Good day. The Anthem MRX720 has a charred IT7673 (step-down DC/DC converter, already removed in the picture but not cleaned yet). After removing it there's no more ground short.
The chip provided power to the DSP section so I continued probing around the section and found no more faults, to the best of my ability.
The chip has been discontinued. Through email correspondence with manufacturer they said there is no substitute.
I can only find them on Aliexpress or Ebay from China. I had some bad experience getting counterfeit semis from China, but the manufacturer is iTE from China so I figured there's still chance.
I've placed an order and it will take a while to arrive.
Here's my question,
The boards has several same chips to power individual HDMI sections.
How safe is it to use one of those for testing while waiting for the chip to arrive? When this chip fried the amp powered up fine but no sound.
I figure the HDMI section is more complex and removing one chip would be more complicated than just losing a power rail unlike the DSP section.
They emailed me the PDF datasheet for the chip but it has been plastered with large 'CONFIDENTIAL' words on it so I don't think I can attach it here.
The chip provided power to the DSP section so I continued probing around the section and found no more faults, to the best of my ability.
The chip has been discontinued. Through email correspondence with manufacturer they said there is no substitute.
I can only find them on Aliexpress or Ebay from China. I had some bad experience getting counterfeit semis from China, but the manufacturer is iTE from China so I figured there's still chance.
I've placed an order and it will take a while to arrive.
Here's my question,
The boards has several same chips to power individual HDMI sections.
How safe is it to use one of those for testing while waiting for the chip to arrive? When this chip fried the amp powered up fine but no sound.
I figure the HDMI section is more complex and removing one chip would be more complicated than just losing a power rail unlike the DSP section.
They emailed me the PDF datasheet for the chip but it has been plastered with large 'CONFIDENTIAL' words on it so I don't think I can attach it here.
Attachments
Mmany thanks for posting the issue. Recently I too found the same chip IT7673M shorted on the DSP board of Harman Kardon AVR 161 digital / HDMI assembly board. Unfortunately I can't even buy it from China as I live in India. If you make any breakthrough, kindly let me know. Many thanks
I ordered some from AliExpress and got counterfeit parts. All output voltages were 1.1V
As of now I cannot progress unless I have a donor board with genuine parts. We’re both in the same boat I’m afraid.
As of now I cannot progress unless I have a donor board with genuine parts. We’re both in the same boat I’m afraid.
Many thanks for the reply. Probably, if we know the pinout details of IT7673M, we could use a 1 Volt DC output buck converter utilizing Enable, Ground, Input and output pads of the regulator footprint. The rest of the 4 pins are not required as they only serve the operation of the converter chip. Please explore on this lines. I am unable to see my AVR dead. Unfortunately, i am not successful in finding the pinout details of IT7673M on the net. Thanks
Hi,
I found this vendor that look like they sale the original . Attached it is the link for you consideration.
https://www.utsource.net/itm/p/11765120.html
I found this vendor that look like they sale the original . Attached it is the link for you consideration.
https://www.utsource.net/itm/p/11765120.html
Hi, utsource does have counterfeit issues
https://audiokarma.org/forums/index.php?threads/utsource-sells-fakes.697931/
Since they're not actually selling the items themselves but source from other suppliers, there's always risk for counterfeits.
With $28 shipping I don't want to risk buying from them and suffer more losses. (currency is tanking, so $28 x 5)
Here are some parts that might be considered. We need to know more about the application particulars, i.e. input voltage, load current, output voltage, etc.
https://www.digikey.com/en/products/filter/voltage-regulators-dc-dc-switching-regulators/739?s=N4IgjCBcoBwOxVAYygMwIYBsDOBTANCAPZQDaIAzAJwBsNArCALqEAOALlCAMrsBOASwB2AcxABfQmDAAGRCBSQMOAsTIgALDJgVtzNp0g9+wsZJAAmeo2gK0WPIRKRyFGFRlgq+kBy69BUQkpCgs5W0VlRzUXTQsKUO8WX0NjQLMpODhvCPsVJ3UrGTgYHz8jANNg8Cp3eUiHVWdyOSZzAFobZDzo5stmcUGgA
https://www.digikey.com/en/products/filter/voltage-regulators-dc-dc-switching-regulators/739?s=N4IgjCBcoBwOxVAYygMwIYBsDOBTANCAPZQDaIAzAJwBsNArCALqEAOALlCAMrsBOASwB2AcxABfQmDAAGRCBSQMOAsTIgALDJgVtzNp0g9+wsZJAAmeo2gK0WPIRKRyFGFRlgq+kBy69BUQkpCgs5W0VlRzUXTQsKUO8WX0NjQLMpODhvCPsVJ3UrGTgYHz8jANNg8Cp3eUiHVWdyOSZzAFobZDzo5stmcUGgA
An update:
I calculated the Vout of the IT7673 from the datasheet and came to the measurements. In pencil are the calculated values and in red pen are the measured values.
It seems that I've been getting the correct voltages from the AliExpress chips after all and they might not be fakes.
Example, IC in question is IC1603
Calculated Vout: 1.000V
Measured Vout: 1.014V
However there's no sound coming from speakers and headphone outputs. The AVR amp behaves normally otherwise (all menu items now accessible, can navigate no problem).
I worry some low voltage chips are damaged when pins 2-3 were shorted (Vin-Vout) so they received the full rail voltage before stepdown.
Attachments
Yes, it is quite possible that a shorted microprocessor chip will damage the source voltage regulator, the vice-versa is very unlikely. I too ordered few voltage regulators MP2307 ICs and liquid flux. once received, I shall dismount the defective voltage regulator to check if the DSP chip is intact. i dont know how lucky I am. Regards
One of the fault the owner said was the sound disappeared before the burning smell (IT7673 burning) so its possible Cirrus Logic DSP chip CS49844A-CQZ had failed before burning the voltage reg. However just probing around for shorts doesn't reveal any shorts, visual inspection also doesn't show damages. The DSP chip is quite expensive so we'll see how it goes.