I Sunny, R49 is R18 in your blue pcb, right side of Q6. But you should see what Mister Mile (APEX) say, because he is the Boss 🙂
Final I on sr200. Version 3.1 but there is no bias on emmiter resistor . But bd139 on 2.2 volt . Without speaker heatsink little hot .but when I contacted speaker playing music heatsink imba hot I cannot touched .just like burning
I cannot it got bias on emmiter resistor .it's showing 0.0 volt but my heatsink is very hot.
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vzaichenko greetings sir, sound is not good from speaker.. when I turn trimpot then current up down on bd139. But bais is big zero.
Hi Sunny, that's the point - bias is zero but the heatsink is very hot most likely means either oscillation or some mistakes in assembling the boards (like TO-126 transistors soldered backward for example, etc.). SR200 is a mature design, built many times, so being built with no mistakes it is expected to work no problem.
Anyway, an oscilloscope is the best friend of a DIY builder, even some simple one. It makes sense to have it always connected to the output until you are sure everything works perfectly - you can catch an oscillation early and react accordingly, you can also see the oscillation parameters, giving you ideas on its nature.
Testing amplifiers with no scope is like doing it with your eyes closed. Not enough information for troubleshooting.
Anyway, an oscilloscope is the best friend of a DIY builder, even some simple one. It makes sense to have it always connected to the output until you are sure everything works perfectly - you can catch an oscillation early and react accordingly, you can also see the oscillation parameters, giving you ideas on its nature.
Testing amplifiers with no scope is like doing it with your eyes closed. Not enough information for troubleshooting.
That's what I thought. I recommend getting at least something very simple, like this one:
Fully Assembled DSO138 Open Source 2.4" TFT Digital Oscilloscope (1Msps) with FREE Probe
$21.24, free shipping.
Much better than no scope 😉
Greetings sir...
Regarding SR300 will you recommend it in Class H version i have 10 pairs of MJ21193/4 i am thinking to make 5pairs per channel what stepper can you recommend?
i have 4x43VAC traffo... thank you...
regards
sam
Use stepper from HX11 or from BA2000. or use class G from B2000.
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how i love to make class TD like in this mackie or labgruppen but my skills aren't enough for it. by the way i am interested in this 140VDC supply with 15pairs of output. i will be making one of this soon...
Thank you for the quick reply...
regards
Sam
i have assembled two boards of SR300 and tested them today. output voltage is about 10Vrms,bias per cold pair is 30mA 10mV across 0,335Ohm and it is stabile. with heatsink about 60 degrees Celsius it reaches 12mV or 35mA per pair. i think i have made a mistake at Signal LD circuite because it is lighting with no input-output signal,i mist check that. power and clip LED work just fine. also,i have not yet tested protection that is on an amplifier pcb.
i have tested it with 10r in paralell with 470nF and it does not showing any oscilations. it "rings" a little bit but i have some troubles with my tone generator,so osciloscope shows same ringing at amp input and output. when i solve that tone generator trouble i will show some more pictures here. anyway,amp worked with 10Vrms and square signal at output ,on 10r paraleled with 470n for about hour and a half,and survived with no troubles.
next is test with no security-light bulbs in series with positive and negative power supply,and than if everything is all right there will be first audio testing.
i have tested it with 10r in paralell with 470nF and it does not showing any oscilations. it "rings" a little bit but i have some troubles with my tone generator,so osciloscope shows same ringing at amp input and output. when i solve that tone generator trouble i will show some more pictures here. anyway,amp worked with 10Vrms and square signal at output ,on 10r paraleled with 470n for about hour and a half,and survived with no troubles.
next is test with no security-light bulbs in series with positive and negative power supply,and than if everything is all right there will be first audio testing.
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