Marantz 2270 BOM

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pjf610

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Joined 2017
#1
Hi all,getting ready to start another project a 2270, I am in the process of putting my BOM together and take a look at these main cap's the unit calls for 9000uf 55v these are not even close, what do you guys suggest to use??? This should be a challenging project!!!!
 

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#2
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#5
You need a second tape-spool. (I love creative recycling.)

Yes, modern caps can be far smaller than the old stuff. Hey, my old Thunderbird got 148HP out of 5.7 liters 650 pounds, my new(er) Honda has 149HP out of 2.5 liters and ~~200 pounds.
 
#6
Hi all, still working on my BOM for this unit. All the Cap's are ordered and on their way , These transistors that I am trying to find replacements for is a bit more challenging, it seems some of the cases that was used back then you can no longer get anyway any help would be appreciated this is what I am looking for:
Replacement for

2SA640 M-l
2SC945 Q
2SC735 Q
2SC484 R-Y
2SC680 B
2SA566 B
2SC984 B
2SA562 Y
This receiver is in pretty sad shape and I am planing to give it a total over haul
 
#7
Any time in the past 10 years I have recapped an older commercial piece of equipment the new electrolytics are smaller than the old for the same value.
Even if you could buy NOS, New Old Stock, caps that were the correct size for those clamps I would not recommend using them because they are old and they may have changed chemically.
Change the damn clamps!
 
#8
I've experienced the same trouble sourcing transistors for my Marantz 2245. My recommendation - if they are not broke don't replace them.
If you find one that is broke, then you may need to cross refer it to a more modern small signal transistor. When I do this I I find a one with:
1. same footprint
2. same or greater voltage rating
3. similar hfe (gain)
4. intended for audio (usually lower noise)

If I can't find the same footprint I have resorted to reshaping/swapping the leads as necessary.

BTW it is quite easy to test a bipolar transistor even in the circuit using a volt meter with a diode test function. Rather than write a lengthy dissertation here, check this out:
Meter Check of a Transistor (BJT) | Bipolar Junction Transistors | Electronics Textbook.
Using the fact that the base/emitter junction will have slightly more Vf than the base collector Vf means that you can even tell if a unknown transistor is PNP rather than NPN.
 
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