Here's what happened-

I ordered 8 cheap panel meters from China to measure DC v. Three of them work fine but the other 5 are configured for something else on the board (I think AC v). Anyway, Instead of mailing these stupid meters all the way back to China, I think it would be easier to convert the board to measure DC v myself.

So, what I did is compare one of the working meters to the non-working meters and started resoldering, etc. to make the boards match up.

The boards that are not working are missing some parts that the boards that DO work have, and I can not identify 2 of them.

One of them is shaped like a half circle with 3 leads coming off. The board labels each lead as "E", "C" and "B" and the part is labled "3198".

The other part looks like a somewhat larger resistor and the board labels it as "22mH".

Here are the pictures:

This first picture is of the 2 parts that are missing on the non-working boards.

And here is the picture of how the board labels these parts on the boards where they are missing:

I'm sure some of you could identify these from a mile away.... I'm just not sure what they are so I can go and order them myself and *hopefully* get these things working!

 

The part on the left is a 22μH Inductor and the part on the right is a 2N3198 transistor.

 

The inductor is correct, but it's a stretch to identifying the transistor. A 2N3198 is a 75 watt transistor, which is hard to get in TO-92.

The transistor is going to have a prefix of something like 2SC or 2SD. The 2SC3198 is somewhat likely, as it is a switch and comes in TO-92.

 

Thanks for the help! Got to love these forums! I knew someone would be able to spot them right off the bat...

Thanks again guys, I'll go ahead and order these parts and see what happens.

 

It looks like it's labeled 22 millihenries, not 22 microhenries. That seems a more likely value for a switching circuit.

Jack

 

Could the transistor be a KTC3198 which is an NPN transistor for general purpose and switching applications ?

 

Any TO-92 transistor with those 4 digits might be the one. A 2N2222 might work fine, for that matter. Any NPN switch will probably work. Part of the fun of guesswork.

 

Geez... I can't find anyone selling a 2SC3198, 2SD3198 or even a KTC3198 ANYWHERE! I checked out Mouser, Digikey, Newark and more...

Anyone have any suggestions?

 

Probably any NPN. Try a 2N3904. Watch out for the pin labeling. Some transistors are different.

Jack