[TenTec] 255 Power Supply

[Jim Anderson]

Is there a way to check the SCR? I pulled the board this morning and upon
closer inspection it is discolored at the base where the leads emerge.

I ordered a couple of the transistors from Mouser and will add the SCR to
the order.

Jim
K6JEA
On Sun, Mar 13, 2011 at 9:08 AM, Dr. Gerald N. Johnson
<geraldj at weather.net>wrote:

> The transistors are wired in parallel, but that 0 resistance from base
> to one of the connections is a shorted junction in one of them. There's
> no repair possible for the transistor, it must be replaced. When you
> take them out, you can tell which is bad, but a sturdy pair isn't a bad
> investment.
>
> .514 is about right for the forward drop of a silicon junction. OL is
> right for open. Which a junction should be one way. .000 for both
> polarities of the meter shows the shorted junction.
>
> 73, Jerry, K0CQ
>
> On 3/12/2011 10:23 PM, Jim Anderson wrote:
> > After searching Google on how to test a transistor I realized I was doing
> it
> > wrong.
> >
> > Here are the new readings...
> >
> > On the Diode function and the black lead on the base it reads .514 on one
> > terminal and .000 on the other
> > With the red lead on the base it reads OL on one terminal and .000 on the
> > other.
> > Both transistors give the same results.
> >
> > On the 2K ohm scale with the red lead on the base it reads 1.2 on one
> > terminal and .000 on the other
> > With the black lead on the base it reads 1.1 on one terminal and .000 on
> the
> > other.
> > Again, both transistors give the same results.
> >
> > Thanks for sticking with me on this.
> >
> > Jim
> >
> >
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>