motors in with the same issues. Worst case scenario, is that I am improving my skills at diagnosing the issues, so willing to invest some resources and time in trying to repair them.

 

[djbmw]

The scope images look nice! There's writing on the face of the component (the one i've identified as a possible diode below ) that you should be able to see if you move the lights around, and/or focus the lens differently. It can also help to use a Q-tip with rubbing alcohol on it to clean off the component. You might also need to swap lenses or lower the scope closer to the board. At first glance, here's what the components appear to be:

 

[ATW]

Grant, sometimes a degree of caution needs to be applied when measuring components "in circuit", the surrounding circuit may be a more significant (higher or lower value depending on configuration series/parallel) than the component you think you are measuring.

Take the 0.2R - in IMG_7420 the copper pour/plane(s) that it is bridging appears to go fully around the center cut out of the board (at the 2 o'clock it gets a bit thin, maybe changes to other side or inner layer). If this is the case probing both ends of the component you will be measuring the resistance of the plane/pour.

The "grey" component, most likely a capacitor, if measured in circuit using Ohms scale of multimeter, you are most likely measuring the resistor next to it. To get an accurate reading of that possibly remove the good one and measure on capacitance scale of multimeter.

Andy

 

[djbmw]

Grant, sometimes a degree of caution needs to be applied when measuring components "in circuit", the surrounding circuit may be a more significant (higher or lower value depending on configuration series/parallel) than the component you think you are measuring.

Take the 0.2R - in IMG_7420 the copper pour/plane(s) that it is bridging appears to go fully around the center cut out of the board (at the 2 o'clock it gets a bit thin, maybe changes to other side or inner layer). If this is the case probing both ends of the component you will be measuring the resistance of the plane/pour.

The "grey" component, most likely a capacitor, if measured in circuit using Ohms scale of multimeter, you are most likely measuring the resistor next to it. To get an accurate reading of that possibly remove the good one and measure on capacitance scale of multimeter.

Andy

100%!
And, to make life easier, taking components this small "out of circuit" just means unsoldering one leg and slightly raising or moving it so that its not contacting the pad/trace. This way its still attached to the board with the other leg and you dont lose it, but it's electronically out of circuit.

ESR Capacitance meters (in circuit) are decent on larger components but struggle on stuff this small - just lift a leg, measure with your multimiter, and solder it back in place.

 

[djbmw]

I need some much smaller probs. Any recommendations?

Hi Grant - I forgot to reply to this question. I have a variety of leads but my go-to are cheapies from Amazon, made by Bionso. They are silicone leads and the probes are interchangeable. The probes I use for this type of work are the 1mm sized ones. Here's a link to the current Amazon listing: https://www.amazon.ca/dp/B0CXQNVRJG

And here's a few comparison pictures of the 1mm vs 2mm probes:

 

[Grant Gunderson]

Hi Grant - I forgot to reply to this question. I have a variety of leads but my go-to are cheapies from Amazon, made by Bionso. They are silicone leads and the probes are interchangeable. The probes I use for this type of work are the 1mm sized ones. Here's a link to the current Amazon listing: https://www.amazon.ca/dp/B0CXQNVRJG

And here's a few comparison pictures of the 1mm vs 2mm probes:

Thanks! I ordered those along with some metering tweezers as well as a set of HAKKO hot tweezers.

I still need to see if I can read the numbers off of those components. Will be a project once things settle after the holidays and the kids are back in school.