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Multimeter DIY Repair? Answered

I have a Radio Shack digital multimeter, Model 22-174. Since the 10 Amp measurement circuit is not fused I blew this circuit and that part of the meter does not work now. I like this meter and would like to know if I can DIY repair it and what I need to do. I have looked around the Internet and have not found any information including the Radio Shack site. Was looking for the wiring diagram only found a parts list. I hope that I can fix it. If I can fix it I will fuse the test leads (black lead) or work out an internal fuse for this circuit so I don't repeat my mistake. Any help would be nice. Thank you.


I have one of these multimeters too, and popped it while trying to do some current measurements... I was WAY too tired at the time, and I knew what I'd screwed up once the deed was done... ;_;

Same boat, I have a large resistor, charred. It's raised from the board a bit. I don't know the value due to the blackening or if there is other damage though. I do NOT recommend any meter from Harbor Freight, unless you really are looking to scrape the bottom of the barrel. The quality is... low...

While Radio Shack meters aren't exactly the highest end meters ever, they do the job, and some models do the job quite well! Infact, I already replaced my old Radio Shack 22-174 meter with a newer Radio Shack model, and I'd personally consider a Vichy, Brymen, Exetech, BK Precision, or Uni-T... or you could get a Fluke... but you better be prepared to open your wallet for that. Fluke is over priced for most hobbyists.

What I REALLY miss about my 22-174, that I have NEVER seen in any other model of meter, is the 3 wire automatic transistor tester. You didn't need to know the emitter, base, and collector, nor the type of transistor. You just plugged it in in any direction, and it told you on the screen. It was nice for confirming leads before soldering.

Anyone ever see a meter with that feature, or maybe know a DIY tester that can do it (something using an arduino, maybe)?

It's a good multimeter, and even though you can replace it quite easily with a cheaper one, I really don't want to. My problem is a bad 1 watt resistor that sits up off the pc board a bit. It's blackened so I can't tell the value of it. My guess is that it is rather low but I really don't know. In fact I don't exactly know what happened to it, as when I left it was fine, I came back the following day and it didn't work.

Tell me where exactly it is and I will give you the value off my meter.

above title and link for manual and part list.
My meter 22-174B is stuck in overrange (display) since I replaced a fuse. I can't get it to read anything. Looking for Ideas.


8 years ago

Found this on internet.  Credit to Electronics-diy.com. 
May be not exactly like yours meter.
Hope this schemetic diagram can help you to trace the faulty part


USUALLY, these things have a fusible shunt on the PCB, which will have burned out. Its often WWWWWWW shaped,

Sometimes the current measuring shunt is a piece of wire (of some kind) that jumps off the board for a few cm, then jumps back.  Some pictures of this are attached.


Thanks for the pictures, my shunt is intact. No burnt circuit paths, no odd smells. I really think I need a road map of the circuit to figure this one out. All surface tech parts and a main processor chip. If I don't get it fix no big deal.

You likely blew the internal fuse usually located next to the battery.  New users of multimeters are unsure of where the probes go since there are 3 "holes" and only 2 probes.  NEVER place any probe in the AMPS jack unless you are VERY carefull and you know what you are doing.  Because...  if your probe is in the AMPS jack and you plug meter to anything, you will either damage your meter, or the device you are testing.  The AMPS- setting places a direct short across whatever you are testing.  If you keep your meter set to VOLTS or OHMS and keep probes out of the AMPS jack... then you will not have this problem.  If you cant fix your meter, consider going to harbor freight tools. You can buy a cheapy meter for about 2 or 3 dollars.  They are decent meters too!

You'll have to open it up and see if you can find out which part or parts have gone bad.

Look and smell for any burned parts.  If the meter still works on ohms of voltage then the meter is not burned out.  Look at the pcb traces, resistors, switch legs etc.

If it's digital then you're going to have to be really lucky if you're going to be able to repair it.

Use another meter on resistance to check that the resistors and diodes are still good.

Even if you can't fix it, it is still good experience to try.

Good luck.

Thanks, I sure wish I had a wiring diagram, or know someone else that had to do the same repair and what they replaced.