***** 3 pin TO126, device marked S2003

and

Probably a 5V, 10W (with heatsink) zener diode

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Diverse Devices, Southampton, England 
electronic hints and repair briefs , schematics/manuals list on 

On Sat, 15 Mar 2008 10:41:47 -0000, "N Cook" put finger to keyboard and composed:

It would help to know where in the circuit it is located and to which components it is connected. If it is connected across the incoming supply (from a DC power pack?) then it could be a transient voltage suppressor, and/or a reverse polarity protection diode. The numbers would suggest that it may be a 20A (?), 2A, 3A, 30A, 30V, 20V (?),

200V (?) part. The "S" may suggest Schottky, although that would be unusual in a linear PS.

FWIW, Teccor makes an S2003L 3A 200V SCR in a TO-220AB package, but I would think that it would be useless without all three pins. Otherwise it could have been used for overvoltage crowbar protection.

It may help to put a photo on your web site.

- Franc Zabkar

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diode

It was just one of those things in passing. Inspecting the ps and pa boards for any other potential problems, came in due to failing contacts on the headphone socket, left speaker cutting out.

If I find something like that , unfamiliar or odd, and googling fails to elucidate, I try and find out what it is. All elese functioning perfectly, but seemed odd using 2 of 3 pins. A nice stable 5V over the 2 pins in the ps area, so that was my assessment. No heatsink used on this one but a useful TO126 format for say 10W zeners that are bolt-downable

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Diverse Devices, Southampton, England 
electronic hints and repair briefs , schematics/manuals list on