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MP573 Microphone preamplifier / Re: bruit de pok aleatoire sur entrée micro

« Last post by JPK on Today at 11:33:54 AM »

Est-ce que le bruit se produit sans micro connecté ?
Micro statique ou dynamique ?
Le niveau du pok dépend-il du gain, de l'impédance, de la polarité ?
Le bruit apparait-il sue l'entrée DI ?

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MP573 Microphone preamplifier / bruit de pok aleatoire sur entrée micro

« Last post by ericvick on Today at 09:48:28 AM »

bonjour
le preampli marche tres bien mais j'ai des bruits de pok de temps en temps sur l'entrée micro.
une piste de recherche svp
merci
musicalement
eric

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EQ573 Equaliser / Re: Signal going through the unit but it doesn’t effect the sound

« Last post by Colindsv on November 18, 2025, 06:31:12 PM »

Thanks, ordered.

I’ll update when I put it in

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MP566 Tube microphone preamplifier / Re: MP566 no DI sound

« Last post by JPK on November 18, 2025, 03:30:11 PM »

It is very likely Q1. It is a device which is very sensitive to static electricity before being soldered. It could be damaged.
Check if the voltage across D2 drops from 24V to 0V when inserting a jack plug. If not, change Q1. Handle the new one with your body grounded (no shoes on). If the voltage does drop then it is the relay.

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EQ573 Equaliser / Re: Signal going through the unit but it doesn’t effect the sound

« Last post by JPK on November 18, 2025, 03:15:00 PM »

It looks like you need to replace RLY1.
Contact us here for a replacement.
Or get one more quickly, locally:
https://www.mouser.com/ProductDetail/Panasonic-Industrial-Devices/TQ2-24V?qs=HLLy2pIPwuvqeFYAg5JtGw%3D%3D
https://www.digikey.com/en/products/detail/panasonic-electric-works/tq2-24v/251775

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MP566 Tube microphone preamplifier / MP566 no DI sound

« Last post by TomT on November 16, 2025, 11:44:42 PM »

Hi,

I assembled my (second) MP566.
Everything works fine, except for the DI.

When I insert a jack, I keep receiving the sound of the Mic Input.

I read somewhere at the forum, it could be that the Q1 is damaged?

How can I find out?

Thanks in advance!
Tom

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EQ573 Equaliser / Re: Signal going through the unit but it doesn’t effect the sound

« Last post by Colindsv on November 16, 2025, 10:01:15 PM »

Power off, across the diode but with your DMM in ohm mode. You should read around 2k.

Ok power off measuring resistance with a meter probe on either side of D1 gives 0.0ohms
D2 gives 2.8kohms

 both relays and diodes were double checked for proper orientation and are ok. 

Also I did not have to desolder/resolder the relay

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EQ573 Equaliser / Re: Signal going through the unit but it doesn’t effect the sound

« Last post by JPK on November 16, 2025, 09:38:08 AM »

Power off, across the diode but with your DMM in ohm mode. You should read around 2k.

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EQ573 Equaliser / Re: Signal going through the unit but it doesn’t effect the sound

« Last post by Colindsv on November 16, 2025, 02:20:15 AM »

It looks like the relay coil is disconnected.
Check that the relay is in the correct direction (white line on the left).
Can you measure the coil resistance across the diode?
Did you have to desolder and remove the relay during assembly?
The relay may be damaged, try to replace it.

How do I measure coil resistance across the diode?

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EQ573 Equaliser / Re: Signal going through the unit but it doesn’t effect the sound

« Last post by JPK on November 15, 2025, 05:07:11 PM »

It looks like the relay coil is disconnected.
Check that the relay is in the correct direction (white line on the left).
Can you measure the coil resistance across the diode?
Did you have to desolder and remove the relay during assembly?
The relay may be damaged, try to replace it.