[TenTec] 255 Power Supply

[Jim Anderson]

With the meter on Diode I get .513 in one direction and Open in the other.
If I set the meter on the 2K ohm scale I get 1.18 but when I reverse the
leads I get 1.2. Both transistors read the same.

Jim

On Sat, Mar 12, 2011 at 7:20 PM, Dr. Gerald N. Johnson
<geraldj at weather.net>wrote:

> Check the paralleled transistor junctions with an ohmmeter. The should
> be a difference in directions and not zero ohms. The symptoms are that
> the junction in at least one of the transistors is melted and so shorted.
>
> And it might be that the crowbar SCR has shorted.
>
> 73, Jerry, K0CQ
>
> On 3/12/2011 9:11 PM, Jim Anderson wrote:
> > Thanks, I have done a bit more digging since I posted.
> >
> > If I pull the wire that leads from the diode bridge to the board with the
> > pass transistors no fuse blows. If I pull the internal 20 amp fuse and
> turn
> > it on the AC fuse is OK. If I disconnect the three wire plug that leads
> from
> > the transistor board to the regulator board it wants to blow the AC fuse.
> > So, as Al said, it seems to be an issue with that board. Is there a way
> to
> > check the transistors with them mounted or should I just assume it is one
> of
> > them and order a couple of replacements.
> >
> > Thanks.
> > Jim
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