[Amps] Titan 425 will not turn on

[Jim Brown]

That's right, Joe -- the Molex connector must be fully inserted and 
inserted correctly. Like most Molex, I don't think it's possible to 
insert it wrong.

I just looked at the schematic to refresh my memory.  That 
multi-conductor cable carries the power interlock, filaments, the 28V DC 
supply, and 120VAC to run the fan. Check my schematic. The interlock 
goes through a micro-switch under the cover of the PSU and another under 
the rear cover of the RF deck.

See my notes on the schematic about failures that can fry traces in the 
28VDC section of the power supply. Also, there's a 4A slow blow in the 
surge protect circuit. It's inside the PSU. And there's a 1 ohm resistor 
in series with the 28VDC line that serves as a fuse for the 28V bus.

I have three vintages of 425s here. All have the main power switch on 
the RF deck (it's the bottom switch).

My schematic does NOT include details of the RF circuitry around the 
tubes (LPF at input, and the tank circuit), and there are variations 
from one vintage to another.

http://k9yc.com/Titan.pdf

73, Jim K9YC

On Tue,10/25/2016 11:49 AM, Joe Giacobello, K2XX wrote:
> I've sold my Titans, but besides the HV cable you need the low voltage 
> cable between the P/S and RF deck.  IIRC, the power switching is done 
> through that cable.  (Make sure the green dot faces up when you plug 
> the cable into the Molex socket.)  Also, IIRC, there is a power switch 
> on the P/S together with voltage selector and fan speed switches.  
> Some of the earlier units may not have had the voltage selector or fan 
> speed switches.