Burned Up Transformer in HiFi 6p3p Tube Amplifier

[dmitch31]

Hello all,
I'm hoping you can give me some direction here. I recently purchased the HIFI6p3p amplifier from a chap on eBay. The guy I purchased it from was not a seller but rather a hobbyist who had owned the amp for awhile.

Upon receiving the unit, I connected a Sony 5 disc CD changer/player and two Polk speakers and began listening. It sounded very nice, and I was pleased. This was the first (and only) night I had (or have ever since) listened to the amp.

I went to sleep, for the night, listening to this amp play music. At about 4:00 in the morning, I woke up to this very strong burnt smell permeating the house. I could tell it was coming from the amp, so I got up and unplugged it from the wall and then just went right back to bed.

Next day, I try to turn it on, and it will not turn on at all. No light, no sound, no led, no nothing. So I take the cover off, and lo and behold, the transformer is burned up. I have included pictures below.

I have never worked on an amplifier like this, but I and my co-worker have done a lot of electronics repair and definitely know how to solder and replace parts.

So, my questions are:
1) Where do I get a replacement transformer for this?
2) What caused the transformer to burn up in the first place?
3) How do I prevent something like this from happening again?
4) Was it something I did, or was it just ready to go?

Your insights are GREATLY appreciated!
Thank you!

[TPStatic]

Sorry your transformer toke the smoke test
Looks like the primary side drew to much current.
I'm surprised (and then not)the fuse didn't go first.
I would first check the manufacturer to see if they offer any assistance, especially with the a replacement trans and schematic. Maybe they want to make a good impression here in the states.
I would check the specs to see if they cross over to Hammond if so check with their parts vendors to see if they have a replacement.
If that bombs out , try this guy Boris
info@engineeringvista.com He is out of Glendale, NY but has delivered some nice transformers for me. Give him the specs ,perhaps he can help.

[Akita]

I think you need a bigger transformer. Like Hammond 272HX (x19). You should take a look at the psu design. It will be better if you can get the schematic.

[kevinkr]

Probably due a somewhat undersized power transformer, perhaps poorly ventilated in addition, or possibly the amplifier experienced a malfunction (like a failing supply capacitor or an internal winding short) while you were sleeping.

The specifications printed on the transformer should assist you in finding a suitable replacement. I would increase the ratings if possible. (40VA is pretty small for even a small power amplifier.) Getting one from the vendor in China is probably not your best recourse provided that they pay any attention to you at all. Shipping will make it cost more than a superior locally sourced component from Allied, Hammond or Edcore.

Tube amplifiers should NEVER be left running unattended, there is some potential for mischief if something goes wrong, and invariably these are not UL/CSA approved and are only about as safe as the guy who designed it cared or knew how to make it - not to mention the potential corners cut by the manufacturer.

Potentially catastrophic failures are not that uncommon in artisanal and diy tube hifi gear, and I have had more than one close call over the last 30yrs due to failing components. (This incidentally is also true of any vintage solid state gear, and is by no means unique to hifi equipment.) I am always nearby when my system is on, and everything is in metal and well fused, even so smoke and soot from burning components can make a lot of mess inside and outside of the device that malfunctioned. The fact that I was close by and wide awake in every instance has averted anything more than a little stink and an inconvenient repair.

Be safe! If you must use it this way put it on a timer that turns it off an hour or so after you go to bed. An earth friendly baking soda based fire extinguishing system like those used on the M1 tank might be a worthwhile improvement.. Sorry couldn't resist...