Is it stable 0.2 ohm?
Can you measure amp input (R301) and output at same time with different oscilloscope channels? Do not connect anything else to the amp input than probe.
Can you measure amp input (R301) and output at same time with different oscilloscope channels? Do not connect anything else to the amp input than probe.
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Stable 0.2Ohm 👍
DC:
CH1 Input (Top signal)
CH2 Output (Bottom Signal)
Well I don’t know if the video is necessary but I’ll put it in here anyway maybe it will help in the future with voltage readings or something. The input is steady no change and the output not so stable.
DC:
CH1 Input (Top signal)
CH2 Output (Bottom Signal)
Well I don’t know if the video is necessary but I’ll put it in here anyway maybe it will help in the future with voltage readings or something. The input is steady no change and the output not so stable.
Sorry, I forgot to write that input is needed to measure with about 29 dB (30 times) more sensitive settings than output, to get something meaningful.
29 dB is amplifier amplification.
This measurement can help to understand is something (IC201 mainly) generating signal to input or amplifier is generating the signal itself.
As I understand both had 10V scale in last video.
29 dB is amplifier amplification.
This measurement can help to understand is something (IC201 mainly) generating signal to input or amplifier is generating the signal itself.
As I understand both had 10V scale in last video.
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No problem, here is the input on 0.1V scale and the Output on 10v scale, seems to be sufficient enough to demonstrate what’s happening. The signals are the same.
Here’s a video for help in the future maybe.
Here’s a video for help in the future maybe.
Can you make measurement where one channel is on amp input and other is on IC201 pin 7 and second measurement where other channel is on R105 upper pin? Tune scaling to 0.1 V or smaller until some voltage shape is seen.
Sure 👍
Here are the results of pin 7
I didn’t make a video for top of R105 since there just wasn’t any signal no matter how low the voltage scale could go it was just a straight line
Here are the results of pin 7
I didn’t make a video for top of R105 since there just wasn’t any signal no matter how low the voltage scale could go it was just a straight line
I mean R105 top pin by schematic, what must have close signal to amp input. Important is witch is bigger.
Or you measured R105 pin what is grounded?
Or you measured R105 pin what is grounded?
I am confused, on last video and video before Input signals are totally different, scaling is 5 times more sensitive on last and signal have about 5 times less amplitude.
I presume left volts/div is CH1 and it is on both videos upper line?
I presume left volts/div is CH1 and it is on both videos upper line?
It is 🤔 I just noticed that too, here I’ll redo the following:
Input - Output
Input - R105
Input - Pin 7
I apologise for the late response and the odd readings this has really got me confused. I really hope this helps.
The first readout on the oscilloscope shows CH1 voltage scaling the second readout is CH2 scaling
Input - Output
Input - R105
Input - Pin 7
I apologise for the late response and the odd readings this has really got me confused. I really hope this helps.
The first readout on the oscilloscope shows CH1 voltage scaling the second readout is CH2 scaling
OK, this is now reasonable. From measurements is not possible to understand what signal is bigger, input or R105 and it is not your problem. If I calculate, then difference can be about 1%, what is not possible to see on oscilloscope screen.
IC201 must work as integrator, it must filter O/P signals with very low frequency low pass filter, but on pin 7 it had more high frequency components than on O/P, so probably it is not OK or C105 is not OK or had bad solder on connections.
This pin 7 high frequencies components are not seen on input, they are divided down by R108 and some other component failure is creating this low frequency input signal, possible failed parts are D101, D103 and Q101.
I personally suspect D101, D103, for testing you can just solder out pin of them what is connected to input. This diodes are only for soft clipping, what is not needed function. On one of my 216 amps one of this diodes created big distortion, so I removed them all. On other amp distortion was created by mute transistors (Q101 and Q102) I removed them also, but this remove will make amp protection weaker, as it is no more enable to mute too high input signal.
IC201 must work as integrator, it must filter O/P signals with very low frequency low pass filter, but on pin 7 it had more high frequency components than on O/P, so probably it is not OK or C105 is not OK or had bad solder on connections.
This pin 7 high frequencies components are not seen on input, they are divided down by R108 and some other component failure is creating this low frequency input signal, possible failed parts are D101, D103 and Q101.
I personally suspect D101, D103, for testing you can just solder out pin of them what is connected to input. This diodes are only for soft clipping, what is not needed function. On one of my 216 amps one of this diodes created big distortion, so I removed them all. On other amp distortion was created by mute transistors (Q101 and Q102) I removed them also, but this remove will make amp protection weaker, as it is no more enable to mute too high input signal.
Probably IC201 can also be OK. Measure for comparison its output on pin 1 and power on pins 4, 8, maybe just power is very noisy.
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Changed C105 since I had one in stock then measured Power on pin 4 and 8 and got straight clean line of DC voltages and Pin 1 is also clean and straight.
I’m not quite sure what you mean by this ‘for testing you can just solder out pin of them what is connected to input.’
I’m not quite sure what you mean by this ‘for testing you can just solder out pin of them what is connected to input.’
Removed D101 and D103 and replaced C105 the results are practically the same as previously with these
Input - Output
Input - R105
Input - Pin 7
Input - Output
Input - R105
Input - Pin 7
Connect RCA input to the ground, do you then still get signal on amp input (R301) and amp O/P terminal?
If you get less signal or nearly no signal, remove the ground connection and solder out Q101 and measure again input (R301) and amp O/P terminal.
Had you changed IC201 earlier to AD712JNZ or it is original?
If you get less signal or nearly no signal, remove the ground connection and solder out Q101 and measure again input (R301) and amp O/P terminal.
Had you changed IC201 earlier to AD712JNZ or it is original?
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Yes I still get signals on both, just so I know I didn’t do anything wrong the way I did was an RCA to AUX then I put my AUX to my oscilloscope earth ground.
The signal seems the same but just to make sure I'll solder out Q101 I'll get back with the results in a bit, I have changed IC201 to a AD712JNZ, I still have the original though.
Sidenote> This testing is being done with D101 and D103 still out.
Sidenote> This testing is being done with D101 and D103 still out.