2a3 valve strange behaviour?

[the_doc735]

hi,

one of my 2A3C valves is displaying strange behaviour:

last night I was sat quiet with the amp switched on. All of a sudden, a 2A3 valve went really bright, there was a slight 'pop' from the left speaker and a sound vibration from the amp like a quiet hum.

I switched it off and left it until today, this afternoon it was fine again!

Anyone actually know what this means/indicates please?

cheers!

[Barry]

It has become 'self aware'.

[the_doc735]

Oh!

:hmm:

the amp has recently been serviced and the 2A3 valves are only a week old!

[walpurgis]

One 2A3C is a dud? I'd not use the amp again without it being checked. Serious damage may be a possiblity. Even the speakers could be at risk.

[Arkless Electronics]

Speakers will be fine. Almost certainly a dodgy valve. Brand new is when they are most likely to fail!

[the_doc735]

One 2A3C is a dud? I'd not use the amp again without it being checked. Serious damage may be a possiblity. Even the speakers could be at risk.


Speakers will be fine. Almost certainly a dodgy valve. Brand new is when they are most likely to fail!

Thanks guys, the Hong Kong supplier has offered to swap/replace the faulty valve! Trouble is at the moment, it's OK again! Very strange. Supply could say: "it's fine".

[Spectral Morn]

Thanks guys, the Hong Kong supplier has offered to swap/replace the faulty valve! Trouble is at the moment, it's OK again! Very strange. Supply could say: "it's fine".

Thing is you need matched pairs or quads depending on what amp it is. If its a valve per channel then they do need to be matched as a pair, if two per channel then a matched quad.

If a valve glows very brightly then its self destructing and about to fail. Thing is, is it the valve or something wrong in the amp.

[the_doc735]

Thing is you need matched pairs or quads depending on what amp it is. If its a valve per channel then they do need to be matched as a pair, if two per channel then a matched quad.

If a valve glows very brightly then its self destructing and about to fail. Thing is, is it the valve or something wrong in the amp.

Yes, it should be quads but they are only willing to send one!
It did glow bright, but the next day and today it has been fine so far?
The amp has only just been serviced by the actual manufacturer (i.e. puresound).

cheers - many thanks!

[the_doc735]

supplier has just asked me: "what datas I need" - what do they mean please? :mental:

[Arkless Electronics]

If a matched quad was originally supplied then there may be data as to the matching on the boxes of the valves or in any paperwork received.. probably a figure in mA. This could be what is being asked for. If not then I haven't a clue...

[the_doc735]

If a matched quad was originally supplied then there may be data as to the matching on the boxes of the valves or in any paperwork received.. probably a figure in mA. This could be what is being asked for. If not then I haven't a clue...

many thanks!

[the_doc735]

If a matched quad was originally supplied then there may be data as to the matching on the boxes of the valves or in any paperwork received.. probably a figure in mA. This could be what is being asked for. If not then I haven't a clue...

yes, arkless! ~ that was indeed what they wanted - many thanks!

AND:

when it goes bad (the valve) does it stay bad 'thereafter'? - you see mine has been fine since that one time a few days ago when it went 'bright'!

[Arkless Electronics]

yes, arkless! ~ that was indeed what they wanted - many thanks!

AND:

when it goes bad (the valve) does it stay bad 'thereafter'? - you see mine has been fine since that one time a few days ago when it went 'bright'!

There are rare cases where it is fine ever after, usually if some foreign matter had been vaporised, causing the flash and curing the problem. This is very rare though and it would be more normal for the same to happen again before long, possibly with worse consequences, but certainly no threat to speakers.

[the_doc735]

There are rare cases where it is fine ever after, usually if some foreign matter had been vaporised, causing the flash and curing the problem. This is very rare though and it would be more normal for the same to happen again before long, possibly with worse consequences, but certainly no threat to speakers.

Many thanks!

PS: new one is in the post anyway!

[the_doc735]

A second valve has gone bright. This may have damaged my amplifier as the input and output transformers became extremely hot and I could smell burning, and were too hot to touch for over an hour!!

The valve supplier are sending a second replacement valve, but could this be the amp and not the valves?

:steam:

[flapland]

I would now get it looked at by someone with the appropriate knowledge, skills and equipment. Sadly I suspect you might have some damage already but perhaps easily fixed. I wouldn't stick in any replacement valve until its checked out.

[Spectral Morn]

If the amp was bought from new, do not accept a repair. You are by law entitled to a brand new replacement amp. I would personally have said don't use the amp until the new valve arrived. Was this brightly glowing valve on the same channel as the first failure.

Frankly if a valve misbehaves my view is replace and bin, unless you want to keep duds as part of a shelf display of valves.

Hope you get your issues sorted.

[Ali Tait]

The dodgy valve may have caused some damage in the amp or vice versa. I would not use the amp again until it has been looked at by a professional.

[the_doc735]

I would now get it looked at by someone with the appropriate knowledge, skills and equipment. Sadly I suspect you might have some damage already but perhaps easily fixed. I wouldn't stick in any replacement valve until its checked out.


If the amp was bought from new, do not accept a repair. You are by law entitled to a brand new replacement amp. I would personally have said don't use the amp until the new valve arrived. Was this brightly glowing valve on the same channel as the first failure.

Frankly if a valve misbehaves my view is replace and bin, unless you want to keep duds as part of a shelf display of valves.

Hope you get your issues sorted.


The dodgy valve may have caused some damage in the amp or vice versa. I would not use the amp again until it has been looked at by a professional.

Yes I think you are right; I need to get an expert opinion FAST!
No, this was manufacturer refurbished a short while ago (not brand new - like new). Yes both dodgy valves on the left side of the amp and the left tranny red hot too!

Which went first? The valve or the tranny? The valve went bright first and then the tranny got hot!

Now the supplier is getting 'funny'!!! ~ They are saying I must return the 2 valves FIRST before they will send out replacement valves. They have said despite ebay rules I MUST pay for the return postage (not them!) AND if they decide that the amp has damaged their valves, I would have to buy 2 more valves from scratch!! Thing is, it was working fine before I put these valves in the amp (i.e. no faults/lovely). And because I have already started a return procedure for the first one, there appears to be no way of cancelling the whole deal and no way of contacting ebay and their system won't let me escalate the 'return' to a 'cancellation' either! Now I don't know what to do? Whether to take it to the local shop (as is) and explain the whole scenario from the beginning, OR remove the dodgy valves and take it to the shop with the original valves back in? This is now a legal battle as well as a technical one! What a nightmare!

[Arkless Electronics]

Probably dodgy valves, simple as that. I've seen this loads of times..... Unfortunately there are valves out there that simply aren't fit for purpose. It's not as bad as it once was.... but still not as rare as one would like!

A recent example, which I actually expected from knowing how dodgy the brand of valve was, is in my own Leak Stereo 20. I was made an offer I couldn't refuse for the Mullard GZ34 and had three Edicron ones brand new in their boxes. Each lasted about 2 days before a bright flash and the HT fuse blowing. Like I said, from experience I was pretty much expecting this to happen. I'll eventually get round to fitting SS rectifiers and that will be that sorted:)

I hope it hasn't damaged your OPT! Ideally fuse should have gone first of course...

[Arkless Electronics]

This may interest you: http://theartofsound.net/forum/showthread.php?41279-Valve-Question&p=698214#post698214

[the_doc735]

Probably dodgy valves, simple as that. I've seen this loads of times..... Unfortunately there are valves out there that simply aren't fit for purpose. It's not as bad as it once was.... but still not as rare as one would like!

A recent example, which I actually expected from knowing how dodgy the brand of valve was, is in my own Leak Stereo 20. I was made an offer I couldn't refuse for the Mullard GZ34 and had three Edicron ones brand new in their boxes. Each lasted about 2 days before a bright flash and the HT fuse blowing. Like I said, from experience I was pretty much expecting this to happen. I'll eventually get round to fitting SS rectifiers and that will be that sorted:)

I hope it hasn't damaged your OPT! Ideally fuse should have gone first of course...

Arh yes! I had heard that there are some valves not fit for their purpose. On forums there seems to be 'for and against' arguments in reliability. Yes I hope I haven't damaged the OPT too? Well tonight after 24 hours cool down, I put the original valves back in and so far they have worked perfectly. The centre tranny there is a slight vibration but it might have been like that all the time anyway AND slight buzz/hum from the left speaker but again it might have been like that all the time anyway? You can only hear it with your ear jammed right up against the speaker with the volume max'd out! The left channel is were the dodgy valves where! The 2 small tranny's run about 30 degrees 'C' and the centre one runs about 34 degrees 'C', however, there are loads of heatwaves from the rectifiers 'hitting' the centre tranny and warming up the casing of the tranny.

[the_doc735]

This may interest you: http://theartofsound.net/forum/showthread.php?41279-Valve-Question&p=698214#post698214

this sounds familiar:

8/ “An output valve has failed in my amp but it still seems to work. Can I continue to use it?”
An amp can sometimes still work with one dud output valve, especially if it has four output valves,(they function as two push-pull pairs) but this will only happen in those cases where the valve fails harmlessly (open circuit) and behaves as if it just isn't plugged into its socket. There will be less power and more distortion under these conditions. It will not be good for the remaining valve on that side that's trying to do all the work though....

Mine seemed to have less power, more distortion, and then ~ the other one on that side also went bright (i.e. trying to do all the work?) !!

[pure sound]

This issue only occurred when the Sovtek 2A3's were replaced with some Chinese made items. Putting the Russian valves back in has resulted in no further misbehaviour.

Personally I avoid Chinese power valves if at all possible. I've recommended that the supplier of these valves is asked for a refund.

[the_doc735]

This issue only occurred when the Sovtek 2A3's were replaced with some Chinese made items. Putting the Russian valves back in has resulted in no further misbehaviour.

Personally I avoid Chinese power valves if at all possible. I've recommended that the supplier of these valves is asked for a refund.

Well, they have said that I can have a refund but without any of the EXPENSIVE postage costs to/from Hong Kong. However, ebay says:

"Here's what we found for "Who pays for return postage costs?"

Sellers pay for return postage if there's a problem with the item. For example, if the item doesn't match the listing description, is damaged or defective or is counterfeit."