Buster
Wholenote
Posts: 213
Formerly Known As: Buster Strings
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Post by Buster on Jun 24, 2021 11:06:44 GMT -5
I've got a late 70s (?) Marantz 2285 B stereo receiver. I'm looking to see if there is anyone who can help me with an issue.
Please keep in mind I have nearly zero electronics knowledge.
The right channel intermittently cuts out. Sometimes it just drops out suddenly and completely and sometimes it fades out over 3 to 5 seconds. It can be brought back by playing with the volume knob -- turning it up to about half volume till it pops back in and then lowering the volume. I can let it play for hours and it won't cut out and sometimes it'll drop out three times in 15 minutes.
I've cleaned the stacked volume pots several times, and the speaker relay as well with no change.
Any ideas?
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Post by Opie on Jun 24, 2021 11:12:36 GMT -5
Sounds like a bat pot, spray doesn't always do the trick. Or it might be a bad solder joint on the pot,you can check that using wood chopsticks and gently poke the wires at the conections.
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pdf64
Wholenote
Posts: 556
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Post by pdf64 on Jun 24, 2021 17:15:29 GMT -5
Valve or solid state?
Assuming solid state, a slow fade may indicate a stage’s bias drifting out of whack. Possibly due a bad connection which, when open, allows a cap to charge up, hence the fade (rather than crackle).
I suggest to identify the collector terminal of each stage, and measure its VDC (with respect to 0V chassis common), in both the normal and fault modes.
When a stage where there’s a change can be identified, focus your attentions there.
Alternatively, try just reflowing every solder joint on the PCB.
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Post by guildx700 on Jun 24, 2021 19:11:20 GMT -5
Capacitors also go south at that age, usually everything needs to be gone over or other issues will arise.
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Post by tahitijack on Jun 29, 2021 10:49:57 GMT -5
Buster based on the above you probably need to take the amp to a vintage repair shop. Don't feel bad, all I k ow about electronics is found on my remote control buttons. I know my limits. Good luck, I owned a Marantz 2220b until it was stolen by someone that could not work hard enough and earn the money to afford to buy one for themselves.
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Buster
Wholenote
Posts: 213
Formerly Known As: Buster Strings
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Post by Buster on Jun 30, 2021 16:33:21 GMT -5
I'm actually thinking about letting this one go. I don't have a good electronics repair shop in my area, especially one that works on vintage electronics.
I've got several other receivers of about the same quality and although it's certainly worth repairing, considering what these units sell for in online auctions, I think it's time to downsize my hobby collections a bit.
My wife thinks it's time to do that as well.
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Post by Larry Madsen on Jul 5, 2021 19:44:21 GMT -5
My Marantz 1150 integrated amplifier (circa 1977) has a "reverse" channels knob. Just a two position knob. It has a dirty contact and I will lose one channel intermittently. One day I need to get in there with some contact cleaner and see if I can get it back in order. For now I just run the switch back and forth until I get the channel back ... whenever it goes out.  Edited to add: It does seem that if the over-all volume is up high the channel tends to not drop out as much on me. |
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Post by Peegoo 🏁 on Jul 6, 2021 9:00:47 GMT -5
If it has an L/R balance control--check and clean that too.
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Post by Leftee on Jul 6, 2021 9:01:43 GMT -5
Side note…
I was shocked to see what this old stereo gear fetches these days.
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Post by fkaJimmySee on Apr 17, 2022 13:03:22 GMT -5
Side note… I was shocked to see what this old stereo gear fetches these days. The hipster element that also loves vinyl. I don't get it at all. |
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