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Strange Mac 1700

M

msbuescher

New Member
I have a Mac 1700, serial number 31J30 that I am in the process of cleaning up and doing a basic tube replacement. My question is, where are the (2)
6DS4 tubes as listed in my original schematic? Was there a design change somewhere at some time.
I have found:

3- 6AU6
1- 6CS6
1- 6EA8
1- 12AU7

Please help get this old friend going again......
 
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That's a nuvistor tube. Very small metal enveloped tubes about a half an inch long. Maybe that will help
 
heres the picture i forgot to attach in the other post before it got closed.
 

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Thank You.
What is the best internet site to purchase tubes?
Any suggestions as to modifications (different vacuum tube replacement) or stick to the original config?

Thanks in advance.
 
A couple of other thoughts here:

- If you're planning to replace the FM tuner tubes, then be prepared for an alignment. You'll need it. Otherwise, leave the old tubes in it as they rarely need much in the way of replacement. I do hope you've numbered the old tubes as to where they were removed from. This is particurlarly important in the IF strip.

- Substituting different tube numbers for FM tuner tubes takes a bit more knowledge than in audio circuits mainly because they are used for other functions like oscillators and filters and not just amplification of a signal.

- Lastly, the power supply likely needs to be rebuilt in order to generate the right high voltage and have solid regualtion. Only then would I attempt to swap tubes in a tuner and even then following with an alignment.

As for tube suppliers, I've used Jim McShane as a supplier for many as well as NOS Tubes, who posts here. I'm sure there are others but I stick to ones I know.

Hope that helps.

Cheers,

David
 
Hi, I also have the MAC1700, will be sending it to Mark Wilson of Absoundlabs.com to have a drop out and static that appears in left channel, I guess caps are starting to go, so you may want to look at that also. But before it goes off for service I am cutting a new cabinet for it to be done in a burl veneer, but have not selected which one yet.
 
Geez I know this thread is getting old, but I have a set of schematics for the 1700 that had margin notes written by what appears to have been a Mac tech. If I recall there were some notes referred to changes and certain versions of the chassis had this or didn't have that...
Also I learned that there are cerain tubes that are acceptable substitutes for the originals.
 
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