Hi all,
well sure enough I got a huge package in the mail today; it wasn't as big as my Sansui QRX-7001 but damn close to it. It was my friend's old Marantz 4270, he just is giving up on it. He complained that it was all crackly and didn't work unless you cranked the volume, well it looks like nobody ever cleaned the 70s man cave out of it, so I Deoxited the hell out of the pots and sliders and at the same time dunked the knobs and face in the sink. So far so good, at least on headphones - so I guess that means if the headphones work but I have issues with the speakers at low volume, it's going to be related to the relays.
But here's the thing. If I plug the headphones into the rear jack, even in 2 channel mode, I have a significant signal on LR. Looking in the unit from the underside, there is a small board that connects to the "power mode" switch and it looks like the largest capacitor on that board done blowed up. It's still there, but wobbly and bulgy. So I'm guessing the repairs should start there. Given the issue that I mentioned, are there any other areas that I should be looking at, or basically just start at the power mode switch and methodically recap each board until it works right?
Edit: after downloading the manual, it appears to be "B.T.L Phase Inverter Assembly PM01" and the blowed up cap is CM05.
This is going to be a back burner project as I need another quad unit like a hole in my head, but at the same time it's got too much potential to just shrug and give up on, or run knowing it has issues and possibly blow it up. If the hive mind thinks there's a chance that recapping just that one board will bring it back to proper operation I'm willing to try it... need an excuse to order from Mouser anyway.
Also, question: my 2220B had nice stainless hex head machine screws holding the face on, but this looks to have (used to be) chrome plated regular old JIS screws. Is that correct for this model?
well sure enough I got a huge package in the mail today; it wasn't as big as my Sansui QRX-7001 but damn close to it. It was my friend's old Marantz 4270, he just is giving up on it. He complained that it was all crackly and didn't work unless you cranked the volume, well it looks like nobody ever cleaned the 70s man cave out of it, so I Deoxited the hell out of the pots and sliders and at the same time dunked the knobs and face in the sink. So far so good, at least on headphones - so I guess that means if the headphones work but I have issues with the speakers at low volume, it's going to be related to the relays.
But here's the thing. If I plug the headphones into the rear jack, even in 2 channel mode, I have a significant signal on LR. Looking in the unit from the underside, there is a small board that connects to the "power mode" switch and it looks like the largest capacitor on that board done blowed up. It's still there, but wobbly and bulgy. So I'm guessing the repairs should start there. Given the issue that I mentioned, are there any other areas that I should be looking at, or basically just start at the power mode switch and methodically recap each board until it works right?
Edit: after downloading the manual, it appears to be "B.T.L Phase Inverter Assembly PM01" and the blowed up cap is CM05.
This is going to be a back burner project as I need another quad unit like a hole in my head, but at the same time it's got too much potential to just shrug and give up on, or run knowing it has issues and possibly blow it up. If the hive mind thinks there's a chance that recapping just that one board will bring it back to proper operation I'm willing to try it... need an excuse to order from Mouser anyway.
Also, question: my 2220B had nice stainless hex head machine screws holding the face on, but this looks to have (used to be) chrome plated regular old JIS screws. Is that correct for this model?
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