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Nickthedentist · 13th Jul 2020, 9:56 pm

I bought a pair of "new" Newmarket TO-3 power transistors from them recently to attempt to repair a 1964 Pye 1004 Black Box. They looked the part and had a date code of 1971 on them which seemed plausible. At £25, they weren't cheap.

They passed a quick AVO test, though worryingly, one read very differently to the other on my Peak Atlas tester; one was always recognised as a PNP transistor with sensible gain, the other always came up as a diode pair.

In spite of all the passive components and preceding transistors being removed and meticulously checked, I could not get the amplifier to work properly, with my bench supply tripping its current limit, whatever the setting of the bias pot.

I'm not clever enough to say whether or not the supplied transistors were faulty, and it's far too late to think about returning them, but caveat emptor.

N.

13th Jul 2020, 9:56 pm	#27
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,854	Re: Littlediode I bought a pair of "new" Newmarket TO-3 power transistors from them recently to attempt to repair a 1964 Pye 1004 Black Box. They looked the part and had a date code of 1971 on them which seemed plausible. At £25, they weren't cheap. They passed a quick AVO test, though worryingly, one read very differently to the other on my Peak Atlas tester; one was always recognised as a PNP transistor with sensible gain, the other always came up as a diode pair. In spite of all the passive components and preceding transistors being removed and meticulously checked, I could not get the amplifier to work properly, with my bench supply tripping its current limit, whatever the setting of the bias pot. I'm not clever enough to say whether or not the supplied transistors were faulty, and it's far too late to think about returning them, but caveat emptor. N.