Tried the headunit with RCA, no more protect when signal is passed through.
Hooked up a little 4ohm speaker and when the relays engaged the protect light would come on (no protect prior to relay engaging as previously it would go into protect about a second after remote is turned on), but the tone would still play through the speaker although quiet. It would also cut out for half a second, every few seconds. Volume would change according to gain or headunit volume but still would not be loud. (current pull did not change during this)
Checked speaker output without the speaker connected (no protect at all), shows this wave at gain all the way down and headunit volume at 0 (attached). When gain or headunit volume increased, this wave would rise up, jump to 0v, rise up, jump to 0v as if there is some sore of DC on it. (I think it looks like rail voltage building iirc?)
Hooked up a little 4ohm speaker and when the relays engaged the protect light would come on (no protect prior to relay engaging as previously it would go into protect about a second after remote is turned on), but the tone would still play through the speaker although quiet. It would also cut out for half a second, every few seconds. Volume would change according to gain or headunit volume but still would not be loud. (current pull did not change during this)
Checked speaker output without the speaker connected (no protect at all), shows this wave at gain all the way down and headunit volume at 0 (attached). When gain or headunit volume increased, this wave would rise up, jump to 0v, rise up, jump to 0v as if there is some sore of DC on it. (I think it looks like rail voltage building iirc?)
Attachments
Did you try is with the B+ voltage back up around 13v? The low voltage was to check the drive circuit at full duty cycle.
When you have output but at a reduced level (when it shouldn't be low), what's the amplitude of the rail-rail square waveform at the output transistors?
What is the audio level at the input to the relay?
What is the audio level at the input to the relay?
The output fets showed High/Low DC (on corresponding sides) on one pin.
Same as speaker output on another pin (this flashed on my scope a fraction of a second, every second or so. 10x probe. Blurry picture as this is a screenshot from a video, it was the only way to capture this weird wave I saw as I don’t think my scope can take “screenshots” as I have seen other do)
The third pin would make the amp go into protect so i think it’s the voltage sensing pin I forgot the name of?
Something I noticed is that the previous times the amps went into “protect” the green power LED was fully illuminated and the red protect LED was dimly lit (wouldn’t be on at all when I said it wasn’t in protect)
When I probed the fet pin that made it go into protect I head an audible relay click, the power LED went out and the protect LED turned on and was brighter than previously
I forgot which pin did what as this was a few hours ago
Same as speaker output on another pin (this flashed on my scope a fraction of a second, every second or so. 10x probe. Blurry picture as this is a screenshot from a video, it was the only way to capture this weird wave I saw as I don’t think my scope can take “screenshots” as I have seen other do)
The third pin would make the amp go into protect so i think it’s the voltage sensing pin I forgot the name of?
Something I noticed is that the previous times the amps went into “protect” the green power LED was fully illuminated and the red protect LED was dimly lit (wouldn’t be on at all when I said it wasn’t in protect)
When I probed the fet pin that made it go into protect I head an audible relay click, the power LED went out and the protect LED turned on and was brighter than previously
I forgot which pin did what as this was a few hours ago
Attachments
Do you see constant audio on the input of the audio driver board when the amp goes into protect?
Is the power supply shutting down (losing drive pulses on PS FETs) when the amp goes into protect?
Is the power supply shutting down (losing drive pulses on PS FETs) when the amp goes into protect?
Is the remote (alone) still on the second supply?
Does it go into protect if you drive signal into it with no load?
Does it go into protect if you drive signal into it with no load?
Yes, around 13.5v, same as B+ power supply
No
Only sometimes now and only on initial startup (partially lit protect)
Only times its ever gone into full protect is when I probed the pin on the output fets (I think gate?)
No
Only sometimes now and only on initial startup (partially lit protect)
Only times its ever gone into full protect is when I probed the pin on the output fets (I think gate?)
Are you using any sort of current limiter (you shouldn't be, at this point)?
Does anything change if you take remote voltage from the larger supply?
Does anything change if you take remote voltage from the larger supply?
No, only a 10am fuse on B+
Nothing changes when using larger supply for B+ and remote
I did check output fets on power and what I will call “half protect” (power LED on and protect dimly lit). Normal power (power LED only) the output fets only seem to have DC on the 2 outer pins and nothing on middle pin. In half protect, one outer pin has oscillating current, other side has DC, middle seems to have a larger oscillation
Half protect occurs when headunit volume or gain is increased
Nothing changes when using larger supply for B+ and remote
I did check output fets on power and what I will call “half protect” (power LED on and protect dimly lit). Normal power (power LED only) the output fets only seem to have DC on the 2 outer pins and nothing on middle pin. In half protect, one outer pin has oscillating current, other side has DC, middle seems to have a larger oscillation
Half protect occurs when headunit volume or gain is increased
All ICs have the same numbering scheme. The function may be different but the numbers are the same.
This is an LM2904/NJM2904. It's given on the diagram.
This is an LM2904/NJM2904. It's given on the diagram.
