good day to all ,I am spankin new here and this is my second post fortunately i think it is in the relevent area> I have a couple of questions regarding a recent purchase.. last week i bought a pair of altec 1590E amplifiers.......wait,dont be so quick to judge. its.just... that......their so big.......and heavy.and wonderfully constructed ......kinda like a sherman tank.but a little less noisy!.the guy said.one works and the other one has a couple of bad resistors is all.h mmmm has anyone ever heard that before.anyway after about 2 seconds of haggling i forked out the 62 dollars for the pair called a wrecker and dragged them to the lair!where i promptly ravished them and discovered the one that works .......doesnt! with a grand total of 6 blown motorola 5878 mex 5717 bjt transistors. and a few odd resistors blown.. the amps are real masterpieces of build quality and topology. and im sure i can do something with them.....just becouse i live in cancun please refrain from the obvious boat related comments!......these wont be used for anchors!!!!.my question is this is there a common modern substitute for these 5878 transistors....are their some transistors that would offer some improvement in power or sound quality.......or what is the recommended replacements.. thanks for all the wisdom!!! Brian
A brief look at a 5878 suggests a MJ15003 TO3 might substitute OK, the 5717 is a darlington type transistor so you need to do some research to substitute it. A schematic too would be handy.
There are reasons why transistors blow, so carefully check with power off one amp to the other, to
spot these reasons. Shorts, are high on the list.
Cheers / Chris
There are reasons why transistors blow, so carefully check with power off one amp to the other, to
spot these reasons. Shorts, are high on the list.
Cheers / Chris
thanks chris a couple of the transistors were shorted others open.i tore into the other amp and exactly the same failures 6 transistors bad and the same resistors as the other amp.these amps supposedly. were used in the BOOM here in cancun a real mecca in the late 80s up to about 2001 .i suppose they were badly connected shorted speaker wires who knows what evils theve seen .i checked for shorts and obvious problems and installed some toshiba 250 424 transistors and wired it for a 4.5 ohm load and hooked it up to see if it goes....................it goes !! as the test speaker has little or no sonic capabilities whatsoever i couldnt really evaluate its performance . so im researching the transistors to see if there is a good or better replacement! thanks for the quick reply and mighty hi ho to the pirate guy!
The 424's look like a solid replacement to me.
2sd424 http://pdf.dzsc.com/20090603/200904280540044817.pdf
2n5878 http://www.svntc.com/TPDF/297.pdf
2sd424 http://pdf.dzsc.com/20090603/200904280540044817.pdf
2n5878 http://www.svntc.com/TPDF/297.pdf
Last edited:
thanks jerluwoo so i shouldnt worry about the slight differences in values between the two different types .................i s overall sound quality changed by what type of output transistor you use.........and if i use the 424,s now what transistors would be the very best that i could use as far as power gain .sonic improvements.in the future would a mj150016 work.and would the 185 watt dissipation be heard at the speaker .ie more headroom, better dynamics, thanks for all the help...
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.