500W PA amplifier with Limiter

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I fixed an old Amp 2x250W Rms it has four pairs mj15003 and mj15004 and a Darlington driver 2n5015 with bux67 and 2n3440 with bux66 (I don't remember which is pnp and npn) but I am sure for the numbers
 

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I fixed an old Amp 2x250W Rms it has four pairs mj15003 and mj15004 and a Darlington driver 2n5015 with bux67 and 2n3440 with bux66 (I don't remember which is pnp and npn) but I am sure for the numbers. But I'm not sure for the Vbe if I put it about 500mv transistors get very hot quickly if I keep it about 380mv then temperature is not too high I can touch them what is the best option?

The technician who made it erase the transistor numbers from the protection circuits on purpose.

Service was a challenge for me. I change all caps sound is very clear. for me
Main Voltage is +62V 0 - 62V

The voltage between the base of 2n5015 -2n3440 is 3Volts and between bux67 -bux66 is 2Volts
I am not sure for the Vbe of mj15003 and mj15004 why to put it at 600mv it gets too hot quickly the drivers don't have o good cooling system the out put transistors have a fan might be ok? but driver don't I don't know what to do?
 
hi all

can any one give me some mesurement for b500?

i have 0,47vdc on 5200 transistor base and 0,33vdc on 1943 transistor base. it can open transistor? this mesurement witouth signal.

i need some mesurement samples for b500
5200, 1943, 15033, 15032 and mje340 what they need on base and what is the bias voltage on the bias resistor its 330ohm i think. i think its 1v i was read before but i need to be sure cause too many pages i cannot find it again.

my power voltage is 60vdc.

thank you for answers...
 
B500 based on schematics of H900, but in AB class.
Power supply +/-90Vmax.
hi.i try to find b500 gerber files but i think no one want to share it. i draw it on proteus. if any good of you check it and if all its ok i will share gerber files.

note: i make a little place for coolers so its a little bit bigger then orginal pcb.

thank you.
 

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hi friends.

i find this transformer from old amp and want to use it for b500.

i want use first 2x42Vac for one channel and another 2x42Vac for second channel. i will make this schematic for power but i want to know do i need to connect all GND from 2 different PSU ? or need to work like a 2 different mono amp. which one is better.

thank you.
 

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hi friends..

i want to add input board on b500 amp. but i dont want limiter on input. this is ok if i change shematic from apexaudio like tis and add on my b500? there is signal and input is different pcb. if any one make input from apexaudio is there any changes or values i need to change for my b500?

on schematic there is 2 470n i dont have it and i put there 100n is this ok? :confused::confused:
 

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Pcb inbal

hi friends..

i want to add input board on b500 amp. but i dont want limiter on input. this is ok if i change shematic from apexaudio like tis and add on my b500? there is signal and input is different pcb. if any one make input from apexaudio is there any changes or values i need to change for my b500?

on schematic there is 2 470n i dont have it and i put there 100n is this ok? :confused::confused:
Just for comparing ..
 

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If you like sound of B500, but is to much powerfull for Hi-Fi, consider about this 50W amp.
Regards
Mr. Miles
I have try to make B50 PCB layout without darlington output transistor. I am used c4793/a1837 as as a driver and to c5200/a1943 as output just like B500. Please check for any error.
Regards
 

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