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Marantz 2270 Phono Preamp

Hello all. New to the site. Wonderful uploads of information on here. I recently had someone local repair my 2270. I bought it used at a steal for 50 bucks. Sounded amazing. After about 45 minutes the left channel would just begin to fade out. Then it would pretty much stay out. Had a local guy in atlanta do a good job on it. Got it back and it sounded wonderful. I have had a 4240 for years and this one just blew it away. Well then low and behold the phono amp board starts to give problems. It was only on the phono circuit. I swapped the two inputs around. Same thing. Left channel just goes out after getting hot. Called the guy back he says well i didn't repair the phono board.... Great. So i pulled up the schematic removed the 6 wires and 4 screws. I have it out. I am an automotive tech so i am pretty good with soldering. Problem is i have no idea where to start. There are a few diodes and alot of capacitors on there. And from my understanding the capacitors have to be removed from the circuit to test them. Well if i am to go through all that hassle of undoing them all and any one of them could be bad after heating up i might as well just replace them all.

Thats where i need help! Radio shack is a joke. I went to mouser and that gets really confusing. I have pics as well.



Marantz 2270 Phono Preamp

There is a huge amount of information on refurbishing the 2200 series Marantz receivers on Audiokarma.org. Parts lists, transistor substitutions, upgrades, etc. The phono pre-amp is pretty easy to deal with but there are a few of transistors on the board that ought to be replaced. See http://www.audiokarma.org/forums/showthread.php?t=217343

Marantz 2270 Phono Preamp

Replace the electrolytic caps; those will have values in the .47 to 6800 range (not that high in the phono circuit). You should use the same value, but you can go higher in voltage; if the original was 25 volts you can use 35 or 50 volts.
I recommend Nichicon capacitors; I go to Mouser also. Once you get values and quantity you can just call Mouser and tell them you want all Nichicon; they can look them up quickly.
You must get the polarity correct; the boards are usually marked, but make sure you look first. If only audio is going through a cap the polarity shouldn't make any difference, but if it is DC from the power supply you will have big problems with reversed polarity.
You most likely have capacitor problems; could also be a bad transistor, but this is unlikely.