[WRL] Globe Scoute Model 680 resistor overheating problem

[Joel Gonzalez]

Hello group,

I recently purchased a WRL Globe Scout Model 680. I have not attempted to
transmit on this radio yet; I have just turned it on in standby mode. When I
began testing it I noticed that Resistor R11 which seems to be a bleeder
resistor in parallel with the power electrolytic filter capacitor C14 was
badly overheating. I tested its resistance and it read 49.7Kohms. I first
replaced all three electrolytic capacitors in the radio, but the resistor
continued to overheat. I then decided to disconnect all the loads from the
power supply and only kept the CH1, C14 and R11 PS filter components
connected. I did this to try to isolate a short somewhere down stream of the
PS. R11 continued to overheat though. I then took out the 5U4 rectifier tube
and measured the voltage at pins 4 and 6 and they read around 650V AC! They
read the same thing with the tube inserted. The Rectifier filament secondary
read around 5V AC, and the other filament secondary read around 6V AC. I can
get exact voltages if needed.

So it would seem that only the HV secondary of the power transformer is
putting out an over voltage as per the manual those pins should read around
560V AC. Also, I have taken DC voltage measurements across R11 while still
in standby, and when I put the Phone/CW switch to CW I read 650V DC, but
when I switch it to Phone the voltage drops to around 560-580V and then at
this point R19 and R17 start to warm up as well.

I have gone through the soldering and everything looks original, nothing
looks out of place. The radio was operational at some point as it has
markings on the front for the different bands it used to be tuned up too. I
have gone through every capacitor and resistor and have tested their
capacitances and resistance. Although some are a bit off I found no shorts
or opens. I have been replacing the components that are a bit off as I get
the parts in. 

I was wondering if anyone else has experienced this before with their 680 or
similar rig. I find it very odd that the transformer is reading 650V AC at
the HV secondary taps. Shouldn't it read more like 560V AC? I thought bad
transformers go down in voltage not up. My AC outlets are reading 115-120V
AC by the way. :)

Thanks for any insight you might be able to shed on my little problem as I'm
stumped.

Joel
KG4INU