Thats me that did the repair on the amp. It became perfect.
Schematic is provided here
https://www.conradjohnsonowners.com/vie ... f=17&t=128
Search found 14 matches
- Sat Jan 16, 2021 5:12 pm
- Forum: Amplifiers
- Topic: MF-2500a - Service Manual
- Replies: 5
- Views: 1181
- Wed Mar 14, 2018 3:07 pm
- Forum: Amplifiers
- Topic: MF2500 throwing 68 DCvolt out on right channel
- Replies: 21
- Views: 5954
Re: MF2500 throwing 68 DCvolt out on right channel
It plays extremely well. Had a ground loop problem with one of my preamps. That was fixed and now it is dead silent and absolutely no transformer humming also. According to my knowledge the only "soundwise" difference between a 2500 and a 2500A is the new discrete rectifier diodes. jahatl5...
- Mon Mar 12, 2018 2:29 pm
- Forum: Amplifiers
- Topic: MF2500 throwing 68 DCvolt out on right channel
- Replies: 21
- Views: 5954
Re: MF2500 throwing 68 DCvolt out on right channel
Yes - unplugged for about a year
Now it sings..
Schematic coming soon to an email near you..
Now it sings..
Schematic coming soon to an email near you..
- Mon Mar 12, 2018 5:20 am
- Forum: Amplifiers
- Topic: MF2500 throwing 68 DCvolt out on right channel
- Replies: 21
- Views: 5954
Re: MF2500 throwing 68 DCvolt out on right channel
Thanks alot for your reply :) Started up my "fixed" MF2500 yesterday. No smoke, no hum in transformer. Adjusted dc offset and bias. Looks stable and fine. Will do some more testing perhaps today. Also have done some small modifications. And as far as I understand - it seems as the biggest ...
- Thu Mar 08, 2018 2:58 pm
- Forum: Amplifiers
- Topic: MF2500 throwing 68 DCvolt out on right channel
- Replies: 21
- Views: 5954
Re: MF2500 throwing 68 DCvolt out on right channel
Thanks alot for a good answer.
Did they respond on why it threw 68Vdc on right channel?
Did they respond on why it threw 68Vdc on right channel?
- Sun Mar 04, 2018 4:11 pm
- Forum: Amplifiers
- Topic: MF2500 throwing 68 DCvolt out on right channel
- Replies: 21
- Views: 5954
Re: MF2500 throwing 68 DCvolt out on right channel
Did CJ say what was wrong with the amp? What was fixed?
- Fri Feb 23, 2018 4:22 am
- Forum: Amplifiers
- Topic: MF2500- Thoughts on those who've had it; what to expect good and bad
- Replies: 2
- Views: 1421
Re: MF2500- Thoughts on those who've had it; what to expect good and bad
Have one. Been on "service" at my home for 1 year. It is finished. Havent powered it up yet
- Wed Jan 03, 2018 4:53 am
- Forum: Amplifiers
- Topic: MF2500 throwing 68 DCvolt out on right channel
- Replies: 21
- Views: 5954
Re: MF2500 throwing 68 DCvolt out on right channel
Have one that did excactly the same. Many parts are fried including one pair of output transistors. Look here http://www.conradjohnsonowners.com/viewtopic.php?f=17&t=1118 and here http://www.diyaudio.com/forums/solid-state/306733-conrad-johnsen-mf2500.html CJ was kind enough providing schematics.
- Mon May 01, 2017 3:08 am
- Forum: Troubleshooting/problems/manuals/schematics
- Topic: CJ MF2500 fault - smoke
- Replies: 6
- Views: 2512
Re: CJ MF2500 fault - smoke
Q13 (small signal) mje340 on the left channel was also gone. CJ has stopped responding. Anyone know where to get a service manual? After it is finished I will chech bias dc offset and so on. Also did a recap of the psu and changed one fuseholder there. http://www.hifisentralen.no/forumet/attachments...
- Fri Apr 28, 2017 5:07 am
- Forum: Troubleshooting/problems/manuals/schematics
- Topic: Official Schematics and Manuals Thread (Registered Users)
- Replies: 172
- Views: 130629
Re: Official Schematics and Manuals Thread (Registered Users)
Does service manual for the MF2500 exist?
- Sat Apr 22, 2017 7:55 am
- Forum: Troubleshooting/problems/manuals/schematics
- Topic: CJ MF2500 fault - smoke
- Replies: 6
- Views: 2512
Re: CJ MF2500 fault - smoke
Only one pair of output transistors were gone.
1 2sc3282 and 1 2sa1302..
Anyone know where to get a couple of genuine Toshibas?
1 2sc3282 and 1 2sa1302..
Anyone know where to get a couple of genuine Toshibas?
- Fri Apr 21, 2017 6:25 am
- Forum: Troubleshooting/problems/manuals/schematics
- Topic: CJ MF2500 fault - smoke
- Replies: 6
- Views: 2512
Re: CJ MF2500 fault - smoke
A loose fuse holder (only soldered at one end to pcb) Q12 (mpsu60l), Q23(nsdu57) and R12 (100r) minimun are broken on left channel. Waiting for some equipment so I can du some more digging..
Probably more that is broken.
Probably more that is broken.
- Wed Apr 19, 2017 5:26 pm
- Forum: Troubleshooting/problems/manuals/schematics
- Topic: CJ MF2500 fault - smoke
- Replies: 6
- Views: 2512
CJ MF2500 fault - smoke
Hi, have had this for a while but have never tried it Anyway - replaced all fuses (3 were blown) just to test. On fuse on the back and 2 on the pcb. Connected a DMM on each loudspeaker terminal and fired up. Left channel showd 72Vdc - Right channel ~100mV. After some seconds a bit of smoke appeared ...
- Tue Apr 18, 2017 5:08 pm
- Forum: Member Presentation Thread
- Topic: New member from Norway
- Replies: 1
- Views: 1183
New member from Norway
Hi there. Have alot of equipment including a MF2500.
It has some issues which I hope can be fixed.
It has some issues which I hope can be fixed.