Pearl 3 Burning Amp 2023

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I wasn’t sure if you meant Opamp side A or B so I took both.

Side A

Opamp pin 3 (+IN A) and ground is 0.2 ohm

Between Pin 2 (-IN A) and phono output is 1.02 Mohm

Side B

Between pin 5 (+IN B) and ground is 47.4k ohm

Between Pin pin 6 (-IN B) and the phono output it just keeps climbing up and never settles
Your feedback loop has an issue here. Between + phono out and the - input of op amp pin 6 should read about 36K Ohms. C8 may have some effect over time so try meter in both directions and let settle.
 
I made the modification to the parts and it appears that corrected it. Almost 0mv dc at the outputs.

Here are pictures.
 

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On the boards I bought from another member it looks like there is a trace that connects C8 positive to pin 7. So there is 220 ohms between pin 6 and 7 as well.

I made the below modification. I’ll hook hook everything back up and test it tonight to be sure I have output before confirming that was the exact issue.

I have 3 other pairs of the same boards so I’ll probably try to cut the traces and add jumpers underneath.

The images above show the continuity and the traces. My red probe at the back of the board is touching C8 positive and you can see it attached to Opamp Pin 7 and then to R25.
 

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Phono is finally working after a hard week of troubleshooting…

Thanks to everyone for the help tracking down the issue.

All I need to do is replace the standoffs with some plastic ones after noticing a few times it was shorting out to the chassis giving me a weird voltage.

It is much quieter than the first P3 I built.
 
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@Dneu2011
Sorry about my post #2,978.
Got U1A &U1B confused :giggle:
Funny though...... I have the earlier PCB´s from Sylvain (1.0a), so I went to check the error, you described.
No connection on these boards from C8+ to pin 7.
Try reaching out to @Algar_emi and ask, if the black version boards (mine are red) have this error.
Would be helpful to other members to get this clarified ;)
 
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Hi. Thanks Dennis for the findings, and sorry for those that got the ver1.0a pcb. I made some change to the supply trace routing to try to improve the supply and ground layout on this version (the last one). I took great care to double check the changes but it seems i miss this one, sorry. I’ll send the info, and how to correct the pcb before assembly to those that bought this version. Problem had already be corrected on my design file and next pcb won’t have the error.
For those who bought the pcb from me check your email, I’ll send the mods info shorthly.

note: the error was not on the first red pcb version.
sB
 
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Dneu2011 you can correct the pcb error from under, and resolder the parts at their correct location for a nicer assembled pcb. I will send the info today on how to correct the pcb with two easy steps, done from under the pcb, before or after assembly, to all the member that got the Ver1.0b version.
Please check your private email for details

Sorry again
SB
 
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