Steven Tate
CEO Flat Forehead Soc.
I would be checking output transistor H002 and driver H756 as well as R772. Something is shorted somewhere. Did you replace the drivers? If so, with what? If the output wasn’t the cause, it could be a victim.
MARANTZ 2230 power amp. PLEASE.help.
jFF_Bulbo
Active Member
Hello. to finish this thread
I installed new On semi mj15024g´s fron Mouser. I instaled insulators on TO-3 pins.
i never found shorts on P750. After this the R772 and H752/751 never exploded/ruined again. The bias is now stable. DF offseet set to 30mv (gnd-j758).
135 (or more) new pieces, new leds, new vellum... it is nothing but a beautiful unit, the best unit i´ve done until this moment.
Thank you to all of you, specially sensei Catrafter.
I installed new On semi mj15024g´s fron Mouser. I instaled insulators on TO-3 pins.
i never found shorts on P750. After this the R772 and H752/751 never exploded/ruined again. The bias is now stable. DF offseet set to 30mv (gnd-j758).
135 (or more) new pieces, new leds, new vellum... it is nothing but a beautiful unit, the best unit i´ve done until this moment.
Thank you to all of you, specially sensei Catrafter.
Steven Tate
CEO Flat Forehead Soc.
Great looking result! So, does it seem the output transistors were the source of the problem?
jFF_Bulbo
Active Member
I couldn't identify the problem. Transistors removed are functional, un fact the precios generic 15024 souds Fine.... I just instalé the imported On semi un order to make the unit more atractive.
The problem stop when i intalled the insulators.
But i never found the reason for transistor ir resistor mal fuction.
Do you mean the little tubular insulators over the leads? If they were shorting before, a quick resistance reading to ground on the Base, Collector, and Emitter would have revealed it. I have seen those from the factory that way, probably be cause there was enough "play" (or misalignment) that the leads could short against the heat sink. Glad you got it going!
jFF_Bulbo
Active Member
Well...
I AM testing it and ir sound ... Low... Sound good ay ant level... But i need half turn the volume to feel the power...
I read (here, i Guess) after recap the unit needs to be playing a few hours (burn-in proces?) With low volume un order to Energize the nes puedes properly. This is whra i haven't done.
Do You run your recapped unit un this way???
Regards...
I AM testing it and ir sound ... Low... Sound good ay ant level... But i need half turn the volume to feel the power...
I read (here, i Guess) after recap the unit needs to be playing a few hours (burn-in proces?) With low volume un order to Energize the nes puedes properly. This is whra i haven't done.
Do You run your recapped unit un this way???
Regards...
The volume level doesn't change after a recap. My own 2230 doesn't get very "loud" until about 11 O'Clock on the volume control and that is "normal" for these in most cases. These are not "high power" receivers anyways.
Does your 2230 "sound" clear and alright at low volume? No distortion? Or does it sound very "weak"? When you turn it up to about 11 O'Clock in the volume, how is it then?
jFF_Bulbo
Active Member
Hello. A very good sound on AUX, PHONO and Tape. Radio sound a little weak.
Just a dirty sound in AUX (buzz) when cable is conected and no music playing, once the music is playing or the cable is diconected, the unit is quiet.
Ground problem?
My unit has a pair of ceramic caps conecting ground from AUX -rca to chasis, i can´t find them on service manual..... are this normal?
jFF_Bulbo
Active Member
yes sr, i tried it all, i never found the problem...... i just isntalled inslators on output transistors and the unit works fine..... as i said, the previous OEM transistors was removed but are functionals, the news ON semi has the mission of make the unit more atractive.Do you mean the little tubular insulators over the leads? If they were shorting before, a quick resistance reading to ground on the Base, Collector, and Emitter would have revealed it. I have seen those from the factory that way, probably be cause there was enough "play" (or misalignment) that the leads could short against the heat sink. Glad you got it going!
I guess o short with the heatsink... but i never could find it.
The unit is working properly, just a noise on aux input when a cable is conected with music playing.... maybe could it be aldo mi rca wire.....
I use an isolation transformer on my music player. Without it there will be a hum on many units because of a ground loop. The 2230 just happens to be one such unit. They are very inexpensive and well worth it. It's just a little "adapter" with male and female RCA cables that plugs inline with the AUX input. They go by many names such as "ground loop eliminator" and "Hum eliminator" to name a few.
Yes, that's normal for many units. Some have them, some don't.
jobimdream
Member
think it's worth a mention this same thing happened to me when working on a BJT. difference is my smoke scare came from my error, not a bad part. reason for hot glow and smoke was a Q-tip fiber left behind from cleaning up surfaces before soldering arced. had to actually use a scalpel to cut out the fiber melted in the board to get it to stop arcing. don't use Q-tips anymore now use eye shadow applicator swabs cause they're cheap.
@Steven Tate that's a great schematic, glad I found this, thank you.