Sound Skulptor forums

Build help and troubleshooting => MP566 Tube microphone preamplifier => Topic started by: stevelawaudio on January 27, 2022, 02:24:37 AM

Title: Faulty MP566 - video and audio files
Post by: stevelawaudio on January 27, 2022, 02:24:37 AM

https://drive.google.com/drive/folders/1qz0BCwCTZi6MnlKaGArnJ7fTCu40vqWC?usp=sharing

Hi Everyone.. I was given this MP5.66 (happy!)... but its faulty. 

Attached is a link for some audio files and a short video file of the unit.
Not sure if I've done this right, but let me know either way.

Im about to go through the test document and see what I find, but any help would be great to get this going because Id love to buy another one to use for gain makeup in my summing setup.

Cheers, Steve.

Title: Re: Faulty MP566 - video and audio files
Post by: JPK on January 27, 2022, 03:32:08 PM

First thing to do is to test the voltages.

Title: Re: Faulty MP566 - video and audio files
Post by: stevelawaudio on January 28, 2022, 01:36:30 AM

Tested - 

So, no shorting,
High voltage reads at 225.2v
Low voltage read at -3.1. SMPro little lunchbox, probs why it a little low? 
It's my portable one, the other main rack is a JLM 8 slot.

So, this starts me looking towards a problematic tube ??

S.

Title: Re: Faulty MP566 - video and audio files
Post by: JPK on January 28, 2022, 04:38:22 PM

Can you describe the problem in words, it is no very clear from the audio files?
The LED is blinking. Does it means that the lunchbox PSU is switching on and off? Or is it only the MP566?
Does it pass any audio or none at all?

Title: Re: Faulty MP566 - video and audio files
Post by: stevelawaudio on January 28, 2022, 09:53:19 PM

The blinking only happens with the mp566.. all other modules in the rack work fine. 
The pre passes audio and is usable but after about 5-10 mins the blinking starts, the spikes in the audio output start and it becomes unusable. 

Thanks for your help. 

S. 

Title: Re: Faulty MP566 - video and audio files
Post by: JPK on January 31, 2022, 07:49:41 AM

Can you check if the voltages (225V on TP2, +16V, -16V and TP8 ) are steady during the blinking?