Premier 140.

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toprepairman
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Premier 140.

Post by toprepairman »

Greetings from London.
I have a troublesome 140 with an odd fault that I have heard mentioned elsewhere.
On UK mains so could well be 245+ Volts.
When switched on, occasionally one of the 6550's will spark internally, accompanied with a loud crack in speaker (no surprise), and blows the 1A fuse. This can happen to different valves randomly (I think) though I have only witnessed it once. It has winged C Svetlana's fitted.
Is this a valve problem? I cannot see anything obvious in the circuit wrong.
This amp did have a seperate problem with one of the zener chains cooking up and flashing over on the board, but this has since been cured.
It always works perfectly if wound up on a variac.
Any help please?
Regards
Henry
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Re: Premier 140.

Post by admin »

Hi Henry,
Welcome to the site. Not sure what the problem is but I would first check that it happens with other tubes as well. You mention it happens with different valves but your not sure. I would rule that out first as a tube is easily replaceable if defective. If it's not that, you can try working through the circuit to test each component. We have the 140's schematics in our database so if you don't have it you can download it for reference. Let us know how it turns out.
-admin
Home Theater in Member Gallery
Main stereo: ART Amplifier and ET7s2. 2nd stereo: PV-14L and MV-55. Previously Owned: PF2 preamp, Evolution 2000 Amp, PV-12AL preamp, D/A-2b Vacuum-Tube Digital Processor.
toprepairman
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Posts: 14
Joined: Fri May 23, 2014 3:40 am

Re: Premier 140.

Post by toprepairman »

Hi, thanks for the reply.
I did replace the one that sparked with a GE valve and it didn't happen to me again. I ditched that one valve as it would always be suspect anyway. However when being used by the owner who had fitted another Svet 6550 it then sparked and took out the other fuse, but I did not witness any of this and it has since reappeared on my bench. Running up on the variac again it has been faultless.
I have since heard that it did spark but rarely for a previous owner. I have also read somewhere, but don't remember where, of just this problem happening to other examples of this amp, so was hoping it may have been a known type fault.
Could perhaps switching to KT120's resolve the issue?
Henry
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