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And then...

I

IvoCRO

Active Member
Can you imagine my happiness and joy? Finally 'The Day' has come as I drove few hundred kilometers/miles accross two countries and personally picked C32. I am sharing with you first picture that I took the very first moment we come home:

first_one.JPG

The seller told me that all is original and that he bought it in USA some 20 years ago and it works perfect. After a few hours of resting and mind setteling I have carefully approach for close examination. I have removed top cover to see overall condition:

cover_off.JPG

First thing that I saw is that cable from listen/mode switch board to volume potentiometer is not original. Someone has changed it with 'better quality?' cable and solder it directly to the board.

Ribbon cables should be changed as some of them shows aging and splitting.

Visually, only two capacitors looks bad - 10uF/63V ROE capacitors has something on top:

capacitors.JPG

But, it is obvious that capacitors should be changed after all these years. If you look closer, you will notice that there is two 741 op amps instead originals ones. These two should definitelly be changed.

And this is it - so far all other things looks original and untouched.

Here it is working:

working.JPG

Did I mention how happy am I?

Now, here is what I plan to do and all suggestions are more then welcome:

- fix all ribbon cables
- change capacitors
- find better feet than current ones which are not original
- clean all switches and potentiometers
- try to fix bubbles on front glass if possible (I think that c_dk sad in one thread that he manages to fix bubbles so I will kindly ask for his advice too when I come to that part)
- resolder connectors and other bad solder joints

I will try to document and take a picture of each step of restoration and post it here.

I plan to use preamplifier untill I have all parts needed for restoration. Most probably I will order from Mouser.

I need help with replacement of ribbon cables. I have been looking at Mouser catalog and there is a lot of combination and I am not quite sure which would be the best. I found combination of Molex socket and molex ribbon cable or same thing from TE Connectivity.
There is also FCI / Amphenol but I can't figure out from their data sheet what is in package.....
Even combination with plain pins would be fine, but I can't find appropriate female connector.
Any help and information on ribbon cable replacement is more than welcome, and if you have Mouser number, that would be even better:)

Best regards,

Ivo
 
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Well, first off, enjoy using it for a bit of time before you make wholesale upgrades. Just keep in mind that you are even though you are listening to a late production unit, it is 35 years old and many internal parts are well past their expected life cycle by 15 years. Expect some glitches to come up.

A recap of the input and eq board should be job one. Get the correct schematic for your serial number(might be in the Akdatabase) and all the electrolytics should be listed. When the boards are out reflow the solder connections for the audio path as shown by the schematic.

You can stabilize the ribbon sheaths with masking tape.

Enjoy the unit, use the multitude of control functions, this preamp really set a new standard when it was first released in 1978.
 
That is exactly what I am planning to do! I have connected it and I was amazed..........it plays wonderful! How will it play when refresh is done.......

Right now I just want to sit and listen more and more - same feeling when I have tried MC2200 for first time few months ago.

Here is a picture among friends:

friends.jpg

Ivo
 
You have a definite winner on your hands. Enjoy the music and refurbishing it down the road.
 
Old radio is Philips 938A from year 1933. It is very nice radio in very good condition which I have found and saved from an old attic.
 
Very nice Evo, enjoy your c32 its a great pre amp the phono preamp is also very pleasing, what turn table will you use it with?
 
Thanks all. Turntable is Thorens TD150. Very simple and very good model.

I am looking at CohibaJoe's thread and there is one thing that is not clear to me. In #38 of this thread is sad that LM201N (Mc number 133-068) is replaced with LM741CN. However, I have two LM741 in place of IC601 and IC602 (Mc number 133-043). And I found in older threads that for 133-043 can be used LF356N.

Now, can anyone tell me is:

133-068 = LM201 = LM741
133-043 = ? (in my unit there is LM741 in socket) = LF356N

Thanks all,

Ivo
 
According to my late 80s McIntosh semiconductor data sheet:

133-068 is a LM201AN a bifet opamp
133-043 is a LF356 a opamp

Taking a quick look thru the mid 80s and late 80s data sheets I saw no LM741s recommended.

There is much written on the net about IC or opamp rolling. Certainly much research was done by National, Semantics, TI, Analog Devices, etc. to design "better" audio ICs than the bench mark 5532 and 5534s. Most of that "sound better" research has been supplanted by surface mount, low voltage, and consolidation research.

A typical 70s era preamp has many restoration needs before IC rolling makes sense and you must be careful with the modern higher slew rate devices to not create oscillation issues..

I personally have 2 MCD7000 cd players and a MQ104 with some of these hotrodded devices in them, so far with no issues. I would not dare to put them in a client's unit while the low noise 5532s and 5534s are still available.
 
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