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Digital / Re: Audio from different computers
« Last post by sajunky on Today at 03:55:04 AM »
macOS Big Sur Update Bricking Some Older MacBook Pro Models
Sunday November 15, 2020 5:33 am PST
I am now busy with MBP 2017, it is affected with the same issue, killed by Catalina ( I think it was January update). Laptop came out from the Apple authorised service with missing some screws and grounding brackets. Without brackets cables a likely to pickup a noise. Machine has some minor issues, a camera is dead. I am holding repairs till receiving these parts. In meantime I am playing with and learning MAC OS, what a pleasure. :)

Motherboard was declared dead by the technicians, but I did apply fixes which are known to to help of MBP 2013-2015 and a laptop was working very stable running the latest October release of 10.15.7 till about last week. All system updates had been disabled, including security updates and even checking for updates to not disturb every day. Despite of the settings I received notification about security update that surprised me. I was playing for few hours, then restarted OS and ... then machine went into an endless black screen restart loop. After a reset laptop started to shutdown randomly (python script wasn't helping anymore). Interesting observation you will hear now. I have another admin login account with identical apps and settings. I disabled all network access and after reset started login to this account instead. No more random shutdowns!!! Machine is super stable again! Returning to the old account, problem is back.

A conclusion is that instruction to give a trouble on the next boot comes from the user space software, not system level. Apple is technically able to simulate a hardware failure. I investigated schematics and found as following:

Problem is at the USB C power regulator. This is a complex regulator (CD3215A) due to the USB PD (20V for charging) and also a Thunderbolt functionality implemented in MACs. It is a fully programmable device. It doesn't have its own firmware, it is loaded dynamically from the Thunderbolt section of the EFI ROM during boot time. MAC has four USB C ports, each chip controls a single port, two controllers are daisy chained for passing the same firmware received through the I2C interface (but it is not relevant).

What happens when Apple is pushing new OS update? The update may come with a new firmware. It is different to the Windows machine, as board manufacturer supply firmware, not Microsoft. In a MAC world firmware image for flashing is not available separately anymore, it is bundled with software updates.

Now I am considering such scenario where EFI update is embedded. Software application instructs kernel to perform firmware update on the next boot. It is done successfuly and machine is restarted to perform a next stage: updating OS. In my case something goes wrong and with a new firmware regulator starts malfunctioning, generating lot of heat before power management kicks off (touching the radiator is almost burning), cooling down later after booting to the login page successfuly. However it may enter endless booting loop with a blank screen or may randomly shutdown after booting. The next boot report CATERR detected, no MCA data found. Do google search, you wil find it is a sympthom of a hardware failure.

What happens after reseting SMC/nvram? A backup firmware is restored, if you boot in recovery mode or from an external device or even to a different login account, machine works perfectly. I am sure you won't believe this....
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General Discussion / Re: AUDIO MASTER - SCHALK HAVENGA
« Last post by JoziNic on November 28, 2020, 11:48:35 PM »
Play list for @JoziNic was (unfortunately not enough time for more);

Stevie Ray Vaughan & Double Trouble - Tin Pan Alley (Couldn't Stand the Weather; Epic US 1984)
Carla Bley - Life Goes On (Life Goes On; ECM Germany 2020)
Tsuyoshi Yamamoto Trio - The Way We Were (Autumn in Seattle; FIM US 2011)
Holly Cole - Take Me Home (Temptation; Blue Note US 1995)
All I can say is that they sounded like totally new songs to me compared to how they do on my system. Absolutely UNREAL


Sent from my iPhone using Tapatalk
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Media/CDs/LPs/Lossless/DVDs/Bluray/MP3/Games, etc / Re: Now playing...
« Last post by Hi-Phibian on November 28, 2020, 11:37:34 PM »



 
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Headphones / Re: Value for money audiophile headphones
« Last post by Doge on November 28, 2020, 11:35:53 PM »
Burned it in for over 70 hours hoping it would 'open up' but I've given up because anything else I've had has sorted itself out by now, and any improvement would have to be significant to change my mind. I also used the same interconnects for both DACs.

I'm not saying it's a bad DAC but single-ended it certainly isn't soncially as good as the slightly more expensive Topping as either a DAC or a combo.

Again; these might not be in the same class in other regions of the world so adjust accordingly. Still my money's on there being better sounding sub $130 DACs out there because the money didn't go into the build or the balanced architecture.
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General Discussion / Re: AUDIO MASTER - SCHALK HAVENGA
« Last post by FranZAR on November 28, 2020, 11:22:09 PM »
Thanks for the feedback Frankie  :2thumbs:

Play list for @JoziNic was (unfortunately not enough time for more);

Stevie Ray Vaughan & Double Trouble - Tin Pan Alley (Couldn't Stand the Weather; Epic US 1984)
Carla Bley - Life Goes On (Life Goes On; ECM Germany 2020)
Tsuyoshi Yamamoto Trio - The Way We Were (Autumn in Seattle; FIM US 2011)
Holly Cole - Take Me Home (Temptation; Blue Note US 1995)
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Media/CDs/LPs/Lossless/DVDs/Bluray/MP3/Games, etc / Re: Now playing...
« Last post by Scubadude on November 28, 2020, 10:54:22 PM »
Havent posted here in a while ... sheer brilliance is our Dan!



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Headphones / Re: Totalling digging....
« Last post by Scubadude on November 28, 2020, 10:51:40 PM »
@Dhiveshan recently listed a T1 .. not sure if it was sold.  The T1 is an incredible headphone, right up there with the HD800 as one of the finest dynamic headphones ever made.  Both need careful attention to get system matching just right, and both reward in spades when you do.
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DIY for audio / Re: Musical Fidelity F15 repair "nightmare"
« Last post by Gerlach on November 28, 2020, 10:06:44 PM »
Thanks @fdlsys

Jip, did check the PSU  without anything connected it, stable all the way.

Left channel board is the working one, Jip, i removed the the left channel board and connected to the right side of the PSU, it's working and stable and not heating up. Connect the re build right side board to the left side of the PSU, PSU starts heating up and the re build board heating up to and the speaker out put volts all over the place.

Good point that, will measure the the good channel board and see what i can find.

Will do the bulb test, problem is, the 10w white ceramic resistors on the PSU gets so warm that they start smoking of the heat.

Service manual???? that's the massive problem, you cant find them. There some Chines/Japan sites where the guys repuild the a1000 units. But something bugging me , the A1000 units had a external power supply and to what i can see is, they run a lower volts.

When you check the Pre board and the PSU board on my one, it shows version 2. Something is telling me, when this unit went up to JHB in the pass for a repair, they swap the boards out with the A1000 board or maybe not?

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Open Talk / Re: Challenge: Identify audiophile equipment
« Last post by ingenieus on November 28, 2020, 09:42:21 PM »
I can't identify the gear, but there sure is a lot of it standing around. I wonder if any of it is included in the sale.
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DIY for audio / Re: Musical Fidelity F15 repair "nightmare"
« Last post by fdlsys on November 28, 2020, 09:41:55 PM »
No, no, no...
First check your PSU, nothing connected to it.
If PSU is good and stable, you have one healthy channel, right? Connect only that one, observe the PSU again.
If all good and stable, measure, learn from the good channel.
Then power up the suspect channel (disconnect the good channel) with light bulb in series. See what causes the excessive current draw. It might be as simple as current limiting resistor (or a few) somewhere that has drifted way down low. It happens more often than people think.
Do you have the service manual?
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