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Mitsubishi DA-A10

I am considering changing the capacitors in this amp I picked up. I am not electronically trained, but I am relatively handy having built my own house when i had more time many years ago, and graced with lots of curiosity. I realize professionals exist for this purpose, but the cost/benefit ($250-300 for the recap) for the application of this amp isn't that attractive. Looks like about 14 capacitors- about half Elna and the others Rubycon. I did some research and lots of love for Elna Silmic capacitors but cannot find all of the voltage/uf ranges that are in the existing amp. Between Nichicon and Elna I think I can get it covered- but if Elna has the best sound preference would be to do it right. Plan to replace them all regardless of good or bad since I don't know how to test. I do have a multimeter. I suppose if I get a bad new one I will need to do some testing and may cross that bridge then.

So now to my here is my question- two of the capacitors 80V 470 UF have three leads- +, -, and NC. I have researched what the NC means, but haven't found suitable 3 leads on line. Any help appreciated.

Please, if the response is "stop being an idiot and take it to a qualified technician", that isn't going to happen as I am curious about how this stuff works. I understand as professionals if you prefer not to contribute. Thanks in advance.
128x128ovinewar
13 responses Add your response
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ovinewar's avatar
ovinewar OP
172 posts
 
Thank you viridian. I have both the f-20 and the f-10, as well as a c20 and agree the tuners are great. The Nikko isn't a cap issue- most likely something simple in an open circuit that will not allow it to lock on a station.  I am not going to put too much effort into it- I just dont like to trash things that are vintage and well made. 

 I have several vintage Mitsubishi pieces- 4 amps and accompanying pre's and tuners. In my uneducated opinion, they are really well made and sound fantastic. The amps had funky speaker connectors but I discovered an easy upgrade to banana posts that looks factory. I drive Vandersteen's vertically biamped with 2 da-15's and they sound incredible to me. I am weak on sources. I have older CD players but need to upgrade or consider a streaming device. Any suggestions sub $500-700 used is welcome. 
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ovinewar's avatar
ovinewar OP
172 posts
 
No progress thus far. It has a bajillion capacitors! They all looked pretty good. Issue is it will not tune on a station. I have been googling but havent found a good solution as of yet.
imhififan's avatar
imhififan
2,181 posts
 
Congratulations!
Please tell us more about the progress of nikko tuner.
ovinewar's avatar
ovinewar OP
172 posts
 
So finished everthing today and fired it up using the variac. The sound was unbelievable. Even my wife- who isnt that interested, said it sounded great. Could be she was reacting to my ear to ear grin, but it really sounded good. I assume when caps burn in it will improve. Thanks to all. 

Now takling an old Nikko tuner!
ovinewar's avatar
ovinewar OP
172 posts
 
Thanks of all the advice. I ordered an inexpensive variac as I am going to tackle few more pieces of vintage gear. Too late on the methodical approach. I have already replaced the caps on both sides. Appreciate the manual. I had tracked one of those down before I started. I wont fire the amp up until I get the variac. Thanks again
imhififan's avatar
imhififan
2,181 posts
 
ovinewar,
If you haven't download a service manual, here is one:

https://www.manualslib.com/manual/1181997/Mitsubishi-Da-A10dc.html#manual

viridian already give you some excellent advise, I just like to add some of my personal experience working on vintage gears:

Frist step is power up the amp by using a variac or dim bulb tester as viridian suggested, if the amp is working, then go ahead to re-cap. you can use higher voltage rating capacitor but not lower.
Take some picture before you do anything, recap one channel first, test it make sure it is working then recap the other channel.
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ovinewar's avatar
ovinewar OP
172 posts
 
So I knocked most of these out in a flash. Good quality solder and a sucker tool was my best friend. Two of the caps were difficult to see when on the board but now realize they are non polarized. I didnt take them out as I have no replacements. 

I didn't see Nichcon FG, which I used everywhere else,  having non polar caps. I need a 33uf 25v and a 22uf 25v. Any suggestion? 

Also, some additional insight into this statement would help.

" Should any of those caps be used in the signal path for coupling then they will make a larger difference and they should be replaced with a film cap, or if the film cap in the original value, is too large, use a film cap as a bypass on the electrolytic."

Thank you in advance. 
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ovinewar's avatar
ovinewar OP
172 posts
 
Thank you for your response. It doesn't look that daunting- now that I have it opened up. I am excited about tackling it. I will post pics here of the insides if people are interesred. I think I will also change out the horrible speaker posts. Again, thank you Viridian. 
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