Motorola ts907 low hv

[timmy]

So even though the tube is not getting super hot it could still pull the voltage down.I forgot to mention the 2nd chroma 6bL8 tube while I had the chassis on the bench and plugged in checking things I noticed this tube had what looked like a blue spot on the side of the tube but once in the cabinet I didn’t see it again.

[Yamamaya42]

For the case of V6 if it was having an intermittent H-K short (+190v to Y-HEATER/GND) the tube would not heat up very fast, your PWS might give up first, R215 before the tube got really hot, unlike when the audio tube or HOT was overloaded, and all the power was pushed to the plates, and the tubes heated very quickly.

[timmy]

What do you think of that 2nd chroma tube I mention in the last post.

[Yamamaya42]

a little blue glow is normal, it's just a spot of excitation from being hit from electrons.

I got a picture of a really weird one on a rebuilt CRT i got last year.

[timmy]

I thought any blue may have been gas in the tube.

[timmy]

Where did you get a blue mark on a crt

[Yamamaya42]

https://i.imgur.com/0ykFyqZ.jpg

Blue is not a problem.

pink , purple is.

https://tonetopics.com/tell-amps-tubes-gone-bad/

[timmy]

When I first started working on this set when I couldn’t get good hv I noticed the top of one 6jm6 was glowing blue I put another one in And that was what fixed the hv problem.

[Yamamaya42]

perhaps what you saw was a bad tube with a purple gassy glow, like seen here,

https://i.imgur.com/z7NnpHg.jpg

and not a normal healthy blue glow of a working tube?

[timmy]

I just for giggles tested the audio output tube and it showed grid emission it’s a new tube and didn’t show this when I got it would this be caused from running hot because I’m still not sold on the fact that this tube is supposed to run hot. The volume control is 2 meg I tested it at 2.4 meg.

[Yamamaya42]

as mentioned. audio output tubes get HOT!

2 alike tubes.


https://frank.pocnet.net/sheets/049/6/6AQ5A.pdf 10w max gets up to 250c!
http://www.nj7p.org/Tubes/PDFs/Frank/127/6GK6.pdf 17w max no heat listed, but you can bet it also gets over 200c.

this is normal

[timmy]

Ok I’ll leave it alone just don’t get why it’s now showing grid emission

[Yamamaya42]

Originally Posted by timmy

Ok I’ll leave it alone just don’t get why it’s now showing grid emission

As others have pointed out, don't take what any tube tester tells you as gospel, it's just a guide.

http://www.tungsol.com/html/faqs3.html

[timmy]

Lol got it.

[timmy]

When I got tubes for the set I had got 2 6eh7 tubes GE and I usually test them and in testing them they were completely dead no reading at all. Just never know what you might get. Someone should come up with solid state versions of tubes or if it can be done at all.