Hello. There was a bootstrap analysis when the FR100 was introduced. MR Mile added this circuit to increase the voltage by a couple of volts on VAS as I understand. I would ask if there would be any advantages to remove the bootstrap and using a stabilized power supply instead. I'm not an electronics expert just an enthusiast.... can I do this modification on the FR50?
Attachments
Hello sir ! I have all the admiration for your cables. Can you share the pcb for headphone amplifier PP12 in gerber or lay6 format? Thank you very much !SR 300 V1.0 TONER TRANSFER FILES
Hi,
Corrected files attached below .
Regards,
Alex
Hello everyone in the group, first I want to thank SR. Mille (Apex) and all members who actively participate in helping with the projects. I'm wanting to assemble the SR100, but I'm having problems getting some components here, so if anyone can help me I'll be grateful:
I can use the tip41 and tip42 pair in the Drivers, as I couldn't find the mje15031 and mje15030, I can also replace the 2n5401 with mpsa92 ?
the bc550 by bc546 and the bc560 by bc556?
And can the 10uf and 1uf polyester capacitor be replaced with a non-polarized electrolytic because I don't think these are in any way accessible?
I only think all ceramic capacitors are 50 volts. I would be grateful if someone could answer me.
Thanks.
I can use the tip41 and tip42 pair in the Drivers, as I couldn't find the mje15031 and mje15030, I can also replace the 2n5401 with mpsa92 ?
the bc550 by bc546 and the bc560 by bc556?
And can the 10uf and 1uf polyester capacitor be replaced with a non-polarized electrolytic because I don't think these are in any way accessible?
I only think all ceramic capacitors are 50 volts. I would be grateful if someone could answer me.
Thanks.
I greet you all. Please help and advice. I can't adjust the bias on the Apex SR50 amp. I changed resistor R30 from 1K to 1K5 and I still don't have about 2V voltage on BD139. Please advise me what to focus on and where the problem could possibly be. Thank you very much and have a happy and merry Christmas. I use layout Coolet.
Vbe_multi (Q11, P1, R29 and R30) is most likely no working "properly".
You made change for R30 from 1K to 1K5 with no visibile BIAS changes
i.e. differences in Vbe_multi min-max adjusting voltages (voltage measured on C8 adjusting P1)
For DualEmitterFollower DEF OPS you need aprox. >4xVbe = >2,5V on C8
When you adjust P1 to the one off the two extrems (0R and 1K), for P1->0R, what is your voltage measurement on C8?
C8 voltage = Vbe_multi (V) = Vbe * (1 + R30/(R29+P1)) ; Vbe= aprox 0,65V
Check R29 value!
Maybe is not 220R but higher in value, so Vbe_multi voltage cant reach necessary max level (more then 2,5V on C8)
Measure voltage differences on VAS R28 100R and on VAS current mirror R26 R100 (you must read on DMM aprox. 0,85V...1V on 100R => 8,5...10mA)