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04/11/21 at 05:50:00 


       


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Transformer blown.  "Not worth repairing". (Read 217 times)
Peter L
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Transformer blown.  "Not worth repairing".
11/22/20 at 10:48:47
 
Hi, Steve and all.   I purchased my Zen Triode Integrated (S/N #59) back in 2003, and enjoyed it happily for many years between London, Tokyo and now I'm in Hong Kong.  

Unfortunately when it arrived in Hong Kong.  I forgot that, even though the amp says 120v/240v at the power input, the switch to set the amp to accept the appropriate voltage is manual and is tucked away inside the machine.  The fuse went. I replaced the fuse, set the voltage switch appropriately and tried again with no luck.  Left channel is completely dead. I had it sat on the shelf for a few years meaning to get round to fixing it.   I took it to a local place yesterday.  There's a thriving community of audiophiles, used gear shops and repair shops in Hong Kong.

They told me the big transformer on the left channel was blown.  And that I should replace both of them to match the sound (seems fair),  but the cost would be around $400 for parts, and probably another $600-700 in labour, bringing it to a total of over us$1000 to fix.  Again, assuming there weren't other components that needed replacing.  They had a bunch of used mass-market tube amps lying around that they were selling for less than that, so their advice was just to get another amp.

Now firstly, I don't want to compare a mass-market PCB tube amp with the glory that is a hand-made zen triode amp... but also the cost seemed a bit steep, to me.

Can you advise what options I have?  I'd consider shipping the thing back to you if repair were an option at a reasonable cost. Am I chasing a lost cause?
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Steve Deckert
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If the 1st watt
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Re: Transformer blown.  "Not worth repairing".
Reply #1 - 03/19/21 at 21:12:28
 

Regarding the switch to change the voltages - we have never built any amplifiers with a switch, so perhaps someone added it along the way?

That said, remove the rectifier tube, change the fuse, and try to power the amp on again.  If it blows the fuse with no rectifier tube installed then you know the power transformer is blown.  There is no way to blow the output transformers, so someone misdiagnosed the issue.

The power transformer can be replaced with a Hammond 372FX which may be available in your area.  I am amazed at the labor prices.  We don't even charge that much here.  You total bill including labor here would run less than $400.

Steve
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Peter L
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Re: Transformer blown.  "Not worth repairing".
Reply #2 - 03/20/21 at 06:43:36
 
Promising news after all!   Thanks for the reply.

The switch was a special request on my original order, as I was in the process of moving between Japan and the UK.

Right.. the transformer they said was faulty is definitely the power transformer.  They probably didn't investigate far enough to realize it at the time.  The fuse doesn't blow, but it gets hot and crackles with or without the small middle tube installed.  The cost quoted is indeed a rip-off, especially considering it's a us$125 part, shipped.  Would you agree there's no need to replace both sides, as it's not part of the output?

Also, one of the big capacitors has soiled itself.  Easy to replace. Maybe best to replace them all after all this time?

Thanks for your advice.  I'll shop around again locally for a quote to replace that transformer (and the caps).  It should help that I can purchase the parts myself at a reasonable price.

Peter. Smiley
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Steve Deckert
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Re: Transformer blown.  "Not worth repairing".
Reply #3 - 03/23/21 at 04:41:02
 
No need to replace both sides because the specs of the Hammond transformer should be an exact match.

I would replace the caps as well.

Good luck on your adventure!

Steve
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