Thaddeus Smith Posted August 8, 2019 Author Share Posted August 8, 2019 3 minutes ago, babadono said: If I were going to dig into one of these as deep as you're contemplating I would replace ALL the electrolytic bypass and coupling caps as well as the main filter caps. I would use non polar electrolytics for the coupling caps(probably Nichicon Muse series). But that's just me, I'm anal about this kind of stuff. Your logic is sound. Quote Link to comment Share on other sites More sharing options...
glens Posted August 8, 2019 Share Posted August 8, 2019 4 hours ago, Thaddeus Smith said: Maybe those big blue ones? Has to be, and there has to be the complement at the bottom, I think I see a soldered pad shaped the same peeking out from behind the wire in the way, down below. More capacitance wouldn't hurt in that position, but you'll do well to shoehorn anything you can in there. The bottom caps are undoubtedly "okayer" than the tops... While there's likely at least one screw per board going through the bottom chassis plate I see neither heads nor threads through the back plate. Possibly fastened to the back, at least on the top, by the nut on the RCA jack. Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted August 8, 2019 Author Share Posted August 8, 2019 15 minutes ago, glens said: Has to be, and there has to be the complement at the bottom, I think I see a soldered pad shaped the same peeking out from behind the wire in the way, down below. More capacitance wouldn't hurt in that position, but you'll do well to shoehorn anything you can in there. The bottom caps are undoubtedly "okayer" than the tops... While there's likely at least one screw per board going through the bottom chassis plate I see neither heads nor threads through the back plate. Possibly fastened to the back, at least on the top, by the nut on the RCA jack. Agreed - I've got ample experience with disassembly/reassembly of laptops, tablets, and phones so I have the tools and necessary know-how to methodically pull this thing apart with care. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted August 8, 2019 Share Posted August 8, 2019 36 minutes ago, Thaddeus Smith said: Agreed - I've got ample experience with disassembly/reassembly of laptops, tablets, and phones so I have the tools and necessary know-how to methodically pull this thing apart with care. Then you know that it's easiest to discharge the caps on your tongue. 1 Quote Link to comment Share on other sites More sharing options...
glens Posted August 8, 2019 Share Posted August 8, 2019 1 hour ago, Thaddeus Smith said: I've got ample experience with disassembly/reassembly of laptops, tablets, and phones so I have the tools and necessary know-how to methodically pull this thing apart with care. Not me, I've never taken anything apart (wink, wink). 42 minutes ago, CECAA850 said: Then you know that it's easiest to discharge the caps on your tongue. I only do that to confirm when I thought I'd already discharged them but can't remember. You'll know whether it's safe to touch the leads with your bare fingers! Quote Link to comment Share on other sites More sharing options...
glens Posted August 8, 2019 Share Posted August 8, 2019 I wish I'd had a camera with me the day years ago I was visiting the folks and went with dad to an old farmer's place to get a load of firewood. The farmer had a book of matches with the flap stuffed behind the matches in his shirt pocket. I know this because I could see the match heads all in rows through the burnt-edged hole running across the front of the pocket, right in line with the heads. Someone gave a shout out to Darwin earlier today in another thread, that and this made me think of the old farmer. But maybe he disproves Darwin's notions? Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted August 18, 2019 Author Share Posted August 18, 2019 OK, decided to crack into this today. The chassis cover comes off easy peasy, then it's 2 screws on the bottom and two screws on the top for each amp module. All wires to each module have quick disconnects (4 total), so it's really not too bad. Here's a photos of each side, along with the caps currently installed. I haven't gone so far as to separate the board from the heat sink. The toroidal power supply in this thing is MASSIVE. Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted August 18, 2019 Author Share Posted August 18, 2019 Looks like about $200 in parts if I go with Nichicon: https://www.mouser.com/ProductDetail/Nichicon/LKG1K103MKNF?qs=sGAEpiMZZMsh%2B1woXyUXj5obA%2BPF%2Bvy7%2FksR%2Fohmnlk%3D Mouser doesn't seem to carry 10,000uf Elna caps. Finding them on ebay though: https://www.ebay.com/itm/1-5pcs-ELNA-10000UF-80V-FOR-AUDIO-35-50mm-Audio-Filter-Electrolytic-Capacitor/113837328449?hash=item1a813bc841:m:mDzf4G32cIjowNEFyz5uvQw Thoughts? Edit - looking at those nichicon caps and they come in three different sizes, the smallest of which is 40mm in diameter and 68mm length. The currently installed caps are 35mm diameter and 50mm length - a rough measurement of the remaining boards shows about 12.7mm of clearance between the top capacitor and components of the adjoining board module. So these likely won't work. Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted August 18, 2019 Author Share Posted August 18, 2019 Here's another source for what's currently installed, but I haven't much experience with ebay sellers out of china for caps and no idea if they're legit? You guys have any experience there? https://www.ebay.com/itm/173601230275 Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted August 18, 2019 Author Share Posted August 18, 2019 I'm seeing lots of threads about shady/fake capacitors procured via ebay out of China. Years worth, especially when it comes to these larger values used in older amp topologies. I've managed to find nichicon's in the 35mm x 50mm size with the appropriate values and am just going to have to deal with the lead time and price for the sake of piece of mind. I checked Digikey and they don't have any in stock either. I guess my only concern now is that these appear to be snap in types, and I'll be soldering. https://www.mouser.com/ProductDetail/Nichicon/LKS1K103MESC?qs=ppWA7IX8Fw58e%2Fx4ufs4wA%3D%3D Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted August 26, 2019 Author Share Posted August 26, 2019 Options seem to really open up at places like Mouser when you don't refine by "audio grade" capacitors in these values and size constraints. So what's the risk with using plane Jane caps vs those designated as "audio grade"? Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted August 26, 2019 Author Share Posted August 26, 2019 Audio Grade: https://www.mouser.com/ProductDetail/Nichicon/LKS1K103MESC?qs=ppWA7IX8Fw58e%2Fx4ufs4wA%3D%3D Normal: https://www.mouser.com/ProductDetail/Nichicon/LLS1K103MELC?qs=sGAEpiMZZMtZ1n0r9vR22TrbYqu733AyP8H3CesvQsc%3D Quote Link to comment Share on other sites More sharing options...
babadono Posted August 26, 2019 Share Posted August 26, 2019 "Snap in" is just to hold cap in place until soldered. Helps in manufacturing of wave soldered boards. Just make sure the lead spacing is correct. And the overall size will fit unto your boards of course you knew that. Audio grade vs. regular? Hmm.... If audio grade makes you warm and fuzzy go for it As to counterfeit parts from China....first of all they're probably all from China anyways. There are some Elna audio caps on the Ebay page that you linked, sure wish they would give the complete P/N Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted August 26, 2019 Share Posted August 26, 2019 I would use multiple clusters of caps wired in parallel. Anything less and you're wasting your time. 1 1 Quote Link to comment Share on other sites More sharing options...
babadono Posted August 26, 2019 Share Posted August 26, 2019 Curiously Elna catalog does not show a LAO series 10,000uF 80 volt cap..Hmmm...old catalog?....or are the parts on Ebay counterfeit? Quote Link to comment Share on other sites More sharing options...
babadono Posted August 26, 2019 Share Posted August 26, 2019 Found a post on some part website: https://theaudiocrafts.com/elna-10000uf-80v-andquot-for-audioandquot-lao-series states as of 2014 and after all Elna caps are made in China. These "look" legit:https://www.ebay.com/itm/1-5pcs-ELNA-10000UF-80V-FOR-AUDIO-35-50mm-Audio-Filter-Electrolytic-Capacitor/113837328449?hash=item1a813bc841:m:mDzf4G32cIjowNEFyz5uvQw Quote Link to comment Share on other sites More sharing options...
babadono Posted August 26, 2019 Share Posted August 26, 2019 So no other big caps up by the transformer? Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted August 26, 2019 Author Share Posted August 26, 2019 2 minutes ago, babadono said: So no other big caps up by the transformer? No sir, not that I could see. Just quick disconnect harnesses for all of the modules and wiring for the front panel switch/LED indicators. On the modules themselves it's just the two big'ns and the three smaller ones between the fuses. 5 minutes ago, babadono said: Found a post on some part website: https://theaudiocrafts.com/elna-10000uf-80v-andquot-for-audioandquot-lao-series states as of 2014 and after all Elna caps are made in China. These "look" legit:https://www.ebay.com/itm/1-5pcs-ELNA-10000UF-80V-FOR-AUDIO-35-50mm-Audio-Filter-Electrolytic-Capacitor/113837328449?hash=item1a813bc841:m:mDzf4G32cIjowNEFyz5uvQw Yeah, I have those on my watch list. The problem is just that I don't really have enough experience with this stuff to know by appearance whether or not they're legit once I have them in my hands. I also don't have suitable test equipment to measure them and ensure they are within spec - so I feel compelled to buy through Mouser or Digikey. Probably all coming out of the same factory, but it just seems like a better purchase vs. random Ebay sellers. 39 minutes ago, babadono said: Audio grade vs. regular? Hmm.... If audio grade makes you warm and fuzzy go for it It's just a distinction that's clearly made on the parts suppliers' websites, so I'm certainly curious what it is about their construction or specifications that designates them as such, since it does dramatically reduce the pool of options. I probed ATI support a bit further. Still no luck on the schematics, but they did indicate I've got some wiggle room in cap values. I need to stick with 80v, but could probably drop down to 8,200uf without noticing much difference over my degraded 10,000uf caps. So there's that. Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted August 26, 2019 Share Posted August 26, 2019 Sell it. Buy 3 more chickens. Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted August 26, 2019 Author Share Posted August 26, 2019 6 minutes ago, jimjimbo said: Sell it. Buy 3 more chickens. I know you're kidding, but I've wanted an ATI from this era ever since I borrowed Carl's 1502. It's worth doing a bit of a refresh, even if the original "deal" I got has been less than stellar. Quote Link to comment Share on other sites More sharing options...
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