[Amps] Ten Tec Titan Troubleshooting Frustration

[Alek Petkovic]

G'day Ken.

It has to be the transformer. It is only when you connect the 
rectifier/filter assembly that the fault occurs because that is somehow 
providing a return path to the faulty burnt through windings.

I have a transformer removed from a friend's Alpha 91B amplifier here 
that caused similar symptoms. Run it by itself and everything runs 
sweet. Connect everything up and all hell breaks loose. Apparently that 
was a common problem with that amplifier.

It is insulation breakdown or burn through between windings in your 
transformer. Disconnect everything from the transformer and check with a 
megger, every wire to every other wire.

Good luck, Alek VK6APK.

On 7/06/2025 4:55 am, Ken Claerbout 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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