Hi there guys,
Got an Audison SR1Dk which outputs no High-side gate drive.
The driver boards has a very clean input and a very clean low-side output drive wave, but absolutely no High-side output wave.
I changed both HCPL3180 optocouplers, changed the LM219 comparator, changed the SMBTA92 (2D transistor) and checked every single resistor on the board. Everything is original RS-online material.
Anybody got an idea?
Got an Audison SR1Dk which outputs no High-side gate drive.
The driver boards has a very clean input and a very clean low-side output drive wave, but absolutely no High-side output wave.
I changed both HCPL3180 optocouplers, changed the LM219 comparator, changed the SMBTA92 (2D transistor) and checked every single resistor on the board. Everything is original RS-online material.
Anybody got an idea?
Attachments
Do both optocouplers have the same input signal?
What is the DC voltage measured directly across the high-side optocoupler pins 5 and 8?
The high-side could be floating. Connect a load across the speaker terminals to prevent it from floating.
What is the DC voltage measured directly across the high-side optocoupler pins 5 and 8?
The high-side could be floating. Connect a load across the speaker terminals to prevent it from floating.
(Output fets are not installed, forgot to mention)
Good optocoupler reads 15v
Bad optocoupler reads 0v...
Both optocouplers have a good wave input.
Good optocoupler reads 15v
Bad optocoupler reads 0v...
Both optocouplers have a good wave input.
If you measured directly across 5 and 8, you need to determine why there is no voltage on that optocoupler.
Yes.. seems like the HCPL3180 has no voltage on pin 5 and 8.
It's measured across pin 5 and 8.
I'll try to find the causing.
It's measured across pin 5 and 8.
I'll try to find the causing.
I'm having difficulties finding the problem.
(See datasheet attached).
AD2K driver board pin 7 (VB mark) should be the Vcc voltage supply of the optocoupler.
Pin 9 (VSD mark) should be the Vee of the optocoupler
I once had a good working Audison SR1Dk and I measured the driver boards pins. Noted them in a word file.
Pin 7: +-11.63v DC with an output block wave on the oscilloscope.
Pin 9: +-3.11v DC with an output block wave on the oscilloscope.
The potential DC difference between these pins should be the 15v supply of the optocoupler.
There currently is no measurable waves present and also no DC voltage.
I can't conclude how the "VB mark" should get around 11.6v according to the datasheet. Since the "VCC mark" voltage is not present because of the output fets are not being installed.
Does anyone has an idea?
(See datasheet attached).
AD2K driver board pin 7 (VB mark) should be the Vcc voltage supply of the optocoupler.
Pin 9 (VSD mark) should be the Vee of the optocoupler
I once had a good working Audison SR1Dk and I measured the driver boards pins. Noted them in a word file.
Pin 7: +-11.63v DC with an output block wave on the oscilloscope.
Pin 9: +-3.11v DC with an output block wave on the oscilloscope.
The potential DC difference between these pins should be the 15v supply of the optocoupler.
There currently is no measurable waves present and also no DC voltage.
I can't conclude how the "VB mark" should get around 11.6v according to the datasheet. Since the "VCC mark" voltage is not present because of the output fets are not being installed.
Does anyone has an idea?
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Pins 7, 8 and 9 are the floating high-side terminals. They float with the source terminals of the high-side FETs. Without the FETs, there is no square wave.
Thanks for the explaination!
Ok, understood 🙂
When connecting a speaker load to the terminal it should have a reference. But in this case there also won't be any voltage present on pin 7, 8 and 9 I suppose.
Am I correct to say that the supply voltage of the optocoupler of the high side is delivered by the "+VCC mark"?
If so, how can this circuit be checked and measured when only the output fets are connected with the "+VCC mark".
Since this amplifier does not accept output fets yet.
This amplifier should draw 1.51A idle on 12v PS voltage.
It currently draws 1.01A idle on 12V PS voltage.
Ok, understood 🙂
When connecting a speaker load to the terminal it should have a reference. But in this case there also won't be any voltage present on pin 7, 8 and 9 I suppose.
Am I correct to say that the supply voltage of the optocoupler of the high side is delivered by the "+VCC mark"?
If so, how can this circuit be checked and measured when only the output fets are connected with the "+VCC mark".
Since this amplifier does not accept output fets yet.
This amplifier should draw 1.51A idle on 12v PS voltage.
It currently draws 1.01A idle on 12V PS voltage.
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Please use circuit board designations of the components you're referring to. What is the circuit board designation of the optocoupler you're referring to?
The optocouplers are not present on the schematics. The driver board schematics are not included.
The High-Side optocoupler is present on the AD2K driver board.
In the beginning of this post is a photo from the driver board. The HCPL3180 IC on the right side is the one i'm reffering to.
Attached is the schematics from the driver board which I got from another DIYaudio post.
In this photo, the left HCPL3180 is the one i'm reffering to.
The High-Side optocoupler is present on the AD2K driver board.
In the beginning of this post is a photo from the driver board. The HCPL3180 IC on the right side is the one i'm reffering to.
Attached is the schematics from the driver board which I got from another DIYaudio post.
In this photo, the left HCPL3180 is the one i'm reffering to.
Attachments
Yes, VB is directly connected to HCPL3180 Pin8.
HCPL3180 should have 15V between Pin5 and Pin8.
Is it correct to say that the HCPL3180 can't have the correct 15v voltage between Pin5 and Pin8 when the output fets are not installed?
HCPL3180 should have 15V between Pin5 and Pin8.
Is it correct to say that the HCPL3180 can't have the correct 15v voltage between Pin5 and Pin8 when the output fets are not installed?
I'm not sure. On the driver board, there is large SMD diode that's connected to a large SMD capacitor. Are the terminals of that capacitor directly connected to pins 5 and 8 of the optocoupler?
Do you have a 9v battery or some floating supply that you can connect across pins 5 and 8 of the opto-coupler?
Sure! I also have a 14.8v lipo laying around. Would that be a good option? Or would that be risky
Correct!! 😀
On both High and Low-side bank of the output fets gate is now a square wave when there is a music signal.
If it's not the optocoupler..... What could it be...
Output fet gate drive is present.
Output filter inductor is mounted rock solid onto the board. I would not suspect it to be shorted. I will check it now
On both High and Low-side bank of the output fets gate is now a square wave when there is a music signal.
If it's not the optocoupler..... What could it be...
Output fet gate drive is present.
Output filter inductor is mounted rock solid onto the board. I would not suspect it to be shorted. I will check it now
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Try loading the high and low-side locations (one at a time) with a capacitor of about 0.01uf connected across the gate and source. With that load, does the drive signal look OK (or at least consistent) for all of the FET locations?