Re: Help with Thunderclock parts ID

[Michael J. Mahon <mjmahon@aol.com>]

"Apple2Steward" <none@none.net> wrote:
> To my horror, I found that my Thunderclock had developed 
> corrosion on the legs of several semiconductors, one of which had 
> corroded through.
> 
> I'm having a trouble identifying a few components for replacement 
> and wonder if anyone who is well-versed in such things could 
> help.
> 
> A D1 there is a diode that has lost its painted-on markings.  It 
> is next to R10, a 10% tol. resistor which has (reading from the 
> other end) gray - red - black bands (82 ohms?).
> 
> The worst transistor at Q3 is marked:
> 
> F2N
> 3904
> EBC
> 
> The other at Q4 is marked:
> 
> ~202/
> 2N
> 3904
> 
> (The "~" is actually the two National Semiconductor squiggles one 
> above the other).
> 
> Am I correct that the two transistors are the same:  2N3904, just 
> from different manufacturers (Fairchild and National?)?
> 
> What would be a likely replacement for the diode?  Would it be 
> necessary to ID it from another Thunderclock or could I meter it?
> 
> Any suggestions would be appreciated!!

As noted, it's an 82 ohm resistor and they are both standard 2N3904's. 
Any standard diode--like a 1N914, for example--will work.  It only
conducts a few milliamps and blocks a few volts.   (It's part of the
charging circuit.)

-michael  -  NadaNet 3.1:  http://home.comcast.net/~mjmahon