McIntosh 1900 Recap and Restore
- Thread starter CohibaJoe
- Start date
kevzep
Its all about the Music
You are doing a nice thorough job there, very tidy, nicely selected components....
I was just thinking with all the trouble you are going to whether you were considering replacing any of the transistors....?
They could also greatly enhance the audio quality by being replaced....
Thanks...Was thinking the same. Let me put a List together.
Terry...Do you have any tips on what Transistors to replace?
Going thru this...This could have been a Kit.
Modern replacement tranistors are often quieter than the originals....
If I measure frequency deviations when testing, a common solution is to rebuild the volume control. The center ring conducter can corrode like you would not believe. Also it is important that the outboard resistors and solder connections that apply the audio taper to the linear pot are correct.
Chassis ground rivet for speaker - (under PS board) is also a common issue.
If I measure frequency deviations when testing, a common solution is to rebuild the volume control. The center ring conducter can corrode like you would not believe. Also it is important that the outboard resistors and solder connections that apply the audio taper to the linear pot are correct.
Chassis ground rivet for speaker - (under PS board) is also a common issue.
I will tell you one thing...WOW...The music has opened up and that "Smearing" is gone. I can now here the instruments as each one Pop’s from the speakers.
No...I am not hearing things. I am almost running the Treble/Bass Flat as before Treble (3/4 R) and Bass (1/4 R). Also, the radio station I am listing to has LESS background noise.
Bump...
I am also going to replace the Output Transistors.
I am going to PM Terry if he can provide a Transistor List. I cannot find one
out there.
On hold till then...My parts are in for the Spec-1 anyway...cannot let the Solder Iron go Cold...
I cannot find a Complete list of transistors. I also reached out and..maybe keeping this close to the chest.
Next time I goto the repair shop I will ask as this is a MAC repair shop.
OK...I seem to have a issue with 1 Pre-Amp Board.
After about 10mins there is some static from the speaker which comes and goes...:scratch2:
Not sure were to start....but I am going to replace the Caps 1st...only 4. Can I have a bum Resistor?
It's been a bit on this update.
I am in need of the Transistors for the PreAmp Board (044-410). One board is crackling (comes and goes) and with the use of Freeze Spray (Thanks Terry) is was able to located the bad transistor.
I would like to replace ALL the transistors on the 2 PA boards.
BC 239C, 095 234, BC 416C
So...Calling out anyone who has replacement part #
I am in need of the Transistors for the PreAmp Board (044-410). One board is crackling (comes and goes) and with the use of Freeze Spray (Thanks Terry) is was able to located the bad transistor.
I would like to replace ALL the transistors on the 2 PA boards.
BC 239C, 095 234, BC 416C
So...Calling out anyone who has replacement part #
Attachments
Last edited:
OK...Looking at some past posts...this is what I found from MisterFishey:
McIntosh Part Number, original transistor number, then valid replacements:
132-093 - BC239 - BC549
132-095 - BC414C - 2SC2240BL and KSC1845(F or E) *
132-096 - BC416C - 2SA970BL and KSA992(F or E) *
132-105 - BC239C - BC549C
* The pin assignments/bias for these transistors are different from the originals, as shown here:
http://audiokarma.org/forums/attachment.php?attachmentid=257836&stc=1&d=1298346762
Transistor Data by McIntosh Part Number:
http://www.audiokarma.org/forums/attachment.php?attachmentid=321316&stc=1&d=1325964581
Now what is printed on Part#132-093 on my 1900 is BC239C.
PreAmp Board Transistor Part List:
132-095/BC414C - Q317, Q313 , Q305: Mouser Part# 512-KSC1845PBU
132-096/BC416C - Q301, Q303: Mouser Part# 512-KSA992FBU
132-093/BC239C - Q307, Q309, Q311: Mouser Part# 512-BC549C
McIntosh Part Number, original transistor number, then valid replacements:
132-093 - BC239 - BC549
132-095 - BC414C - 2SC2240BL and KSC1845(F or E) *
132-096 - BC416C - 2SA970BL and KSA992(F or E) *
132-105 - BC239C - BC549C
* The pin assignments/bias for these transistors are different from the originals, as shown here:
http://audiokarma.org/forums/attachment.php?attachmentid=257836&stc=1&d=1298346762
Transistor Data by McIntosh Part Number:
http://www.audiokarma.org/forums/attachment.php?attachmentid=321316&stc=1&d=1325964581
Now what is printed on Part#132-093 on my 1900 is BC239C.
PreAmp Board Transistor Part List:
132-095/BC414C - Q317, Q313 , Q305: Mouser Part# 512-KSC1845PBU
132-096/BC416C - Q301, Q303: Mouser Part# 512-KSA992FBU
132-093/BC239C - Q307, Q309, Q311: Mouser Part# 512-BC549C
Gregory
Soundco Kid
Yep.. noticed that on the C26 transistors.
On one board, the transistors painted blue have pins opposite from the transistors on the other board painted green.
Attention to these details is a must!!
-Gregory
Here is the LF&MPX Board.
Looks like I missed 2 resistors in my order...Going to place today.
I got a Note from McIntosh service. They have the Transistors on the PreAmp board...Also have a Sub for the parts if I use Mouser. I will compare the findings with what they send.
About done with this...Still need to install some Wire-Wounds.
Looks like I missed 2 resistors in my order...Going to place today.
I got a Note from McIntosh service. They have the Transistors on the PreAmp board...Also have a Sub for the parts if I use Mouser. I will compare the findings with what they send.
About done with this...Still need to install some Wire-Wounds.
Attachments
Just got a note back from McIntosh Parts:
PreAmp Board:
1. Q305, Q317, Q313: 132-095 – Replaced By - #13225400
2. Q307, Q309, Q311: 132-093 – Replaced By - #13225400
3. Q301, Q303: 132-096 – Replaced By - #13225500
I had them re-check as there are different Transistors for 1 & 2. They said the part is replaced with the Same one...:scratch2:
Any comment out there?
PreAmp Board:
1. Q305, Q317, Q313: 132-095 – Replaced By - #13225400
2. Q307, Q309, Q311: 132-093 – Replaced By - #13225400
3. Q301, Q303: 132-096 – Replaced By - #13225500
I had them re-check as there are different Transistors for 1 & 2. They said the part is replaced with the Same one...:scratch2:
Any comment out there?
Parts ordered from Mouser. I am going with the replacements from "MisterFishey" thread.
After 2 days with the MAC 1900 I got back from Terry, this will be listed on CL (lLocal Sale Only). The 1900 I am working on is sonically cleaner and more detailed.
I put back the Luxman R-117
in rotation till I get the 1900 completed. The MAC 4100 is on it's way..next week.
After 2 days with the MAC 1900 I got back from Terry, this will be listed on CL (lLocal Sale Only). The 1900 I am working on is sonically cleaner and more detailed.
I put back the Luxman R-117
in rotation till I get the 1900 completed. The MAC 4100 is on it's way..next week.
