Help with amp repair

[markof]

My Ariand valve amp fried this afternoon during an electrical brown-out - lots of blue smoke emanating from the bottom of the amp. I've never seen or smelled anything like it before.

Any recommendations on someone good in Ireland to effect repairs?

Also, any recommendations so this doesn't occur again?


Mark.

[tony]

Hate to hear that happening. Surprised nobody has responded yet to this but I am sure you are aware of the obvious candidates Cloneys or the Hifi Hospital?

Cloneys I am sure you know but details for the hifi hospital are below.

Hi-Fi Hospital The (Dublin 15)
Unit 7 Block 8 Blanchardstown Corporate Pk Dublin 15 Co. Dublin
(01)8829375


There is a guy also that GiantHaystacks knows but he is in the north. There is a hifi store in Cork/limerick (cant remember the name)

Best of luck with it let us know how you get on. Hoping that I wont need the service ever.

[Fran]

Most likely a cathode resistor or plate resistor on the el34s I'd say. Repair possibly complicated by damage to the pcb, but should be fixable for reasonable money. If the transformer is damaged the price will rocket fairly quick. I would start by asking the manufacturer/agent for a schematic..... That would greatly aid the repair.

Fran

[markof]

Many thanks for the replies and quality information.

We also had a router and a clock radio demolished in the brown-out. I wonder if there is any point in trying for recompense from the ESB?

Will try to get the schematic from the agent - great suggestion.

Out of curiosity. I removed the bottom plate of the amp. A large capacitor on a daughter board (probably part of the power supply) had swollen and ruptured, releasing oil into the amp. I think that this was the cause of the large volume of smoke.

Luckily I have a fall-back amp here in the form of an Arcam Alpha 10, which actually sounds pretty good in my set-up - bit more bass, bit less middle and high end, but plenty good enough in the interim.

Anything I can do to prevent a future occurrence?

Mark.

[Fran]

First off my standard safety warning!! There are lethal voltages in there (DC is much more deadly than AC) and its quite possible the high voltage circuit is still charged. Please be careful - don't go poking around in there with your fingers!!
**************************************************

Yes, when a cap vents its a spectacular affair!!

Probably not much you can do really on it I'd say. Always turn off all that stuff during power disruption. Its not the brown out as such that causes the problem but the power coming back AFAIK. What happens is power comes back, there is a sudden large demand downstream from the nearest ESB transformer. The voltage drops slightly and then gets compensated, by the time that surge hits your equipment the demand has passed, the voltage is now suddenly higher and the "shock" blows out a stressed component. The main reservoir cap would be an item that gets a bit of wear and is subject to the highest ripple current. If the cap does not have a very conservatory rating it might well blow.

Most likely the cap needs replacing and it might well be wise to replace the few other main reservoir caps too. After that there may still be the odd resistor taken out too.

Is the amp on a PCB or point to point wired?


You could try the ESB but I'd imagine it wouldn't be easy!!

Fran

[markof]

First off my standard safety warning!! There are lethal voltages in there (DC is much more deadly than AC) and its quite possible the high voltage circuit is still charged. Please be careful - don't go poking around in there with your fingers!!
**************************************************

Yes, when a cap vents its a spectacular affair!!

Probably not much you can do really on it I'd say. Always turn off all that stuff during power disruption. Its not the brown out as such that causes the problem but the power coming back AFAIK. What happens is power comes back, there is a sudden large demand downstream from the nearest ESB transformer. The voltage drops slightly and then gets compensated, by the time that surge hits your equipment the demand has passed, the voltage is now suddenly higher and the "shock" blows out a stressed component. The main reservoir cap would be an item that gets a bit of wear and is subject to the highest ripple current. If the cap does not have a very conservatory rating it might well blow.

Most likely the cap needs replacing and it might well be wise to replace the few other main reservoir caps too. After that there may still be the odd resistor taken out too.

Is the amp on a PCB or point to point wired?


You could try the ESB but I'd imagine it wouldn't be easy!!

Fran

Thanks for the warning. I left it a day before opening the amp and was careful to look but not touch and will be as careful when replacing the cover.

Am waiting to hear back from the ESB - most of the road I live on had varying degrees of damage - washing machines, central heating controllers etc. So we may have a case.

The amp stopped working and smoked during the brown-out phase but there may have been a surge immediately beforehand and I did not notice as the valves normally keep working for 20-30 seconds after I switch off. I'm just glad my electrostatics did not go as well.

The amp appears to be a mix of PCB and point to point wiring. Will this make a big difference?

For the future, should I be looking at surge protection - will a protected power bar, such as a Tacima do?

I'm down here in Cobh, and will probably try the HiFi Hospital for the assessment and repair - any experience with them?

Thanks again.

Mark.

[Fran]

If a few houses were done you stand a much better chance!

Don't know the HiFi hospital - just don't know tbh. There aren't many lads that do valve amps - and I'm the other end of the country. Pcb can make it harder but if it's only the caps gone then it should be ok. Sometimes the pcb traces get burnt up which make repair much harder.

Sure you can ring them anyway and see what they say...

Fran

[Ivor]

Scarey stuff!

[giant haystacks]

hi my friend is in enniskillen who fixes hifi -it is a bad time to be going to these people coming up to christmas and all the free view box buisness -if you get it to monaghan i can get it to enniskillen for you -you can speak to him rodney hanna cross st enniskillen get his opinion -he is not hard to pay

[cybot]

Scary stuff indeed! Best of luck with the repair Markof. And to repeat your question: would a surge protector, such as a Tacima, be mandatory for all? And which one is least likely to affect the all important sound of the system?