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-   -   Preamp MC Intosh MA-6100 (DIY) (http://www.diyaudio.com/forums/solid-state/227952-preamp-mc-intosh-ma-6100-diy.html)

academia50 16th January 2013 03:21 PM

Preamp MC Intosh MA-6100 (DIY)
 
Hello friends this prestigious forum.
My English is very basic, and helped me with the translator on-line, are able to forgive.
I come to you for help to complete a DIY project I started many years ago and was postponed. It is McIntosh preamplifier section MA-6100.
The problem that is presented to me is that while I have the original circuit, do not know the exact nomenclature of the transistors of the same figure as only factory part numbers.
In some cases I have chosen replacements but may not be the best, and others have not been able to determine them (those carrying 75 Volts collector)
I have some photos, would be a great pleasure for me to complete the project, thanks for any suggestions and input!

Description circuit /Reemplacement / Parts Number/ Transistor Type
Q-101-102/ HR-71 or BC-416 /132-096 /PNP
Q-103-104/ BC-416 / 132-096 /PNP
Q-105-106 / ?? /132-095 /NPN
Q-107-108-109-110 / BC-239 /132-093 / NPN
Q-111-112 / BC-239 / 132-093 / NPN
Q-113-114 / BC-547-B ? / 132-095 / NPN
Q-115-116 / ?? / 132-095 / NPN
Q-303 / ?? / 132-078 / NPN

http://img705.imageshack.us/img705/1534/premac3.jpg
Uploaded with ImageShack.us

http://img204.imageshack.us/img204/3913/premac7.jpg
Uploaded with ImageShack.us

http://img826.imageshack.us/img826/7386/premac8.jpg
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Very thanks !

Regards

academia50 16th January 2013 06:13 PM

Attached preamplifier circuit !



http://img526.imageshack.us/img526/9...0servicema.jpg
Uploaded with ImageShack.us

academia50 17th January 2013 01:29 AM

Sorry, not be viewed correctly uploaded the circuit, I leave the links are all models vintage Mc Intosh!



Mcintosh Diagrams, Schematics and Service Manuals for FREE




http://www.schematicsunlimited.com/d...ice-manual.zip

academia50 19th January 2013 03:55 PM

Please anybody can help me? There must be people with expertise on Mc Intosh here.
It is very important for me, if I do not have the name of the original transistors, I can not find replacements, and by inference of the function and location of each transistor in the circuit is a big risk, the result can be very bad ...

Thanks again and as they sang The Beatles, Help for me! ;)

Kindhornman 19th January 2013 04:27 PM

Here is a link to another site that may have your answers. I also have an original MA6100 that is in need of repairs and if I find anything else I will try and post it here for you. Look around on this site as I see many questions about this particular integrated amplifier here.

Steven

MA-6100 5A fuses burnt (2 of 4) [Archive] - AudioKarma.org Home Audio Stereo Discussion Forums

TANDBERGEREN 19th January 2013 06:19 PM

You may have to read each transistor and put the list out here.
The only reference I find in the schematics seems to be Macintosh own partnumber and nothing else.
I'll be happy to help You and it may be possible I can provide You with some transistors even.

academia50 20th January 2013 07:00 PM

Quote:

Originally Posted by Kindhornman (Post 3333136)
Here is a link to another site that may have your answers. I also have an original MA6100 that is in need of repairs and if I find anything else I will try and post it here for you. Look around on this site as I see many questions about this particular integrated amplifier here.

Steven

MA-6100 5A fuses burnt (2 of 4) [Archive] - AudioKarma.org Home Audio Stereo Discussion Forums


Hello Steven

I had a look and is a specific remedy, unfortunately, no information on the stage transistor preamplifier. Anyway all useful.

Very thanks!

Rolando

academia50 20th January 2013 07:13 PM

Quote:

Originally Posted by TANDBERGEREN (Post 3333284)
You may have to read each transistor and put the list out here.
The only reference I find in the schematics seems to be Macintosh own partnumber and nothing else.
I'll be happy to help You and it may be possible I can provide You with some transistors even.

The problem is that I have to read transistors ....
Thanks for offering equal friend.
I keep looking

m2003br 25th January 2013 01:13 AM

Dear Rolando, your problem is very simple to be solved.
The transistors Q101-103 are BC416C, wich may be substituted by BC560C.
Transistors Q107, 109, 111 are BC239C, modern equivalents are BC550C
For Q105, 113 and 115, originals are GE X32W6047 ???!!! any NPN 100V, 300mW
are good, for example, 2N5550, 2N5551 as best choices, BC639, BD139, maybe MPSA42, BF469, BF869 as secondary choices.
If this preamp are to be used as independent preamp, don't forget to put a 220 ~ 470 ohms resistor in series with the output, and at least a 4,7uF in the position of C137.
Hope it help.

Cordiales saludos from Brazil,

Marcos

Kindhornman 25th January 2013 02:01 AM

Marcos,
thank you for that information, I am sure it will come in handy.


Academia50,
Where did you find the pots and switches that you have showing in your first post. I know that a few of the switches are no longer available from McIntosh and was wondering how I was going to replace them.

Steven


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