Hey,
Got my hands on a Audison SR1D. Dont know the previous history but it came in with a blown psu section and someone had already tried to fix it with no results.
Psu had blown output fets and burned buffers. Since the pcb also had some damage i had to be a little innovative and used through hole pnp/npn for psu buffers. Got the psu up and running fine but output section was still faulty. I took off the IRS20124 and know the amp powers up fine. Output fets and buffers transistors all check out fine. Since theres chip shortage accross the world(atleast in the eu) i ordered 4pcs of IRS20124 from china. Now when i power up the amp im getting nice drive wave on the high side for the first 5 seconds, after that it goes silent. When i connect a load to the amp output to kick start it(10ohm resistor) the coils start whining and im getting a nasty signal on high side but still nothing on the low side, signal is there for around 10s seconds and after that goes silent again. Also the diode that feeds irs20124 with vcc gets really hot(was also burned out when the amp came in). The LM319M that feeds driver chip with pwm seems to works correctly and sends a nice small pwm signal that rides along close to negative rail to pin nr 1 of IRS20124. So pwm generation section with preamp seems to work well. Now only thing on my mind is that how possible is that i got fake IRS chips from china? I ordered 4pcs and all of them behave excactly the same. Or there is something that im missing here. Anyone else come across with similar problem?
Got my hands on a Audison SR1D. Dont know the previous history but it came in with a blown psu section and someone had already tried to fix it with no results.
Psu had blown output fets and burned buffers. Since the pcb also had some damage i had to be a little innovative and used through hole pnp/npn for psu buffers. Got the psu up and running fine but output section was still faulty. I took off the IRS20124 and know the amp powers up fine. Output fets and buffers transistors all check out fine. Since theres chip shortage accross the world(atleast in the eu) i ordered 4pcs of IRS20124 from china. Now when i power up the amp im getting nice drive wave on the high side for the first 5 seconds, after that it goes silent. When i connect a load to the amp output to kick start it(10ohm resistor) the coils start whining and im getting a nasty signal on high side but still nothing on the low side, signal is there for around 10s seconds and after that goes silent again. Also the diode that feeds irs20124 with vcc gets really hot(was also burned out when the amp came in). The LM319M that feeds driver chip with pwm seems to works correctly and sends a nice small pwm signal that rides along close to negative rail to pin nr 1 of IRS20124. So pwm generation section with preamp seems to work well. Now only thing on my mind is that how possible is that i got fake IRS chips from china? I ordered 4pcs and all of them behave excactly the same. Or there is something that im missing here. Anyone else come across with similar problem?
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What diode (exact part number) did you use to replace the one that failed?
Is this the diode that connects between VCC and VB?
Is the 12v regulator feeding VCC within tolerance?
Is this the diode that connects between VCC and VB?
Is the 12v regulator feeding VCC within tolerance?
Since i removed the old diode a long time ago i had no idea what it was. I just dropped 1n4007 in there because i only remembered it being a 1A diode.
Also vcc doesnt look right. With irs20124 removed i'm reading -25.2V on 11V supply. And that diode does connect between VCC and VB.
Also vcc doesnt look right. With irs20124 removed i'm reading -25.2V on 11V supply. And that diode does connect between VCC and VB.
The 4007 is too slow. You need to use a fast recovery diode that can easily withstand the full rail to rail voltage in the amp.
I dont know if only that diode is the reason but i got the amp to switch finally. Tried a few different diodes and currently RGP10A sits in there, doesnt heat up or anything but amp is still not working correctly. The waves look okay but im having a weird noise/whine in the background. Around 8-10khz and fluctuates a little bit but its quite loud. Noise seems to be coming from irs20124 because i swapped buffer transistors and checked the diodes and all check out fine. Also when touching HO pin of the irs20124 the noise frequency changes. Added a picture what that noise looks like from speaker terminal.
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Are you using a subwoofer or a full range speaker?
Does it sound like this:
http://www.bcae1.com/temp/cooleditmixedoscillator01.wav
Does it sound like this:
http://www.bcae1.com/temp/cooleditmixedoscillator01.wav
Using 8" woofer. It's like(lets say 8khz) sine wave with a little bit of distortion. From the speaker frequency doesnt change just the oscilloscope jumps between 8-10khz. Amplifier does produce sound when i apply signal to rca's but it sounds distorted and that "8khz noise" is in the background also.
Exactly the same. Also cant turn the volume up too much because it starts to distort. I ordered a few new drivers incase i managed to hurt all the "old" ones with faulty components still on the pcb.
So, waking up the old thread. Got new driver fitted finally but nothing changed. Also since the amp has been sitting for a long time on the shelf i had forgotten that output section had been "repaired" too. One of the high side fets is replaced previously because its from a different batch. Also one resistor R170 looks a bit different from the others so its probably replaced too. I swapped out high side / low side buffer transistors just to check if anything changes. They all test out fine but maybe one of them leaks or something, but no change. Then to be 100% sure i even fitted new ones but still no change. Then i removed the output fets to compare them and i noticed that when i only install 1 fet per bank the amp actually works. Noise is gone. As soon as i add second fet to high side the noise is back(also current jumps from 0.7A to 1.5A). Since all the buffers and etc check out fine i took diodes off the board. They checked out fine with a dmm so when fitting them back in i swapped high-low side with each other and suddenly amp is in protect. Measured diodes again and one was shorted. Also i remembered that when i blew hot air on the diodes(1 fet per bank) then the noise came back and as soon as they cooled down the noise dissappeared. Is it possible that i had a leaking diode or something that might have caused it? Since i need new diodes anyway can someone confirm if S18 smd diode is DFLF1800?
Oh and i have 10A bench psu but amp started to distort at around 2A.
Oh and i have 10A bench psu but amp started to distort at around 2A.
Attachments
It may be but the Diodes datasheet shows a Y and M code that yours doesn't have.
How is the diode being used (what other components is it connected to) in the amplifier?
How is the diode being used (what other components is it connected to) in the amplifier?
Yes i noticed that too.
Diodes cathodes are connected to each buffer transistor's emitter, low side anodes connects to LO of the driver and high side anodes connects to HO of the driver.
Edit: Anyone happens to have a schematic for this amp or can identify diodes D23-D26 with S18 marking?
Diodes cathodes are connected to each buffer transistor's emitter, low side anodes connects to LO of the driver and high side anodes connects to HO of the driver.
Edit: Anyone happens to have a schematic for this amp or can identify diodes D23-D26 with S18 marking?
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Actually it might have been like in your schematic. Even component values might match thinking from the top of my head.
