McIntosh MR-65 tuner needing vacuum tubes

[jejovan]

Hello,

I just picked up a McIntosh MR-65 tuner that is missing a couple of vacuum tubes. Since I am a nube when it comes to tube equipment, I have the following questions:

1) How critical is it that the tubes match one-another?

Right now, it looks like most, if not all tubes installed in the tuner are GE made specifically for McIntosh.

2) How do you know where each tube goes when a number of them appear to be the same size?

I found a vacuum tube listing the following tubes used: 2-6BN4A, 12AT7, 4-6AU6, 6CS6, 6BN8, 6U8, 6C4, EZ80/6V4 but have no idea where each should be installed.

3) When I power the tuner on, most if not all of the existing tubes glow. Should I still replace them or as long as they are glowing, are they "working" correctly?

Any help would be much appreciated! Thank you!

 

[Steve Williams]

welcome to WBF jejovan

Isn't there a schematic on the top plate showing tube placement

 

[DaveyF]

As Steve said, plus I wouldn't be powering up the unit if tubes are missing from the circuit.

 

[jejovan]

You are correct - I guess I should have looked a little closer. Any idea on matching replacements or whether or not all should be replaced with new?

 

[Steve Williams]

I would retube

 

[RogerD]

This might help.

http://www.audiokarma.org/forums/showthread.php?t=72851&highlight=mr65

http://www.audiokarma.org/forums/showthread.php?t=87157&highlight=mr65