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McIntosh - Hints and Kinks

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Sticky/dirty PanLoc rods

Hi, folks.

I have a question for the gurus here: how do I disassemble an MC2105 to clean and lube the PanLoc rods that go through the chassis? :scratch2:

One can be pushed in, but feels dirty/sticky, the other does not move when I tried to depress it. I didn't try as hard as I could, since I hate making things worse. :D
 
Pull the bottom off and look for the 2 bars that run down both sides. There are entry/exit points front and back. Inspect the binding one for straightness as the source of binding. Next, inspect the back ends of the Panloc rods to ensure that the tangs are not bent which would cause binding as they mate to the Panloc shelf rails. Lastly, check that the receivers on the shelf rails are not binding. They should float in order to mate properly with the tangs on the rods in the chassis. No lubes were used, IIRC, during production.

Cheers,

David
 
Thanks very much, I just wasn't persuasive enough when lifting the bottom off. :thmbsp:

No bends, dirt, corrosion or anything else wrong with the rods. :banana:

Some HACK put the wrong screws in the bottom next to where the rods go through the springs (screws are too long) and they were pushing the springs over and preventing the rods from moving.

A man's got to know his limitations, and somebody found his working on this amp. :screwy:

I'm glad I bought the shipping carton for this from McIntosh ($70 shipped), it's going to Terry for a thorough once-over, once his backlog is down to a dull roar. Hopefully he doesn't find any other surprises while he has it.

I guess I should subscribe now that I got a helpful tip! :yes:

<edit> Success! Picture of the amp in its new box, and a picture of the Forte IIs it's driving:
 

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I had a channel going dead while I was swapping my test case MCD7000 in and out of the test system. I caused the outer RCA connectin to spin which pulled the center connection causing it to contact the ground killing the channel.

Beware of tight RCA plugs.

Glad I still have my tried and true old Weller from slot car chassis making days in the 60s
 

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MC300 and 'turn-on delay' feature

From reading the owner manual of my MC300, it mentioned that the amp has a 'turn-on delay' of 2 seconds when the unit is turned-on, to avoid pop and thump. However, my speakers (connected to the MC300) always make a slight soft 'pop/click' sound immediately when the MC300 is turned on. Is this normal or does this mean that the 'turn-on delay' circuit is bad? Any advice is really appreciated.
 
Then on all but the MC300, make sure volume is at normal listening level, then turn on the 300, does it have a delay then the output comes on or does it play instantly?
If it has a delay then the circuits are working and you are possibly picking up a pulse in your speaker wires, possibly repositioning them from the AC lines may help.
 
dewickt said:
Then on all but the MC300, make sure volume is at normal listening level, then turn on the 300, does it have a delay then the output comes on or does it play instantly?
If it has a delay then the circuits are working and you are possibly picking up a pulse in your speaker wires, possibly repositioning them from the AC lines may help.
Click to expand...

Thanks Terry, I will try it when I get home tonight.
 
dewickt said:
Then on all but the MC300, make sure volume is at normal listening level, then turn on the 300, does it have a delay then the output comes on or does it play instantly?
If it has a delay then the circuits are working and you are possibly picking up a pulse in your speaker wires, possibly repositioning them from the AC lines may help.
Click to expand...

Terry, I'm afraid that the delay circuit in my MC300 is bad. I did the experiment as you recommended and as soon as I turned on the MC300, the music played immediately. The manual says there should be a 2 second delay but my MC300 obviously did not delay at all. Do you have a rough idea how should I attack this problem? I currently don't have the service manual for this amp. Thanks for the advice.
 
Wish I could help more but I do not have the service literature on the MC300, have not had one on the bench so I have not ordered one, will do it today...
 
dewickt said:
Wish I could help more but I do not have the service literature on the MC300, have not had one on the bench so I have not ordered one, will do it today...
Click to expand...

Oh Terry, don't order one just to answer my question. Let me order one and send you a copy.
 
Terry, I sent you a copy of the MC300 SM a few days ago, if you did not see it, check your 'spam email folder'.
 
See page 15 the meter board, Q3 and Q4 are the turn on delay, network on base of Q3 sets the time with Q4 the switch.
 
Ok, this is killing me:

Bought an MR75, tested it before I left. Tuner a little noisy, but other than that (and the wood case & Panloc mounts that don't seem to be for this unit), everything was working fine when I left. :yes:

Set it in it's place at home, make all the connections and power it up, pulls in stations and sounds good except for one detail:

In mono mode, both channels work.
In stereo mode, only the right channel works.
This is true for both variable and fixed outputs. :no:

What the heck did I do to this thing? :scratch2: It sat on the passenger side front seat floor of my car for the whole trip, cushioned by the carpet and some thick carpet floor mats. No sliding around (The car or the tuner, I took it easy instead of my usual commute mode :D), no real bad bumps although the suspension in the car is a little on the firmer side.

Any common failures on this model? Search didn't help... I'm looking for the manual/schematic as we speak.
<edit> No schematic or service manual to be found, only owner's manual. :-(
 
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MR75 uses a plug in module for thr IF and MPX functions, the connector can get dirty with age causing intermittent operation. Pull the 4 screws holding it in place, pull out of socket and flush the board edge and connector with DeOxit D5, plug in and out several times to self wipe the connector. This should solve the problem for many years to come.....
 
Thanks, Terry, I'll get it on the bench tonight (hopefully) and break out the DeOxit. I thought I was going crazy for a couple of hours there...

Man, what a resource this forum and it's members are. My subscription was the best money I've ever spent on my audio gear, I hope this post gives non-subscribers the push they need to start supporting AK!

<Update>

No love. :sigh:
Still a one-legged man in an ***-kicking contest. :no:

I took the time to clean up the front and tuner glass, it was a little funky. I'd try to diagnose it, but I can't find a service manual for it. There's a local (within 50 miles) shop that says they can fix it, I might have to resort to that but finding a repair source on Google is kind of sketchy.

Terry, I'd ship it to you but your backlog is still over a month and a half out, and it looks like you're having issues storing boxes.

Why do you have to be so popular? :scratch2: :D
 
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