Klorslug Posted January 3, 2011 Share Posted January 3, 2011 Need some advice with a Heathkit W-5M that I bought from a friend for $50. He bought it at a garage sale years ago and it’s been sitting in his basement ever since. Unfortunatly one of the Mullard sheild logo ECC82/12AU7’s is missing. So I figured while I look for a balanced match the first thing is check out the workmanship, hope for the best and clean out all the dust and dirt. I’m a newbie when it comes to tube gear. Only other tube stuff is a Wollensak Reel2Reel. When I removed the bottom cover plate it looked a lot nicer than I expected…but I noticed a pale yellow, almost flouresent powder on some of the nuts on the power transformer (54-32), the insulation on the transformer wires and mostly on the bottom of the Bass-Bal control. Has anyone seen this before? Oxidation, mould or what. Didn’t want to start brushing or spraying anything till I get some advice, just in case the powder’s a health issue, or I blow up this beauty little amp using the wrong cleaners. Hanx for any input, Jaymz Here’s a picture of what I’m talkin about. (hope I resized it propper) Quote Link to comment Share on other sites More sharing options...
Klorslug Posted January 3, 2011 Author Share Posted January 3, 2011 and a close up. You can see it on the Bass-Ball control Quote Link to comment Share on other sites More sharing options...
Don Richard Posted January 3, 2011 Share Posted January 3, 2011 It's possible that, considering the age, some of the electrolytic caps have gassed out some of their electrolyte. It would be good to check and/or replace all of the caps. Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted January 3, 2011 Share Posted January 3, 2011 The yellowish powder is probably cadmium sulfide or cadmium oxide. This is very commonly seen in vintage equipment, antique radios, etc. I would just leave it alone and not try to clean it off; however, when working on the amp, it wouldn't hurt to wear a dust mask as breathing in the dust (assuming you dislodge any of it) isn't the best thing to do. It, like asbestos, would probably take huge exposures over very long periods of time to cause health issues, although this hasn't been studied as asbestos has. Also, wash your hands well after handling the chassis so you don't ingest any when touching food . I've worked on hundreds of amps and radios with it, and I'm still here! Keep in mind that at the very least, all the electrolytic and paper caps need to be replaced. Don't attempt this unless you have the needed experience. Quote Link to comment Share on other sites More sharing options...
Klorslug Posted January 3, 2011 Author Share Posted January 3, 2011 Thanks for the help. I was afarid it might be a Cadmium deposit from what little I could find on the web. Was hoping there was a safe way to clean it (I have a 2 ½ year old son). As for changing the caps I’ll be asking to my uncle and cousin to help me with that as my soldering skills are sub-par. They’re both electricians and my uncle has lots of old tube gear (mainly radios). Hope he has a tube tester. Before I change the caps, should I power it up after I’ve checked all the tubes to make sure it works? Then I’ll have to figure out what brand of caps to use as I’ve seen many different types in the rebuilts I’ve looked at online. Learnig more everyday. Hanx again, Jaymz Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted January 3, 2011 Share Posted January 3, 2011 Thanks for the help. I was afarid it might be a Cadmium deposit from what little I could find on the web. Was hoping there was a safe way to clean it (I have a 2 ½ year old son). As for changing the caps I’ll be asking to my uncle and cousin to help me with that as my soldering skills are sub-par. They’re both electricians and my uncle has lots of old tube gear (mainly radios). Hope he has a tube tester. Before I change the caps, should I power it up after I’ve checked all the tubes to make sure it works? Then I’ll have to figure out what brand of caps to use as I’ve seen many different types in the rebuilts I’ve looked at online. Learnig more everyday. Hanx again, Jaymz Do not power up the amp before the caps are changed. If any are shorted you could cause damage to the power transformer. Be sure to replace the caps with units having the same, or even higher working voltages. Brand is unimportant. You should be able to find the manual for the amp online which will contain a complete parts list. Companies like Mouser Electronics can provide you with all that you need. Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted January 3, 2011 Share Posted January 3, 2011 Here's the schematic for the amp with clearly delineated parts values. From what you stated, your uncle should be able to read this no problem: http://www.freeinfosociety.com/electronics/schemview.php?id=36 Quote Link to comment Share on other sites More sharing options...
Klorslug Posted January 3, 2011 Author Share Posted January 3, 2011 OK no power till the caps are changed. Thanks for the link to the schematic. I downloaded the assembly manual just after I got the amp and read it a couple times to get a basic understanding of the parts and wiring. Looks like I’ll be buyin some caps and hoping my uncle has some spare time. Hanx, Jaymz Quote Link to comment Share on other sites More sharing options...
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