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It looks like the selector swtich's bearing in the front panel of my M3A is frozen! Has anyone ever heard of this one? This selector is designed as follows: Round Black selector switch knob is scewed onto the 10.5 inch silver shaft with a tiny hex screw. This silver shaft runs front to back. There is a copuler at the back of it inside the unit that connects the silver shaft to the shorter shaft protruding from the selector switch itself. The connector is a cylindrical female coupling with two 7/64 inch hex screws. One screw clamps the front side of the coupler to the rear of the silver shaft, the other screw is in the other side of the coupler which slides over the short shaft protruding from the selector. The selector switch itelf is horizontally mounted against the vertical circuit board in the rear of the unit.I was able to identify the problem by loosening the 7/64 hex to the silver shaft. Turning the coupler can then turn the selector switch shaft. When I then reverse the torque, tighten the coupler on the silver shaft and loosen the selector switch side - the silver shaft won't budge without some some scary serious effort using pliers.
Of course AI wants me to send the unit to them. Unfortunately I dont have the time or the money to do so.
Does anyone know how this silver shaft mounts to the front pannel and/or the bearing?
I don't have experience with bearings, but if I could get access to it, is there any chance a lubricant, compressed air, or WD40 might free it up enough to use?
If I could get it out, I wonder if I can get away without using a bearing. I bet I could rig something up. I just need to decipher how to get to it.
Right now I have 2 inputs working: Tape In for my Phono and whatever the selector is pointing to, DAT I think. Unfortunately I need at least 3 inputs to cover everything so I've got to figure a way to get the selector to work again.
I hope I provided enough information for you to picture what the issue is, please do share your thoughts. I'd really appreciate it.
There's way too much voltage in there for me to make a habit of changing inputs by reaching back and just turning the selector. Once I touched one of the heat sinks while she was fired up. Surprise THEY ARE HOT! I will never do that again (ouch).
Thanks, John
Edits: 01/28/16Follow Ups:
I put her on the bench this afteroon. Took the Selector knob off (1/16 inch hex); Loosened the coupler (7/64 inch hex), and selected a wrench to loosen the knut on the front of the unit (under the selector knob position). I found my 7/16 inch wrench and gently started to loosen it. As I did so I noticed the entire shaft started turning. A quick check showed this solved the entire problem!
My earlier diagnosis of a "frozen bearing" came directly from Audible. Gosh what a waste of time and money that would have been if I sent her in. She's working fine now, thank you all for your great suggestions and help. I hope this post will help another down the road. John
I took the top off my M3A, 1997 vintage.
My selector switch uses a 1/4" brass rod.
Their is a bushing on the front end near
the knob that is mounted using a nut. I
would spray some PB Blaster where the rod
goes through the bushing. When it breaks
free I would loosen the front coupling set
screw and remove the rod and knob. I would
consider replacing the rod with a brass one
as aluminum corrodes as you found out. If
you don't replace the rod use some 400 grit
sandpaper to dress up the rod. Or you can
swap it end for end to get a new bushing contact
point.McMaster-Carr or a good hobby shop will have
1/4" brass rod.Jerry P
Edit: It occurred to me that if you remove the
bushing nut and loosen the coupling set screw
the knob, shaft and bushing could be removed.
This would make it easier to use some PB Blaster
and some heat on the bushing if needed.
Edits: 01/31/16 01/31/16
There's a product called PB Blaster what has worked for me on many old restorations when problems as you describe happen. Spray it, let it work and don't force the issue and you will be rewarded.
HA
Thanks I've got some on the shelf.
?
$$$, downtime, and its my nature to diy if I can.
I should acknowledge my conversation with AI service manager. I voice concern about super long waits to get work done by them. He assured me that things have changed. They could have it on bench in a day or two. This job was expected to take him less than an hour.
I have owned AI since 1998. After purchase service from these guys has been a nightmare. They have changed?????
Oh, you confused me :) I read I owned . . . and i thought "is this Art?".
Anyway they indicated that "things have changed". I have no experience or any further anecdotes about that. Like I said, I want to try to fix this myself.
Wow, great ideas. Thank you to all. I will dive into it this weekend. I really appreciate your help. Hope I can return the favor soon. I'll keep you posted.
John
you can do this - but it will require a lot of work- removing the face plate and disassembling part of the chassis-
If you feel you are up to the work it can be done-
If the shaft is 'silver' then it is aluminum - as opposed to the Brass that was also used. Aluminum can corrode and create quite a problem when it does- expansion - which leads to binding in the bushing on the front of the chassis - and the corrosion byproduct is AluminumOxide - the second best abrasive compound after SiC...
I am more Familiar w/ the M3, than the M3a-
however if you want more help- PM me-
Happy Listening
There is a "bushing" in the front panel that the long shaft rides in (hard to say if the bushing is part of the shaft assembly). If the shaft is frozen in that bushing you might be able to free it by squirting a little lubricant (WD-40 etc.) into the bushing.
You can see the back side of the bushing with the lid off. With the knob off you could try squirting the lub from the front/panel side too. Let it sit for awhile and hopefully it will loosen. Unplug first of course. :)
Good luck.
You can try this!
Did you manage to get the front knob off? Usually just a small hex screw holding it on. That should get you access to the bearing assembly. In fact maybe the knob has just worked it's way too tight to the faceplate making it difficult to turn. The gap should be similar to the other knobs.
If that doesn't work you may have to remove all the knobs and the faceplate itself. That will get you in even closer to see what is going on.
I don't have that Preamp but looking at all the pics on the net appears to be pretty straightforward in disassembly.
You'll probably find nuts and washers both sides of the inner wall that can be loosened so you can remove the entire shafts assembly if necessary.
Be careful as bearings and or retainers may pop out. Don't want to lose any of the small pieces. Also pay close attention for reassembly. I usually take pictures to help me recall.
Hope this helps!
Cheers!
Jonesy
"I know just enough to get into trouble. But not enough to get out of it."
You can get something like this!
BCR,
Thanks, I appreciate the suggestion. I'm just too darn much of a purist. While I'm only trying to get inputs for CD and Theater I'd still like to find a way to use the M3a for best possible sound. Thanks anyway I do apprecaite it though.
For about 10 minutes I was excited. I saw that there are spare digital inputs on my EAD DSP 7000 converter that I use for my transport. There is one toslink and one coax. When I realized there are toslink and coax digital outputs on the TV I thought Wow Looks like a solution. I could use the D/A converters' input swtich to choose.
Unfortunately after I connected an RCA cable to the digital output/input even though the "Locked" LED lit, all I got was tick tick tick from the speakers. I guess TV's don't put out PCM digital like a CD player does.
I found the TV's service menu (FYI For LG 52 inch LCD TV: Press Menu on remote and TV at same time for 5 seconds. Code is 0000) but didn't find anything that would allow me to select the digital output format.
Well hopefully someone may have experience with the M3A. Thanks again.
John
Opus 33 1/3
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