Re: Re: Burning through Pilot Light Bulbs

[Mitch]

Thanks Robin!

I’ve had a bit more time today to play through the amp and poke around a bit with a chopstick and a multimeter.

First off, I couldn’t replicate the powering down problem from yesterday, even though I left the amp on for over an hour on two different occasions, and was able to play through it for about 20 – 30 minutes during each of those periods.

I bought some more 6.3V bulbs from Radio Shack, and that seems to have solved my pilot bulb problem – the replacement bulb is still alive and well after being lit up for more than one hour. Andy thought maybe the bulbs I received in the kit were from a bad batch – that seems consistent with what I saw today.

As far as the “static” sound, it was much reduced today, and I was only able to hear it on a couple of times. On one such occasion, it continued on even after I completely stopped playing, and I was then able to get the chopstick and poke a bit. When I poked on the socket where the output transformer is attached (Pin #4 on the power tube), the static stopped.

I don’t think the problem is a cold solder joint, but I’m wondering how tight the tubes should be in their sockets. The Power and rectifier tubes on my amp seem pretty loose. They don’t fall out on their own, but I can very easily “rock” them back and forth in the sockets with minimal pressure (compared to the preamp tube). Could the static problem and the previous powering down problem be due to tube pins that are loose in their sockets? Can the sockets be tightened up?

I don’t know if these voltage readings are helpful at all, but here is what I’ve measured:

Green heater wires at pilot light, power tube, and preamp tube: 6.4V AC
Power tube plate (pin 3): 373 V DC
Power tube grid (pin 4): 338 V DC
Preamp Tube plate (pin 1 and 6): 152 V DC

These numbers are a little higher than the expected range given in Hunter’s book, but are still below the values he gives as being at the upper limit of acceptable.

I am trying to add pictures of the chassis using the “attachments” function but I do not see them appearing here in my message. After I select the photo, it returns me to this text screen, and I don’t see the pictures added to my message.

Thank you again for your time!
Mitch