[Amps] Ten Tec Titan 425 Fuses Blew

[Jim Brown]

More thoughts. I have three 425s, two of which are active in my SO2R 
contesting station.  It's not unusual for both fuses to flow due to 
spikes on the power line. It's also very common for both fuses to blow 
when there's nothing really wrong with the amp.  They don't blow often 
-- typically months apart, or even much longer intervals.

Several thoughts. Buy a bunch of 20A fuses from an industrial vendor. 
Also buy some 30A fuses.Most problems that blow fuses will blow both of 
them, because they are in series with the 240V line. If it's just a 
power line problem, or you're troubleshooting something other than the 
transformer, you can go through a lot of fuses before you nail the 
problem. I keep a 20A fuse on one side of the line and a 30A fuse on the 
other.  Saves a lot of fuses.

You can check for shorts in the tubes by pulling one or both of them and 
firing up the amp. The amp runs just fine on one tube, you just get less 
power out and the tuning changes slightly.

Like Bob says, work slowly and carefully around the HV.

One thing that causes fuses to blow is a short or an arc in the RF deck, 
and that can often fry one or two of the traces on a low voltage board 
in the power supply.  If things aren't firing up, you should inspect 
this. There are specific notes about this on the Titan 425 schematics on 
my website. http://audiosystemsgroup.com/publish.htm   The schematics 
come straight from the Ten Tec manual, but everything is shown on that 
same page, making it MUCH easier to trace and troubleshoot. Which is why 
I did it -- I was going nuts with those separate pages.

73, Jim K9YC

On 2/19/2013 12:03 PM, Bob Arenella wrote:
> Hi Mark,
>
>            I had one of these a while back....nice amp! If you short 
> pin 9 (Orange wire) and pin 2 (White/Black wire) you can energize the 
> p/s, if it has the cover attached.  The power supply has its own 
> saftey interlock.  BE CAREFUL!
>
>            If the problem is not in the P/S, remove the 3CX800's and 
> try to power up the amp (With the cover ON!). If that doesn't blow 
> fuses, try one tube at a time and see what happens.
>
>            If you're not comfortable working around high voltage, 
> DON'T MESS WITH IT, let someone with more experience check it out.
>
> 73 de bob
> n2oam
>
>
> ----- Original Message ----- From: "Mark Robinson" 
> <markrob at mindspring.com>
> To: <amps at contesting.com>
> Sent: Saturday, February 16, 2013 10:37 PM
> Subject: [Amps] Ten Tec Titan 425 Fuses Blew
>
>
>> Both the 20 amp fast blow 240v fuses just blew in my Ten Titan 425 
>> this evening while I was keying about 1200 watts on 160m. I am told 
>> that I can get Microwave 20 amp fuses from Home Depot.