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Picked up a Rough KX-100 Tube Amp - Will need some guidance

rufleruf said:
Tim, My local electronics store has a tube tester and it is so crazy worn with loose pins and lack of maintenance that everything I test comes out bad. Just a warning....
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Thanks. I'll beware. He's been in business for 50 years. Don't think he'll be around much longer. One of the old guys that still deals in tubes. Says he's got 1 or 2 thousand tubes in inventory.
 
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Sounds about right. I figured it was their sales plan - if all tubes test bad, everyone buys some.
 
Did some more cleaning tonight. Found that the source selector switch S1 had two wires disconnected and electrical taped together. That can't be a good sign.

Was using Brasso on the knob brights that I still have and they are cleaning up nice. Also used Brasso on the faceplate and that certainly made it look much better. I'm being careful to not remove the stenciling. Tried using Brasso on the corrosion on the chassis and that wasn't cleaning up so easily. It also appeared to start fading the stenciling. Cleaning up the chassis is going to be a challenge.

Looks like I can add the following to my list of needs.

Fuse cap
S1 source selector switch (maybe).
 
Question for the experts.

Any recommendations on what size and where to get a Variac? I see one from PE that's 3A. Is that enough or should I go for 5A? Any that I should stay away from?
 
Can you post a picture of the source selector switch? If it turns it should be fine. Wires can be soldered back together easily enough.

The chassis cleaning is a hard one - I'd say plan on getting a case. Brasso seems to have a lot of ammonia in it if the smell is any indication, so maybe try the ammonia scrub mow.
 
rufleruf said:
Tim,

Brasso will make the knob brights look pretty good. Others may object but I have used it on faceplates too and it seems to do a pretty good job on stains without attacking the lettering. Per the sticky about cleaning a Fisher, somewhat heavy duty ammonia applied with a stiff toothbrush and some patience will remove some chassis oxidation. I recommend working outside on this. Just buy a cabinet if it's too ugly for you once you have exhausted your cleaning options.

Nice score on the KX100 manual. I've been casually looking for one for a while with no luck.

In my experience the Telefunken 12ax7's are almost always good, you might just go for it until you get a tester.

BTW - what color is the jewel on your faceplate? Mine has a non original red LED and I've been wanting to replace it.
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rufleruf,

Took those 12AX7's in and got them tested. There was seven of them and they all tested good. You were right. That will cover me for the low power sections. When I get close to testing I'll have to make a decision as to the power tubes in the output.

Ended up testing all of the tubes I had on hand in my basket case Fisher 500B. All the tubes including those seven 12AX7's and excepting for three 6au6's tested good. The 6au6's showed a "short". but otherwise showed good. I bought replacements from the parts store as a thanks for the testing.
 
audiodon said:
Check out the stickies at the top of the forum for answers.
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Thanks audiodon,

I'm going through the stickies and I saw your one about deep cleaning a tube amp. Just love that one.

I'm hesitant to use wet cleaner on it, but I'll test some various means to get at the splotchiness on this rough looking chassis. I don't want to lose the stencils if at all possible. All the loose stuff has been blown off. Now it's time to really clean it. Brasso isn't touching it - next I'll test some stronger ammonia solution to see if that does better.
 
Tim. If it's dirt, and general grunginess, I use Scrubbing bubbles and a brush. Then rinse it off with 91% Isopropyl, and finish off with CRC QD Electronics cleaner. Get's the dirt off, and leaves the lettering. As the chassis was cadmium plated don't expect 56 buick grill chrome look. It has a semi dull look to the finish. And stains are extremely hard to get out. I found I'm allergic to Ammonia in the bottle, although if I wear gloves I can use brasso and other metal cleaners. Probably the least offensive while being an effective cleaner is BLUE MAGIC metal cleaner/polish. We use it on the brass on the sub in Baltimore Harbor, and you can imagine what the brass on the boat looks like after a week of grubby visitor fingers touching. It'll get the heavy oxidation but you have to work at it, so you can throttle the elbow grease to get the finish you want.
 
larryderouin said:
Tim. If it's dirt, and general grunginess, I use Scrubbing bubbles and a brush. Then rinse it off with 91% Isopropyl, and finish off with CRC QD Electronics cleaner. Get's the dirt off, and leaves the lettering. As the chassis was cadmium plated don't expect 56 buick grill chrome look. It has a semi dull look to the finish. And stains are extremely hard to get out. I found I'm allergic to Ammonia in the bottle, although if I wear gloves I can use brasso and other metal cleaners. Probably the least offensive while being an effective cleaner is BLUE MAGIC metal cleaner/polish. We use it on the brass on the sub in Baltimore Harbor, and you can imagine what the brass on the boat looks like after a week of grubby visitor fingers touching. It'll get the heavy oxidation but you have to work at it, so you can throttle the elbow grease to get the finish you want.
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My wife has lots of cans of scrubbing bubbles scattered through our 3 bathrooms and kitchen. I'll give it a try, but... I'm concerned that the cadmium layer and surface are etched. Seems that these amps were exposed to rain or something on the outside. They are very splotchy and I tried Brasso and it only touched it a little. If it was a dirt layer it would have come right off - I'm pretty sure. I'd love to just clean it and put it into a nice case, but I'm getting scared at the prices for wood cases that will fit this unit. I've got a KM-60 that must have been matched to it and a 500-B that was the reason I picked up all 3 units. They all have the same issue with the surface of the chassis.
 
Bets are the cadmium plating is etched, with the splotchy surface. About all you can do with minimal or no effect to the lettering is to use the scrubbing bubbles procedure. About the only thing that will bring the chassis back to an even looking surface is to strip the chassis of all topside parts, then go at it with abrasives and polishing gear. You end up with a highly polished chassis but no lettering.

If you mask all the sockets, and trannie's after cleaning, you can seal the chassis with a couple coats of a clear. Use a rattle can semi flat or satin finish for more authenticity. Full gloss will look funky with the splotches. If any of the lettering comes off go down to the hobby shop that carries HO scale or N scale model trains. They usually have dry rub off transfer lettering. All you have to do is match size and font as close as possible, which is easier said than done. apply these before the sealant so they are locked in.

I'm not that keen on bringing one back to factory (just out the door look), just clean it up with minimal change to the actual parts and chassis. I did a 400 for a guy(strip and polish, lettering, seal), and boy did it cost him. Had something like 15 hours, stripping the parts off, cleaning, polishing, applying lettering, and then sealing it with clear. All this on top of a full resto underneath and I was about ready to throw in the towel on these. Any nicks, marks, splotches, funky striations in the cadmium, etc. I consider to be war wounds from 50+ years of use or abuse. As long as the Front panel is decent and the chassis isn't rusted to hell and back, I leave it out of a case. If it came with a case, I'll put it in the case.
 
I concur with Larry - I've tried a bunch of different approaches to the oxidation you describe, and just cleaning as best as can be done and living with it is probably the best course. Whatever you do, don't rattle can it silver! I have an X101C that the bottom plate was painted and it rally cheapens the look. Patience will turn up a cabinet for it.
 
Tried the Scrubbing Bubbles and it didn't do a whole lot, but at least it isn't terrible on the stenciing. I could see that with repeated applications and wiping where it would take the stenciling off, but it takes some work before that happens. I also tried something new. It removed the corrosion, but it took the stenciling right off too. It's Krud Kutter from Wally World. It worked on the splotches and removed the rust. It's a bit time consuming, but since this is in such bad shape, I'm not surprised. I followed it up with a little Brasso and it doesn't look too bad. I'll have to mask-off the stenciling before hitting it with this tuff, but it seems to do the trick. It has an order to it as it has a chemical reaction. It contains Phosphoric Acid and you can smell the chemical reaction. Don't do this in an enclosed space and read the directions.

I circled a heavy rust spot in blue below. It is much lighter after the Krud Kutter. Is this the way to go? Maybe. I'm going to keep going with it after I mask off the stenciling. It might work on the RCA jacks too - they have heavy rust. I'll do a few more applications the area in red to get it looking better and then move on across the chassis.

Note that the rivets for the V1 socket had heavy rust and now they are a bit shiny. It cleaned up the rust pretty well on those rivets.


IMG_2670.JPG IMG_2669.JPG
 
A while back, someone mentioned painting the chassis with Krylon Brushed Metallic Nickel Satin. I tried that, didn't really like it, and ended up using Krylon Metallic Silver. Results shown below. Of course, being a solid state unit, there is no lettering. The painted surface is a bit fragile and will scratch easily. It is also non conductive, so any parts that need chassis connection will need to have the area around the hole scraped.

1601
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1602
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fred soop said:
A while back, someone mentioned painting the chassis with Krylon Brushed Metallic Nickel Satin. I tried that, didn't really like it, and ended up using Krylon Metallic Silver. Results shown below. Of course, being a solid state unit, there is no lettering. The painted surface is a bit fragile and will scratch easily. It is also non conductive, so any parts that need chassis connection will need to have the area around the hole scraped.
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Looks really nice. I can't tell that is paint. Not sure I want to go down that path as it would require drilling out all the rivets on the chassis. Wish I could get it looking that good, but I'm not going to go down that path because of the effort and time involved.
 
Masked it all off tonight. I'll start the cleaning with Krud Kutter tomorrow. In the meantime I cleaned the original cord. the plug has the Fisher logo on it. It came out looking decent. The Krud Kutter brightened up the copper spades too.
 
I use mouser for 99% of my caps. Make one big order then your shipping isn't too bad to swallow! They do have economy shipping which is UPS dropping it off a teh local USPS distribution center and then USPS handes the delivery. Take about 4-5 day to get to Baltimore. Priority mail isn't any faster and $3. to $4 more. NNICHICON UPW, UHE Series for the power supply 'lytics and UKL for any other 'lytics.
 
larryderouin said:
I use mouser for 99% of my caps. Make one big order then your shipping isn't too bad to swallow! They do have economy shipping which is UPS dropping it off a teh local USPS distribution center and then USPS handes the delivery. Take about 4-5 day to get to Baltimore. Priority mail isn't any faster and $3. to $4 more. NNICHICON UPW, UHE Series for the power supply 'lytics and UKL for any other 'lytics.
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I'm finding it hard to figure out which caps will fit in the original cans at mouser. Their search interface isn't particularly helpful. I can find capacitance and voltage, but not dimensions. Any suggestion on what to get that will fit in the original cans? Anyone stuffed their own and have a parts list? I'd like to just stuff the old cans and epoxy them back together if possible. My fallback position is to get some from one of the rebuild kit guys, but I'd like to stuff my own if possible.
 
When you do the search and scroll down to see the individual caps, most of the time the dimensions in mm are right n the box where the value and voltage is, I think it's the 4th or 5th box from the left side.
 
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