[TenTec] Titan 425 shelved for 10 years

[Jim Brown K9YC]

On Mon, 18 Feb 2008 22:10:47 -0500, DC wrote:

>How good is the final tube in a Titan 425 thats been un-used for 
>ten years?

I agree with Bob that the most likely problem purely from sitting 
is the lytics in the power supply. I would turn it on as Bob 
suggested, letting the caps reform if they're going to. Chances 
are at least some will be bad. But they may not blow -- they may 
simply open, and that will show up as reduced plate voltage UNDER 
LOAD, but not without a load. And you'll get reports of 
hum/buzz/nasty CW note. 

If that happens, kill the power and let the HV discharge for a 
long time. Yes, there's safety protection, but when that safety 
protection discharges the HV it can start blowing out transistors 
and even melting a trace on the PS rectifier board!  

To check the caps, use a traditional VOM like a Simpson 260 on its 
medium R scale. Check the R in one direction, leaving the probes 
in place long enough for the VOM to charge the caps, then reverse 
the probes. A GOOD cap will show strong charge and discharge 
current (low resistance) in both directions. A BAD cap will show 
much less. Measure them all and you'll get a fell for what normal 
is. Replace only those that check bad, then fire it up and repeat 
the process. Chances are if one is bad another will be. 

BTW -- there is a detailed pdf of the schematic of the Titan 425 
on my website. http://audiosystemsgroup.com/publish  It shows 
everything but the RF (which is by far the simplest part). 

73,

Jim K9YC