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Marantz 2270 Rebuild Help

H

H.V.S.

New Member
I'm right in the middle of my first full recap: my Marantz 2270. I used an importable BOM to order caps and I've been following some previous journals of 2270 recaps (particularly this one http://www.audiokarma.org/forums/showthread.php?t=459591 ). I just got to the phono board, and some info doesn't line up. The main electrolytic cap on mine (a late 80XXX serial number) says 100uf 50v, while the replacement I got says 220uf 50v. I though uf had to be an exact match? Also, all the caps (both electrolytic and film) at the left end of the board (viewed from the bottom) don't look like what I've seen in pictures. There very small balls instead of large films and small electolytics. Are they replaceable anyways?
I'm sure this is all very hard to follow, I'll try to post some pictures later. Anyways, any help would be greatly appreciated, thanks!
 
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Oh, also, I have "fairchild diodes" that are supposed to go on the phono board. what do these replace and is it nescessary?
 
Are you saying 100uf cap is replaceable with 220uf cap, or that the diode looking capacitors are replaceable with regular capacitors? thanks for your reply.
 
Increasing the local filter from 100uF to 220uF may reduce the hum from the phono stage.
I also replace H709 with 2 1N4448 or 2 1N4148 diodes in series. If H707 and 708 are epoxy types, I replace each of them with 1 1N4448 or 1N4148 diode.
If H705 and H706 are 2SC458 types, replace them with 2SC2240BL or KSC1845 types as the originals get noisey over time.
This thread may be of help.
http://audiokarma.org/forums/showthread.php?t=391498

Tom
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Thanks so much. Two last questions. The diodes and transistors are in packages that say "observe caution for handling electrostatic sensitive devices", what precautions do I need to take? and also, can I replace the funky caps at the bottom of the board as if they were regular ones? thanks guys, I'm real excited about this.
 
Here is a picture of the phono board of my 2245 after I replaced the components as per Catrafters suggestions. I have marked everything that I replaced.

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I used a 100uf 50V capacitor as I had one available, I will eventually replace it with a 220uf 50V.
 
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just installed the three diodes. I want to make sure I installed them correctly. I oriented them such that the black line faces the arrow ( or the direction that the green dot on the old diode used to be facing). Is this correct? thanks, I'm almost done! :music:
 
Hi guys, Time for the DC offset and bias settings!
Where can I locate the adjustment locations and test points? I know the specific names (such as J576) but I don't know where to look for these inside the amp.
Thanks! cant wait to fire this up!
 
dc offset is usually speaker connections ... bias will be on driver/main amp board near the big resistors ..
will be a post on the board .
the preset trimmers are white and round shape with square shape on top .
 
yes one lead on each .. be very steady and very slow turning the presets if you need to turn them at all ...they can be very sensitive .
set meter to mv dc .. should tell you in manual .thought i would mention it anyway
 
You say your 2270 sn is >80000

From the Marantz Service Manual Error thread:

2270 SN>3900 Idle current or bias adjust:
Meter set to read DC mV, connect from J754 to J760, set R763 for 10mV

You may want to go trough that thread for other changes
 
Everything working great except....no sound out of phono! I probably put the diodes in backwards, fix it in the morning.
 
From your pic, the diodes look ok. It looks like you have the replacement
transistors oriented correctly too, but you verify that again.
Check the input and output wires.
 
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