71

EQ573 Equaliser / Re: EQ573-II doesn't play sound

« Last post by andrixb on February 21, 2026, 01:43:23 PM »

Checked. On TP3 is 0.9VAC and TP4 0.8VAC

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EQ573 Equaliser / Re: EQ573-II doesn't play sound

« Last post by JPK on February 20, 2026, 11:36:28 AM »

Also check TP3 and TP4 (the audio goes through them before TP2).

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EQ573 Equaliser / Re: EQ573-II doesn't play sound

« Last post by andrixb on February 19, 2026, 01:02:07 PM »

Thanks. 
I can get 1VAC on TP1, but now it is 0VAC on TP2. Soldier joints look fine. Could it be an issue with the U2 THAT1646?

74

EQ573 Equaliser / Re: EQ573-II doesn't play sound

« Last post by JPK on February 18, 2026, 04:48:29 PM »

Check the value and solder joints of R1...R4, C4, C5, U1, RLY1.
Check the direction of U1, RLY1.
Try swapping U1 with one that you are sure of.

75

EQ573 Equaliser / Re: EQ573-II doesn't play sound

« Last post by andrixb on February 18, 2026, 11:45:53 AM »

Hi

Thanks for the suggestion.

I get a sound in bypass if it is connected to the MP573; nothing gets through otherwise.
On TP1, I get 0VAC. The board is REV2.3B, and the C8 is oriented as in the picture (negative facing the back of the launchbox)

76

AB528 Microphone preamplifier / Re: AB528 DI not working

« Last post by JPK on February 17, 2026, 10:18:48 AM »

Not good! Pins 1, 2, 3, 6 shoulb be at 0V.
Check the solder joints on J4a-J4b.
Look for a solder bridge on U2, on the jack or on the connectors J4a-J4b.


Maybe one of them is no good?
You can check them in circuit with your DMM in diode test mode.

77

AB528 Microphone preamplifier / Re: AB528 DI not working

« Last post by Ritualknive on February 16, 2026, 09:37:01 PM »

They are in correctly. Maybe one of them is no good? Also I’m also now noticing when using the mic/line in the 1200 ohm position there is a constant tapping or ticking type of sound. Only on the 1200 setting. 

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EQ573 Equaliser / Re: EQ573-II doesn't play sound

« Last post by JPK on February 16, 2026, 05:32:44 PM »

Do you get a sound in bypass?
You must try to follow the signal on TP1, TP3, TP4, TP2, as described here.
It will tell you where the signal stops.

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AB528 Microphone preamplifier / Re: AB528 DI not working

« Last post by JPK on February 16, 2026, 05:22:32 PM »

Check that diodes D12 and D13 are installed in the correct orientation: The "k" on the PCB is the ring on the diode.

80

EQ573 Equaliser / EQ573-II doesn't play sound

« Last post by andrixb on February 15, 2026, 02:40:08 PM »

I would need help with this module, please.
The module doesn't play any sound when in both pre and XLR mode.

V values match what is reported here: https://www.soundskulptor.com/forum/index.php?topic=25.0

I checked the tension, and I measured 16V.
Also,  I followed this thread too and around diod D2 I measure -15V / 7V (it goes 7V / -15V when I select XLR) https://www.soundskulptor.com/forum/index.php?topic=362.0
I checked all the solder joints around what is suggested, but the value around D2 measured doesn't change at all.

Thank you