ilorev, I ordered printed circuit boards here:
https://www.pcbway.com/project/shareproject/Apex_AX17_amplifier.html
I have checked all TO-92 Transistor they all are fine.
can anyone suggest me voltage reference poins for 41VDC so that i can compare those points for inspection. actually i have a very limited knowledge about Class AB Amplifires.
Note - 1N4148 are dropping arround 0.7V . is it fine?
I hope you guys suggest me any solution .
Thanks.
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@jorgovanko Thanks you so much for your observation . I'll inspect acording to the simulation probes.
three imprented dots on a back side of MJE350 and three imprinted dots on front of MJE340? not likely! use multimeter(Ohm-meter or diode tester) to find base,emiter and colector pins of those transistors that jorgovanko marked in his post..
I dont know how should i react now.
That chinese MJE350 Transistors Level printing was inverted to the Back side. so that this mistake was happend. i have oriented it now correctly and the amp is functioning flawlessly.
Thank you Guys 😊. @jorgovanko @44250 @Extreme_Boky
Audio DIY life lessons:
1) Always use a transistor tester. Try not to buy fake transistors. Purchase transistors from reputable sources, electronics distribution warehouses, i.e. Digikey, Mouser, Farnell, etc…
2) Be suspicious of silkscreening on pcb’s especially if it is a prototype that hasn’t been repeatedly built by multiple members.
3) Trace out the circuit on the pcb and see if it matches the schematic (in this example, where does the collector, base and emitter connect, does it match the schematic?).
All of this takes more time but will ensure a trouble free startup! 👍
Thank you @Extreme_Boky for your eagle eyes! 🤓
Best,
Anand.
Here is my seemingly small contribution to this thread. Inspired by Mile Slavkovic and member XRK971’s rendition of the FX8 presented years back. If you want to learn more details, you can see my post on X’s thread.
Best,
Anand.
Best,
Anand.