Fender Twin Pilot Light Flicker

[mrr3000gt]

Gang,

Got a question: my brand new Fender Twin Pro 100 seems to have a nice feature: while playing it today I noticed that the pilot light would flicker when I would strum chords. The tubes remained a consistant glow and there was no loss in tone or sound (like what might happen if the power supply was sagging).

I know from building amplifiers that the pilot light is in the heater circuit and a responsive flicker should not be possible. I did a search of this and the only things that came up was failing bulb. The bulb shines fine when not playing, but playing makes it respond to my playing.

This is kind of cool if it is a feature of the amp but not if something is going wrong.

Has anyone heard of this in the new Fender twins (especially the Pro 100s)???

[LooseChange]

Probably a slightly faulty bulb socket.  Seen many times. Mess with the two tabs that the wires are soldered to.

[Willabe]

Hi mrr3000gt,

I don't think they would bother with such a "feature". Sounds like a loose/bad socket, bad bulb, or bad solder connection to me. Have you opened up the amp for a look see?

You could take a chop stick and poke the fillament wires a little and see if that makes it fliker. Bulbs are cheap, try changing it.


         Brad          

[mrr3000gt]

I do repairs in my area (even get to fix my own equipment!), and I have not had it apart yet. It is literally only two weeks new. I have not even verified the bias. I did do a bunch of searches and the new Fender twins, reverbs, and hotrods seem to be affected by this and its a mechanical problem: bad solder, socket spring tension, bad bulbs.
I figured someone here might know something specific about this if its an issue. I was hoping it was something known and not serious.

I do hate fixing my own gear as I dont get paid...

[Willabe]

Sounds like you already have it tracked down, and it does'nt sound serious. Probley take you more time to open it up and put it back together than it's gonna take to fix it. Yeah it's a pain but I can think of worse things to have to do.


         Brad         
   

[rafe]

believe it or not it's the bulb. I had the same problem in a 64 vibroverb custom... Got some NOS bulbs on E-bay and it was cured instantly.....If you would like the vendors name I'll be glad to get it for you. thew are cheap too.
It has something to do with the fit I think...the contact is lame. And the bulbs are garbage.... Take off the jewel and wobble the bulb around and it should flicker , the vibrations are causing it !

[mrr3000gt]

Well, I took the bulb out and filed the end of the bulb with a microfile in the event it was the cheap cold solder-looking bead on the end of the bulb itself. I put it in and played for about an hour or so and no flicker...Does not mean it fixed it, but it was easy to try.

I will just wait and see if it happens again and open the case up.

[rafe]

I too did that and it worked for a while then started again......maybe you'll be lucky. 

[mrr3000gt]

Not that lucky: it took about four hours of playing (its just getting dim when I play real loud and rock the cabinet).

[zapped]

I would take that bulb out and add a little more solder to the tip...

[rafe]

NOS GE's 

[mrr3000gt]

Where do I get NOS GEs? And where are they currently sourcing bulbs from???? The same factories that make running shoes? 

NOS GE's 

[plexi50]

Squeez the socket on the sides to make a tighter fitting bulb in the socket to make a better ground connection

[rafe]

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.l2557&rt=nc&nma=true&item=150548972661&si=GPxesFOVeuM7WeCyhY92OG6NKS8%253D&viewitem=&sspagename=STRK%3AMEWNX%3AIT

[mrr3000gt]

So what do you think the issue with the flickering bulb is for the twins and hot rods?

[Willabe]

So what do you think the issue with the flickering bulb is for the twins and hot rods?

It sounds like from what you and the others have posted it's....

1 - bad/cheap or slightly too small of a bulb base, so it's not fitting in the socket tight enough to stay in place as to with stand the vibration of the amp when turned up loud,causing the bulb to break solid contact with the socket intemitantly, hence the flicker. Thats why it's fine with no flicker when you'r not playing.

2 - bad/cheap or slightly mis-sized socket, causing same result, flicker.

3 - maybe both.

Bulbs are easier and cost less $ to change, and there's nothing wrong with having an extra bulb or 2 laying around. Like said in earler post above get a few good bulbs and try it.

If that does'nt get it, get a good socket and try that. Doug sells both.


              Brad