Tried new things on sysasim 5_3 amp

[space2000]

hi, here is the sysasim design and i made change on only power transistor with 2sc2922 and 2sa1216. i dont know is there need to change resistor too. need help. i had power the amp, it works nice but only the power transistor gets too hot. how can i use this transistor on this board?

thank you

[MJL21193]

Hi,
It could be oscillating. Do you have a scope?

[space2000]

thanks , i don't have anu osiloscop to check. is there any way i can use it?

thank you.

[MJL21193]

Did you build it exactly like the schematic? Did you include the output Zobel (R4 and C18)?

You might want to remove C14 and see if the (possible) oscillation stops.

[space2000]

yes, now it's works. no more getting too hot. very nice sound with 2sc2922. i loved it.

i didn't change anythings at all. i found c18 was wrong number now i just corrected it, thats all. thanks lots.


i found 2sc2922 sound quality is more btr then 2sc5200.

thank you.

[AndrewT]

what value of C18 caused the oscillation?

[space2000]

hi, the vlu was 4.7nf but it should b 47nf

now the question is, power supply should b 36v. my transformer is 56 volt dc. it functioning well..no abnml heat at all. do you think 56v should b ok or should go down to 36v? i am not good in electronics.

thank you.

[jaycee]

With 56v power supplies you will eventually fry the 2n5401/2n5551 transistors used in the 2nd stage of the amplifier, and the MPSA18 transistors at the input.

[routhun]

2n5401/5551 will be fine only mpsa18s get fried, but they can also be replaced with high voltage replacements

routhun

[space2000]

i am not using mpsa18s, now using bc547c. do you think its ok?

thank you.