EL 34 Glow stick Tubes

[lesexypaul82]

Check these EL34's in my JCM 2000 TSL.. Never seen anything glow so brightly.. Even preamp tubes..
I like the big group Shot..

Is this how bright tubes should be? None of my other amps light up like that.
Bias is 65 and 64 mV using probe spots on the back... its a 2005 with rev7 board from factory..

Amp plays great.. played for awhile (while checking and listening for anything odd) but nothing.. Not a hiss, pop or hummm...

 

[Spanngitter]

And your Heater Voltage is?

 

[lesexypaul82]

Is that even testable.. Im sure it is but the tubes are PCB mounted.. ... But id assume thats a set voltage and is nothing like the older amps which are fed straight from the tranny..
If you know how to check these thing on a JCM2000 TSL let me know

this is all MArshall say

 

[Pete Farrington]

It’s difficult to give a specific procedure to do that, unless an identical model amp chassis happens to be on the bench

But for most amp designs, it’s usually possible to access the valve socket lugs fairly easily. That being the case, it just needs the appropriate lugs being probed, eg 2 and 7 on octal output valves.
Meter set to V AC.
Amp powered up but probably best left in standby mode, to reduce the risk of probe tip slippage causing bad things to happen.

We’re looking for 6.3V AC. Preferably not higher than 6.6, over 6.9 would be bad, may cause overly bright heaters

 

[Spanngitter]

Be aware that the first 3 PreAmp Valves are DC heated on the TSL100 so your DVM needs to be set to Vdc instead of Vac.

 

[Tatzmann]

Fwiw, i got EHX EL34 in my 2000DSL and they also emit this dark strong orange glow from the heaters in that amp, in others little less so.

My voltages are all in the comfortzone.

Nothing to worry i'd say, for now. But measuring voltages isn't a bad idea.

Or, if it gets more intense just put the whole thing inside the Marshallfridge, preferably in the freezersection.

 

[lesexypaul82]

I havent given as much play time to the JCM2000 as i had the JCM900 or 800..
Was just a bit shocked to see them at least (if not more) double as bright as the other.. Let alone the pre amp valves as bright..
Ill have a prod around inside later this weekend.

 

[TheKman76]

Great shots, by the way.
Colour temperature looks fine to me. If they were too hot I'd expect a whiter colour, this looks perfectly orange. I does look like there is just more of the heater exposed in these valves.