Problem with Tung Sol 5998 (solved)

[buddha2015]

Do I need a tube tester ? I work in a service center for electronic appliances and we have lots of tools available.

[Paul Birkeland]

Yes, being able to tell the seller of the tube that you tested it on a specific tube tester and obtained failing results is helpful information on the road to getting a refund.

[buddha2015]

Thank you guys for great & immediate support so far 

I am still open to other suggestions that could help resolving the problem.

Not sure if there is a tube tester around at my workplace.

[Doc B.]

You could try measuring the tube for a short. Clip one test lead to pin 7 and then see if you find a very low resistance reading to any other pin beside pin 8, which of course will read very low since 8 is connected internally to 7. I don't think you will find a short based upon your description of the problem, but it's easy to check.

[buddha2015]

Thanks. No short.

[Doc B.]

I think PB is right that you feel you need to support your case you might find a tube tester and document that the tube has low emission or low/zero transconductance. It certainly should be working with 6V on the heater.

It is possible that some wire that extends from the tube structures down into one of the pins is broken or loose. Unfortunately this is pretty much impossible to measure. In rare circumstances one can reheat the pins and reflow the solder that anchors the wire to the inside of the pin. I have saved a few tubes this way, but I would be hesitant to take an iron to a tube that I might try to return for refund.

You might also clarify with the seller how he determined the tube was working. If he just checked to see if it got hot then he would have assumed it to be working. If he used a tube tester he might have recorded the reading he got. If he tested it in an amp to check function and heard music then it most likely did get damaged in shipping.

The last resort I can think of would be to double check that all of the pins are getting adequate contact in the socket. Sometimes pins are slightly different diameters or they might be slightly bent and it's possible that a pin is not making full contact even thought that same pin on the 6080 is connecting well to the socket. Wiggling the tube in the socket can sometimes show that there is an intermittent connection.

[JamieMcC]

Hi if you put added your location to your profile maybe you might live close to someone with a tester who might help.

[mcandmar]

In my experience any tube that gets hot but doesn't visibly glow has got air inside it.   Does it still have the shiny getter material on the glass?

Go back to the seller anyway, i have bought tubes from eBay that have died in transit and always got a refund from the seller.

[ALL212]

I've been running a 5998 tube in mine for some time with no issues.  I'd go with the bad tube theory also.

[Grainger49]

To summarize, they are saying a good 5998 works in the Crack.

[Nathan]

I'm listening through my 5998 right now- no issues at all

[buddha2015]

In my experience any tube that gets hot but doesn't visibly glow has got air inside it.   Does it still have the shiny getter material on the glass?

Go back to the seller anyway, i have bought tubes from eBay that have died in transit and always got a refund from the seller.

Thank you everybody for their input.

My tube does not have the shiny getter material on the glass. There is a very clear circle above the getter and some whitish material around.
There are some glass pieces inside the tube (seller told me about them) and on close inspection also white powder.
I just found out that I can rotate the black base slightly against the glass part.

I guess my tube has sucked in air ?

[ALL212]

That whitish material doesn't sound so good.  That usually the color the flashing turns if it is worn out or air has snuck in.

[buddha2015]

Ok folks, here comes the solution. It is bad news for me I guess.

I had almost forgotten, that pictures had been taken of the tube when it was in transit. I used a freight forwarder to ship the parcel from the US to Austria and for insurance reasons photos had been taken from the contnents of the parcel when it arrived at the depot in the US. The photos were uploaded to my account.

Here they are:

the tube when it arrived at the depot:
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fabload.de%2Fimg%2Ftube1g5phn.jpg&hash=f7993da323f9e7edd5249ee7e9993c5f8f599be7)
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fabload.de%2Fimg%2Ftube27uqlq.jpg&hash=71e503bcfc5a8b712a5ed6900c3838e66b2bf6ac)

the same tube when I received it:
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fabload.de%2Fimg%2Fresizeof20150704_1347x1onj.jpg&hash=a7f94f4cc60031e6eb879878f33ce869379f8de2)
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fabload.de%2Fimg%2Fresizeof20150704_13478tr0z.jpg&hash=4de7db54d642b268b3a2a1291d4138f59fcbcc5a)

You can clearly see that the dark getter material has vanished from the glass.

In this case it is most likely that the tube has been damaged when on the way to Europe.
I am unsure if I can still start a claim with the transport insurance, as I received the parcel visible undamaged and I accepted it from the post office without hesitation. I must admit the parcel was packed well and I cannot really blame the seller. Maybe someone at customs dropped it ?
Or I was just unlucky. 

[mcandmar]

Yup thats what i suspected, the inside has filled up with air so its useless now.  Most likely a crack developed where the pins enter the tube, due to said wobbly base.

Are you saying the tube was unpacked and photographed at a shipping Depot?    You can clearly see the getter starting to erode in those first few pics which implys to me that is when it got damaged.