I have had several ua739pc (plastic case) ic's fail in crown dc300a amps,
The ceramic case option was common in the earlier dc300a amps,
There is a fair amount of heat around the top of the dc300a main board, the only thing i have had to do re the ic power supply was to replace the tired zener and resistor associated with the ic supply....
I have no idea about the marantz problems, so i just cant comment. the dc300a runs 10volts into the ic , so i dont think its a huge voltage by any means.
The ceramic option seemed the way to go, i have 25+ year old dc300a's still running virtually untouched.
Some of the earlier r's and c's were bullit proof....
shame we cant say the same for some of the newer gear!
The ceramic case option was common in the earlier dc300a amps,
There is a fair amount of heat around the top of the dc300a main board, the only thing i have had to do re the ic power supply was to replace the tired zener and resistor associated with the ic supply....
I have no idea about the marantz problems, so i just cant comment. the dc300a runs 10volts into the ic , so i dont think its a huge voltage by any means.
The ceramic option seemed the way to go, i have 25+ year old dc300a's still running virtually untouched.
Some of the earlier r's and c's were bullit proof....
shame we cant say the same for some of the newer gear!
hi chris,
17volt sounds a little high, the ic in the crown's seems to go quite frequently, and some of the pre driver transistors are a little iffy!
i think a lot of the problems were down to component availability at the time, there appears to be no logic in transistor choice.
it amazes and amuses me the parts people use as "equivalents" at times, the range of available components seems to lessen every year .......
cheers chris
17volt sounds a little high, the ic in the crown's seems to go quite frequently, and some of the pre driver transistors are a little iffy!
i think a lot of the problems were down to component availability at the time, there appears to be no logic in transistor choice.
it amazes and amuses me the parts people use as "equivalents" at times, the range of available components seems to lessen every year .......
cheers chris
Hi krmaudio,
-Chris
I've always thought that. All in the name of headroom.
There is if you look at a catalog of that time period. I think they did amazing things back then with what was available to them.
Well, yes. Me too. Then again, you have to clean up after these amusing folk. So much needless destruction. Getting good parts for old gear is getting more difficult year by year.
-Chris
Need 2 FairChild UA739
Any body still have some spare UA 739 IC, I need 2. Please email me at edgarealty@hotmail.com, many thanks
Any body still have some spare UA 739 IC, I need 2. Please email me at edgarealty@hotmail.com, many thanks
UA739
Take a look at
http://www.alldatasheet.com/datasheet-pdf/pdf/113482/FAIRCHILD/UA739.html
Maybe I can get the UA´s here in Mexico, let me know if needed.
Regards
Take a look at
http://www.alldatasheet.com/datasheet-pdf/pdf/113482/FAIRCHILD/UA739.html
Maybe I can get the UA´s here in Mexico, let me know if needed.
Regards
UA739/749
The replacement part in metal can from NTE, 949 www.nteinc.com
See the att.
Best regards, R Amandi
The replacement part in metal can from NTE, 949 www.nteinc.com
See the att.
Best regards, R Amandi
Attachments
Ua739
Please let me know if you can help with the Ua, if not I will try from Mexico Cy.
Best regards
Ramon Amandi
Please let me know if you can help with the Ua, if not I will try from Mexico Cy.
Best regards
Ramon Amandi