5. Finding Parts

Troubleshooting a Dranets 4400 power meter, late Friday night. Need one for an order Monday. They sell used for about $9000. Dranetz is very secretive and there is no repair data available. This one is completely dead. Open it up, test the power switch, checks ok. Noticed a semiconductor, blown up. Brown stuff all over the board. I suspect it is a diode because it is numbered with a “CR” designator. But probably not an ordinary rectifier because this thing is powered by a DC power supply. So, what is it? Took one from another broken unit thinking I can order a replacement later. It worked, now I have one good power meter for the order Monday. Still have to order one to restore the other unit.


Printed on the part is the following: A logo “ST”, a three letter code “BBE” and another code below that, C330. So how do I order a new one and what is it?


If the search terms “ST BBE” are input to the search engine there are a couple of data sheet sites that come up with something close to the answer. But to see the data sheet a fee must be paid. In the returned text from the search engine there is a part number that may be close “SMBJ20A-TR”. Going to digikey and putting in this number results in a dead end, nothing found. Try aother way.


The “ST” logo stands for ST microelectronics. Hopefully your experience will help with logo identification. I used to have a catalog, Jameco I think, had all the logos on the cover.


Anyway, using Google it is easy to find the ST website. Putting in the search box “marking BBE” takes me right to a pdf data sheet that gives me the correct part number “SMBJ12CA-TR” as crossed to the marking BBE in table 5 on the data sheet. Checking Mouser, I find it available for about 0.50 ea, minimum quantity one. Now, anytime I can fix a $9000 piece of gear for 50 cents and a couple hours labor it is a good day.


Now the sanity check. This device, according to the data sheet is a protective device that will self destruct to protect the gear if the supply voltage spikes over 12 volts. It is a surface mount component the same physical size as the one I removed and measured with a caliper. This all makes sense as the supply is in fact 12 volts. It is just downstream from the power switch. My confidence is high that I have the correct part.

The process is:

  • Look for id on the part, logo, part number, date code.
  • Search on that information.
  • If needed go to the makers website and search the numbers or codes.
  • Finally search the electronic component sites for a replacement part.  See the page on parts links.


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