The Non Testing of T.V Valves? - UK Vintage Radio Repair and Restoration Discussion Forum

Stylo N M · 27th Jul 2014, 3:24 pm

Hi,

I've been reading some very interesting threads on the t.v restoration all interesting reading,
However without wanting to stir up a hornits nest i was quite suprised to find it quoted that, most t.v valves cannot be tested on a valve tester, or any other type of valve tester, it only gives a general indication of goodness and doesen't hold any bearing on how well it may perform in a working shassey.
So how come this is the case? i was always under the impression a valve tester would test most modern types of valves, or even the older ones provided the tester unit carried the actual valve base for the valve that you wanted to test.

Paul

.

ukcol · 27th Jul 2014, 6:28 pm

Quote:

Originally Posted by Stylo N M

..... most t.v valves cannot be tested on a valve tester.....

Really?

Although it is true that there is no tester (that I know of) that tests line output valves and boost diodes at the very high PIV that they will encounter in a TV set, a valve tester will give you a very good idea of the state of a valve.

No valve tester can run a valve with the exact conditions it will encounter in any given piece of equipment, whatever that equipment may be. If a tester "passes" a valve it doesn't guarantee it will work in the equipment, but if it fails it you can be reasonable sure it won't.

Peter.N. · 27th Jul 2014, 6:34 pm

When I was repairing TVs the quickest to test valves was in a working set, they are running under exactly the right conditions then.

Peter

Ed_Dinning · 27th Jul 2014, 7:39 pm

Hi Gents, substitution was the way the service guy worked, he had a box of valves, not a valve tester in the car. The Mullard HSVT was a sales aid to customers who brought their own valves in to be tested!

Ed

David Simpson · 27th Jul 2014, 8:43 pm

Possibly the reason that some folk think that one cannot test TV l/o/p valves is the lack of B9D Magnoval valveholders in AVO VCM's & Testers, and other testers.
Just make an adaptor from an old B9 valvebase(see my recent thread), adding ferrite beads as an extra precaution against parasitic oscillations. I've tested PL500's on my Mk3 as per the AVO VDM. And wound them up(briefly) on my LeyMarcAvo to a bitty over 100mA DC Ia. Achieving 10mA/V.
But heed recent warnings in threads on using a valve tester to wind up these high slope valves with high Va,Vs & Ia, and leave them running. That's a definite No No !

Regards, David

ukcol · 28th Jul 2014, 1:35 pm

Hi Peter and Ed,

Yes you are right on that more general point.

I worked in the TV trade from 1963 throughout the remainder of the valve era and beyond and the workshops I worked in were never equipped with a valve tester.

The valve tester is useful when checking your stock valves or pulls but was never generally used as a diagnostic aid.

27th Jul 2014, 3:24 pm	#1
Stylo N M Heptode Join Date: Jul 2012 Location: Derby DE1, Derbyshire, UK. Posts: 626	The Non Testing of T.V Valves? Hi, I've been reading some very interesting threads on the t.v restoration all interesting reading, However without wanting to stir up a hornits nest i was quite suprised to find it quoted that, most t.v valves cannot be tested on a valve tester, or any other type of valve tester, it only gives a general indication of goodness and doesen't hold any bearing on how well it may perform in a working shassey. So how come this is the case? i was always under the impression a valve tester would test most modern types of valves, or even the older ones provided the tester unit carried the actual valve base for the valve that you wanted to test. Paul .

27th Jul 2014, 6:34 pm	#3
Peter.N. Dekatron Join Date: Jul 2008 Location: Charmouth, Dorset, UK. Posts: 3,601	Re: The Non Testing of T.V Valves? When I was repairing TVs the quickest to test valves was in a working set, they are running under exactly the right conditions then. Peter

27th Jul 2014, 7:39 pm	#4
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: The Non Testing of T.V Valves? Hi Gents, substitution was the way the service guy worked, he had a box of valves, not a valve tester in the car. The Mullard HSVT was a sales aid to customers who brought their own valves in to be tested! Ed

27th Jul 2014, 8:43 pm	#5
David Simpson Nonode Join Date: Mar 2008 Location: Aberdeen, UK. Posts: 2,852	Re: The Non Testing of T.V Valves? Possibly the reason that some folk think that one cannot test TV l/o/p valves is the lack of B9D Magnoval valveholders in AVO VCM's & Testers, and other testers. Just make an adaptor from an old B9 valvebase(see my recent thread), adding ferrite beads as an extra precaution against parasitic oscillations. I've tested PL500's on my Mk3 as per the AVO VDM. And wound them up(briefly) on my LeyMarcAvo to a bitty over 100mA DC Ia. Achieving 10mA/V. But heed recent warnings in threads on using a valve tester to wind up these high slope valves with high Va,Vs & Ia, and leave them running. That's a definite No No ! Regards, David

28th Jul 2014, 1:35 pm	#6
ukcol Rest in Peace Join Date: May 2003 Location: Harlaxton, Lincolnshire, UK. Posts: 3,944	Re: The Non Testing of T.V Valves? Hi Peter and Ed, Yes you are right on that more general point. I worked in the TV trade from 1963 throughout the remainder of the valve era and beyond and the workshops I worked in were never equipped with a valve tester. The valve tester is useful when checking your stock valves or pulls but was never generally used as a diagnostic aid. Last edited by ukcol; 28th Jul 2014 at 1:45 pm.