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K150-8 smoking...help please [message #22305] Mon, 02 February 2015 10:18 Go to next message
bmacdo is currently offline  bmacdo
Messages: 14
Registered: January 2015
Location: Florida
Junior Member
So the K150-8 I recently acquired seemed to be okay until I noticed white smoke emanating from the top. I powered down and pulled the chassis, got the reverb tank out of the way, fired it back up and waited. The white smoke seems to come from the area directly above the pot for the Intensity knob. There is a bank of 4 dark blue transistors? or resistors? or whatever components they are and the smoke may be coming from those. I don't want to leave it under power for very long in that condition but the smoke certainly comes from that general area, on or around or just above the Intensity pot. This amp has been sitting in a closet for over 30 years and had a big mouse nest inside which I have thoroughly removed and then blew out residual debris with gentle compressed air. I see no evidence that mice have chewed up wiring. This seems fairly serious...any advice? Worth repairing? The overall physical condition of the amp appears to be very good.
Re: K150-8 smoking...help please [message #22313 is a reply to message #22305] Mon, 02 February 2015 17:50 Go to previous messageGo to next message
pleat is currently offline  pleat
Messages: 1452
Registered: June 2004
Location: Belding, Mi
Senior Member
The amp is worth fixing. I'm not a amp tech, but the smoke may be coming from the 200 ohm resistor that feeds the light bulb. I'd check to make sure it has the 28 Volt bulb. a 12V bulb can cause the resistor to really hot, and may be burning the circuit board. The four blue things you describe are capacitors.
I'm sure Stevenm or Chicagobill can help you.
pleat
Re: K150-8 smoking...help please [message #22317 is a reply to message #22305] Mon, 02 February 2015 23:54 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
Senior Member
Pleat may not be a tech, but he knows more than most techs know about Kustom amps.

Smoke means something is getting hot and I thought the same thing as Pleat regarding the 200 ohm resistor that drops the voltage for the pilot lamp. Do check the bulb and see what the number and voltage rating is.

You can also turn on the amp with the chassis out of the cab and watch carefully to see if you can see where the smoke is coming from. Nothing in the amp should get hot enough to smoke, and I would think that if the problem was transistor related, it would be burning out the fuse.

Check the pilot bulb and let us know what you find.
Re: K150-8 smoking...help please [message #22327 is a reply to message #22305] Tue, 03 February 2015 07:46 Go to previous messageGo to next message
stevem is currently offline  stevem
Messages: 4728
Registered: June 2004
Location: NY
Senior Member
I had a K200B in for repair once that had such a mass of mice living in it that there collective pee ate right through the bottom of the chassis in many spots leaving the power transformer rocking around!!

Unless you back all the circuit boards off the face of the amp to fully check things out you may not fine the root cause of the smoke issue!

Also like Bill posted, the fact that its not popping fuses (if its still the soldered in factory one!) is a good sign in regards to getting to function normal again!

Also many times mice that have had run of a house / kitchen will use steel brillow dish pads for nesting material and once that stuff has arced over it must be steel brushed, or un-soldered from the circuit board tracses, so once again pull it all apart!

[Updated on: Tue, 03 February 2015 07:51]

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Re: K150-8 smoking...help please [message #22329 is a reply to message #22327] Tue, 03 February 2015 08:52 Go to previous messageGo to next message
bmacdo is currently offline  bmacdo
Messages: 14
Registered: January 2015
Location: Florida
Junior Member
Hey, you guys may be onto something. I was thinking the smoke could be coming from the rectangular ceramic looking component just below the pot but the bulb resistor is also right there. So I have the bulb in hand and it says: 6-8V. 0.15A. Seems wrong, eh? Some local guy I called yesterday said probably $200 - $300 to work on this amp...yikes.


I would love to salvage this amp since its by far the coolest looking one I've owned and I was liking what I was hearing out of my Godin Solidac before I started seeing the smoke. This forum is great, what a fantastic knowledge base. The. bit about the steel wool in mice nests was esp. interesting but in my case, the nest material couldn't have been cleaner. It was pure tan fleece like from a dog bed or the inside of a lined winter jacket.
Re: K150-8 smoking...help please [message #22330 is a reply to message #22305] Tue, 03 February 2015 09:30 Go to previous messageGo to next message
stevem is currently offline  stevem
Messages: 4728
Registered: June 2004
Location: NY
Senior Member
the bulb you need is a 1829 lamp, but for now just pull it out and see if the smoke issue goes away!
This bulb can still be had from many electronics supply houses!
Re: K150-8 smoking...help please [message #22332 is a reply to message #22330] Tue, 03 February 2015 10:07 Go to previous messageGo to next message
bmacdo is currently offline  bmacdo
Messages: 14
Registered: January 2015
Location: Florida
Junior Member
Wow, can it really be so simple? With the bulb removed, no more smoking! I'm glad I took the time to open up the amp and clean out all the fleece from the mice before firing it up. I might have burned down the house. You guys just saved me some real $$ since a local tech would've likely reamed me for at least $100 for that bulb change. Thanks so much. My fingers are crossed that something else won't come up but after 30 some years of the amp sitting idle, who knows? In the meantime, I've ordered the correct bulb. Thanks again for your diagnosis.
Re: K150-8 smoking...help please [message #22338 is a reply to message #22305] Tue, 03 February 2015 12:55 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
Senior Member
Another one for Pleat! That bulb is probably a #47 lamp for a Fender amp.

In defense of us local techs, if you had called me and said it started smoking, the first thing that I would have told you was that the amp is old enough, so if it wants to smoke it can smoke. All you can do is point out the hazards involved in taking up bad habits and hope for the best.

Seriously, smoke could be a sign of a hundred different problems. Until you open up the amp and test a few things you can only guess at what might be wrong, some of which are expensive and some not so much. So an estimate of $200-$300 isn't out of the question. Now if you had him work on it and he charged you $200 to replace the bulb, then I might feel burned.

Most of us here have owned and played Kustom amps for a long time now. We've all seen a lot of problems before, so our knowledge base is fairly expansive. Most of us freely share our experience and knowledge with anybody that asks for it, just for the love of these old amps. So please, try and keep your comments about getting "reamed" by a tech to facts and not just a bunch of generalizations.
Re: K150-8 smoking...help please [message #22339 is a reply to message #22338] Tue, 03 February 2015 13:22 Go to previous message
bmacdo is currently offline  bmacdo
Messages: 14
Registered: January 2015
Location: Florida
Junior Member
My apologies, I didn't mean it to sound so snarky. A lot of that comes from living in Florida which is something of a magnet for rip-off artists and unscrupulous players, just the way of it. The guy I talked to is probably above board and was just making the same point you did, that it could be so many things it might cost hundreds to get to the bottom of it. I'm so happy for the easy fix.
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