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MC5100 Amplifier service guide

Traverso

Traverso

Active Member
Hello,

I have here a superb MC5100.
It is an all transistors integrated amp and was built by 1966.

I like to service it as the sound is somehow not that nice .
There is probably a service guide for this masterpiece.

Where may I get this service guide?

Thanks a lot for the feedback


Alain
 
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Further on is there a list of equivalent to the references indicated by MC.
One can find for example: Q1 Silicon NPN Transistor 132-503, transistor equivalence ?

Alain
 
Hello Alain

A service guide for Mc Intosh units do not exist . This is your experience who help you to diagnosis the reason of the trouble .
Why are you suspecting all the transistors ?
In the MA5100 all transistors used in preamplifier are noise selected and knowing a substitute or equivalent will bring you nothing . If you know what commercial type this transistor is , you have to buy 1000 pieces to make a serious sort to get may be 25 acceptable .
But the problem is what are the test method of the factory ?
How can you adapt your sort with no references ?
Lokking for equivalent is a dead end . Take the service manual (the right one with correct serial numbers involved )
You better check voltages and why the sound is not "good enough " in your point of view but not looking for sub .
 
Hello

Thanks a lot for the feedback and comments

I do not know this MA5100 and this is the very first time I am involved in it so i like to have the maximum available info before starting investigating
No service book available better than the one I found on HFE so I will find my way with a step by step and systematic approach starting with the PS

What has been noticed so far whatever the input, is a weaker signal on the right channel, audible distortion on both channels
Some noise is added when using the volume control
Also some commands react strangely for example when activating the phase command, it changes the sound on head phones and not on the loud speakers

Did you ever work with this MA5100? If so what did you notice important for the unit and may be for the one I have here

Thanks a lot


Alain
 
Also some commands react strangely for example when activating the phase command, it changes the sound on head phones and not on the loud speakers
impossible
for the simple reason that sound coming to headphone is coming from the same amplifier section . You can't get working well on headphone and no effect on your speakers except if one speaker (tweeter ? ) is dead !
Did you ever work with this MA5100 ? work with or work on ?
I have refixed more then 21 pieces in 42 years .
 
No speaker dead, actually after testing entirely the PS and Lytics on every PCB everything looked ok, I started one more time to clean up all pots, switches, input connectors one by one but using a Deoxit lke product without deposit
I let it dry for a night and started the next morning the testing and everything was back to normal and working nicely

happy about it

the MA5100 sounds very nicely

Thks a lot for your support

MA5100.jpg
Alain
 
The MA5100 was built in the 70's as you all know. Since it was built there have been VAST improvements in semiconductor design and manufacture. That said; it is not unreasonable for someone to query about a substitute that will work well in the MA5100 without hand picking through 1000 devices.
 
I'm glad you got it going.
I always try to clean all controls, switches, jacks, before I evaluate (if reasonably possible).
Even if I'm planning to do a restore.
I used to be surprised by the night and difference doing a good cleaning can make..
 
Yes happy as well and it is sounding very nicely
I could acquire a MR 77 tuner modified it to European 240V AC, easy task, and after realignment the fit with the MA 5100 is perfect
The Ma 5100 is driving now Celestion Ditton 66 without any effortMA5100 MR77on.jpg
 
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