Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TubeGeek on June 11, 2013, 07:24:11 pm
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This little amp came to me for repair today. Thought I'd share pics cause it's not too often we see these WEM's. It's my first WEM.
Obviously the filter cap exploded so that's gonna be cleaned up and replaced. After that, I'll test her out and see how it's operating.
The owner said he or his kids turned it on and left it on for a few days, weeks, who knows and they heard it pop and then the magic smoke came out. The pilot light was burned out so nobody knew it was on. :BangHead:
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Ahhhh.....there's nothing quite like the smell of cooked electrolyte :icon_biggrin:
That stuff is pretty toxic, so don't be snacking while your cleaning that out :l2:
I bought a Mesa combo off of a guy who had left it on for weeks?/months?......I think he liked the look of the purple indicator light glowing in his apartment :dontknow:
Unfortunately, I found this out after the amp failed in the middle of a show.....I turned around during a set and that same indicator was now OUT,,,because the filament path off of the power board was melted, lifted and open
I had to refrain from punching him square in the face :angry: :violent1:
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Our bass player, many years ago, used to use a WEM PA amp of similar vintage to yours for his bass. Filter cap went in spectaculr style just before a gig! Whilst I had it on the bench I wanted to give it a thorough overhaul. I discovered that Charlie Watkins himself lived about a mile away from me in South London, so I went round had a chat and he gave me the schematic for it! Lots of old interesting stuff in his garage - he was just starting to make the Copycat again at the time.
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YUCK! Man what a mess.
I was wondering if when an old type of electrolytic cap explodes like that do you need to neutralize any chemicals left on the chassis?
Like with baking soda and water? I don't know what type if any chemicals would need to be dealt with.
Brad :think1:
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How DO you get that black stuff off? Mineral spirits?
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How DO you get that black stuff off? Mineral spirits?
That is a good question! It'll be a few weeks before this particular amp is on the bench but I'm looking for suggestions. I was planning to try and scrape/peel/pull what I can off the chassis and then use something to get around the components it sprayed onto. Isopropyl? Goo Gone? Acetone (probably not), degreaser ??? :think1:
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The white stuff is mostly paper and *borax*. Mildly alkaline.
The "black" is probably corroding metal.
> be a few weeks before this particular amp is on the bench
I would not let that stuff sit!! Water will remove borax. Alcohol will remove water. Heat to dry.
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Cleaned it up a little. Not hard to remove the sh*t at all.