ON transistors

marcok

Chief Journeyman
Joined
Jun 9, 2014
Messages
636
Location
Milan Italy
Tagline
I'm very curious about any tech item
#1
Are these components good ?
I need a pair or two of MJ 15015 and MJ 15016 for my Carver M400A . ( It's in protection mode )
Probably the original ones are good , but at present I'm not sure .
Anyway , if I have understood well , this could be the new brand name of Motorola .
The location is Phoenix and they are made in Mexico .
Thank you in advance and ciao .
Marco
 

WOPL Sniffer

Veteran and General Yakker
Joined
Aug 10, 2015
Messages
4,433
Location
Arizona
Tagline
Screw it
#2
ON Semiconductor was founded in 1999. The company was originally a spinoff of Motorola's Semiconductor Components Group. It continues to manufacture Motorola's discrete, standard analog, and standard logic devices.

ON Semi is a great company ant they make GREAT products. As long as you stay away from China sellers, you should be good.

MJ15022/15023 may be a better choice for the voltage and current specs in the 400
 

marcok

Chief Journeyman
Joined
Jun 9, 2014
Messages
636
Location
Milan Italy
Tagline
I'm very curious about any tech item
#4
Thank you , Perry !
Now I have to dissambly my M400A .
It's a "complicated "procedure .
I have to test the caps ( six ) , the bridge rectifier ( four ) , four 0.1 Ohm resistors ( 1 it's open ) ,
the triac ,the opto coupler and the power transistors ( 12 ) .
Consider that this amp is bridge amp ( like car amp ) with 3 supply voltages . ( 25, 50 , 75 V )
After 37 years everything is possible .
I could assume that is a class GH amp .
Ciao
Marco
 

WOPL Sniffer

Veteran and General Yakker
Joined
Aug 10, 2015
Messages
4,433
Location
Arizona
Tagline
Screw it
#5
Marco, I have a guy sending me 2 M400A amps for restoration. If it's an active component (transistors, triac's, Rectifiers, caps etc), it's getting replaced while i have them open. The precision resistors will be scrutinized very closely and replace if drifted. As for Carvers Magnetic Field Amplifiers using the triac and shit, you can have them. They can be a pain in the ass to get/keep running and the small form factors suck to work on since they are packed like a sardine can so troubleshooting them requires total disassembly. I contemplated getting a pair of them and quickly changed my mind when I surfed the net and discovered the magnificent world of WOPL. I decided they would make an excellent paperweight though since they look so cute. The guys who did the reviews liked them because they were a good amp for the price. Notice they said GOOD and not great. I didn't want a good amp. I wanted a great amp. Have fun with the restoration, I look forward to building a pair of them but they will be going back to the owner when mine are done. I still may try to talk some sense into him and look for a great amp.
 
Last edited:

WOPL Sniffer

Veteran and General Yakker
Joined
Aug 10, 2015
Messages
4,433
Location
Arizona
Tagline
Screw it
#6
Oh, there are a few obsolete components in these amps. Check it out before you sink a bunch of money into them.
 

marcok

Chief Journeyman
Joined
Jun 9, 2014
Messages
636
Location
Milan Italy
Tagline
I'm very curious about any tech item
#7
Don't worry ,Perry !
My hifi guru ( a close friend since I was teen ) was a super service engeneer .
He had official repair center for PL , Carver , Mark Levinson and so on .( now He's retired but for friends .....)
They phoned me 5 minutes ago and he told he has some MJ15022 and MJ15023 .
Obviously he has a variac .
What are the obsolete components ?
Ciao
Marco
 

WOPL Sniffer

Veteran and General Yakker
Joined
Aug 10, 2015
Messages
4,433
Location
Arizona
Tagline
Screw it
#8
What's a Variac have to do with it? As for obsolete parts, you didn't look at the parts list???
 

marcok

Chief Journeyman
Joined
Jun 9, 2014
Messages
636
Location
Milan Italy
Tagline
I'm very curious about any tech item
#10
My hifi guru approx . 40 years ago .
He helped me in restoring 2 PL 4000 and a PL 700B .
Generally I search the spares , study all the details and test all critical points under his suggesttion and after he fixes the issues .
At present we are discussing about the probable issues by phone and e- mail .
Already bought 2 drivers ( MJE 15030G ) and 4 x 0.1 Ohm resistors .
Consider that I was a desisn engeneer before and after a system engeneer .
Repairing devices needs another approach and to be honest I''m not confident with hi power devices.
Ciao
Marco
 

Attachments

WOPL Sniffer

Veteran and General Yakker
Joined
Aug 10, 2015
Messages
4,433
Location
Arizona
Tagline
Screw it
#11
Marco..... Most Engineers know how to spell Engineer

"Consider that I was a desisn engeneer before and after a system engeneer ."

HUH?????


Is that a picture of Spock working on a 700B??
 

marcok

Chief Journeyman
Joined
Jun 9, 2014
Messages
636
Location
Milan Italy
Tagline
I'm very curious about any tech item
#12
You are right ,Perry ! I made a mistake with engineer !
Ciao
Marco
PS : It's a PL 400
 

Gepetto

Administrator
Staff member
Joined
May 15, 2011
Messages
7,669
Location
Sterling, MA
Tagline
Old 'Arn Enthusiast
#13
My hifi guru approx . 40 years ago .
He helped me in restoring 2 PL 4000 and a PL 700B .
Generally I search the spares , study all the details and test all critical points under his suggesttion and after he fixes the issues .
At present we are discussing about the probable issues by phone and e- mail .
Already bought 2 drivers ( MJE 15030G ) and 4 x 0.1 Ohm resistors .
Consider that I was a desisn engeneer before and after a system engeneer .
Repairing devices needs another approach and to be honest I''m not confident with hi power devices.
Ciao
Marco
Digging the strip chart recorder in the background...
 

marcok

Chief Journeyman
Joined
Jun 9, 2014
Messages
636
Location
Milan Italy
Tagline
I'm very curious about any tech item
#14
Joe.,
I will ask him for details .
You can see a Tek scope and Radford signal generator .
Ciao
Marco
 

marcok

Chief Journeyman
Joined
Jun 9, 2014
Messages
636
Location
Milan Italy
Tagline
I'm very curious about any tech item
#15
B&K printer and B&K oscillator to check RIAA linearity on Radford and AGI preamps .
Ciao
Marco
 

marcok

Chief Journeyman
Joined
Jun 9, 2014
Messages
636
Location
Milan Italy
Tagline
I'm very curious about any tech item
#16
My Carver M 400A is O.K. now . My hifi guru made a miracle in 2 hours only .
Fault : a PNP transistor shorted .
Replaced both PNP and NPN with genuine spares from Mark Levinson or Cello .
Cause : a momentary short at the output in power down mode , but with charged caps . I'm the guilty .
Bias : O . K . ( approx 450 mV ) and no DC ).
Test equipment : Variac and a little speaker ( Ar 8bX ) with a 100 uF cap in series .
I was cleaning the banana plugs ok my AR 9 , because there was a channel lower than the other .
After I discovered that reason was the oxidation of switches of AR 9 .
Another victim of the heat ( 40° C RH 65 % ) This summer was a disaster in Italy .
Thank you Perry for your suggestions .
Ciao
Marco
 

WOPL Sniffer

Veteran and General Yakker
Joined
Aug 10, 2015
Messages
4,433
Location
Arizona
Tagline
Screw it
#17
a miracle? Hardly

Cause : a momentary short at the output in power down mode , but with charged caps . I'm the guilty .

That make no sense unless you were monkeying with it while it was powered up????? Tell us what you really did. Pulling speaker wires while it was powered up???
 

WOPL Sniffer

Veteran and General Yakker
Joined
Aug 10, 2015
Messages
4,433
Location
Arizona
Tagline
Screw it
#18
The caps bleed off rather quickly....

During Monsoon's here in Az, My garage regularly sees 45 C (113 F) and humidity levels of 60% or higher and the Klipsch/Yamaha/epicure stuff runs like a top. I know it went through worse weather swings in my garage in Minnesota. Winters -20 F with 0% humidity to summers which went to 80% humidity and 100 F..... Italy has it easy compared to what our shit goes through over here.
 
Last edited:
Top