Seeburg V200 tube life question

[jeffinmn]

So, I've had my V200 since around 2003. I replaced the paper caps and filter caps in both the amp and selection receiver when I got it and used it a lot the first few years I had it. I used it less often the last 10 years or so but recently got back into using it daily. 

I noticed that after the jukebox had been in use for an hour or so there were a couple of selections that would not pickup. I have a Hickok tube tester model 539B and it says when testing the 2D21 tube that the tube should strike when the grid voltage is around 1.8volts. Some tubes strike a little higher and some a little lower and I'm not sure when it's higher or lower than 1.8 is the tube good or bad. Anyway I swapped out the various 2D21 tubes one at a time and found the problem went away after changing out the write tube. I have several new old stock 2D21 tubes.  The V200 works reliably now.

That got me to wondering how long do the tubes last in a V200. Obviously it's tied to hours of use. I also notice when the Jukebox is not playing that the 5U4 tube is not in use so I believe there is no plate voltage in the amp. The 6L6 tubes don't get very hot when the jukebox is on but not playing anything. Does the 5U4 tube being off when not playing a record help the amp tubes last longer? 

I have a collection of 1938 and 1939 Zenith radios. A couple I've used somewhat regularly for 30 years. I've never had a tube get weak enough to need replacing on these radios. I always put a very good set of tubes into the radios after they are rebuilt. 

Anyway, thoughts on tube life?

[robnyc]

Jeff, tubes in jukes and other commercial devices are operated conservatively. Amp tubes can last for decades. I have some voltage amp tubes in jukes that date to around when the machines (VL-201) were new. they are in revenue service and still test Ok -though not as new.

Thyratrons are an exception as they dissipate a lot more than an amp tube. The 2D21 circuits in the V was hastily revised as the frequent failures surfaced during the first months of production.

Tube tester are not (IMO) adequate for testing them. They are power handing devices which essentially switch at the zero interval of an AC line (if used on AC). You need a real-world load to get valid results. If the 5MFD capacitor have been replaced in the stepper and it is in otherwise usable condition, it can be used to test the thyratron tubes. Place a tube in the stepper socket, allow at least a minute for warmup. Touch to stepper signal terminal to chassis ground to fire the tube. While it conducts, look inside the plate area. it should be a deep blue-violet. A lighter blue indicates a tube that can no-longer provide adequate emission.

I converted all the V machines I intended to use commercially for TSR3 receivers and even then found that the 2050 was a PIA when used in heavy service. I came up with various mods to get rid of them going back as far as 1989.

There are probably mods that can be used to get rid of the 2D21 as well, but I never looked into doing so.

RobNYC