Ken,
I’ve got a homebrew HiPot tester, if you think it could help.
Steve
Sent from my iPhone
> On Jun 6, 2025, at 4:56 PM, Ken Claerbout <kenk4zw@gmail.com> wrote:
>
> I've been trying to repair a Ten Tec Titan Model 425 amp and I'm about out
> of ideas. Here's where I'm at.
>
> The Soft Start 1.5 amp fuse blows.
>
> This model power supply has the separate rectifier and filter board,
> mounted on top. The soft-start and bias circuitry are on the lower board.
> With the rectifier/filter board disconnected, the fuse does not blow. I
> have the gray cable connected between the PS and RF deck but not the HV
> cable. Anytime I connect the rectifier/filter board the soft start fuse
> blows instantly. Seems simple enough. Most likely something on that
> board, bad cap, diode, the usual suspects. Nope! Everything checked OK.
> But NR4M had new caps from a project he did so I "borrowed" eight of those
> and replaced the caps. Still blows. Replaced diodes and resistors. Same
> thing, fuse blows. Everything on the board has been replaced at
> this point. I don't see any burned traces on the board, like what happens
> sometimes.
>
> I pulled the lower board and looked it over. I don't see anything wrong
> with it either. I don't see any DC shorts on the transformer. I've had a
> few of those go bad in the past. They take out the 20 amp line fueses and
> I can measure the short. So to recap
> 1. The soft start fuse is blowing
> 2. It doesn't blow with the rectifier/filter board disconnected
> 3. All components have been replaced on the rectifier/filter board.
>
> What am I missing??
>
> 73
> Ken K4ZW
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