41

MP566-II Tube microphone preamplifier with HPF / Re: Possible ICs fried MP566-II

« Last post by spurton@gmail.com on May 21, 2026, 10:10:19 PM »

It looks like R3 is scorched. I measured it and it’s open loop. I Noticed the left lead looks burned. 

42

TS500 Tape Simulator / Re: TS-500 VU meter setup

« Last post by JPK on May 21, 2026, 04:36:25 PM »

TAPE SAT to the left (-).
The other switches have no effect on this setting.

43

MP566 Tube microphone preamplifier / Re: 5.66 Problems

« Last post by JPK on May 21, 2026, 04:29:03 PM »

what do you mean by sequenced?
When you turn on power, the high voltage comes up after 2-3 seconds and the heater voltage after 5-6 seconds.

Check that you don't have any DC voltage on TP4.
Try to follow the signal: https://www.soundskulptor.com/forum/index.php?topic=209.msg981#msg981

44

TS500 Tape Simulator / TS-500 VU meter setup

« Last post by giveaway on May 21, 2026, 12:54:12 PM »

Hi!
The setup guide does not seem to mention the state the saturation and bias switches should be in when calibrating the VU meter. Does anyone know?
Sorry if this info is available somewhere, but I have searched quite a bit without finding it.

45

MP566 Tube microphone preamplifier / Re: 5.66 Problems

« Last post by MRMNW on May 20, 2026, 05:57:34 PM »

Thanks, what do you mean by sequenced?

It's one of your 501 Chassis, but does the same in my API lunchbox too.

46

MP566 Tube microphone preamplifier / Re: 5.66 Problems

« Last post by JPK on May 20, 2026, 05:47:34 PM »

The voltages are OK.
Check that the 2 voltages are sequenced and come up after a few seconds.
Check that it is not the chassis that is loaded too much. What brand is it? Did you add more modules recently?

47

MP566 Tube microphone preamplifier / Re: 5.66 Problems

« Last post by MRMNW on May 20, 2026, 01:56:41 PM »

I get 222v and -5v

48

MP566 Tube microphone preamplifier / Re: 5.66 Problems

« Last post by JPK on May 19, 2026, 04:14:54 PM »

Can you do the high and low votages check in the test guide, steps 3 and 4?

49

SK49 Multi-patern Tube Microphone / Re: SK49 pair on a live orchestra

« Last post by JPK on May 19, 2026, 04:09:22 PM »

The recording sounds fantastic, thank you so much for sharing!
We love seeing our kits built so well and put to such great use. Thanks for the support, and happy recording!
Kind regards,

50

MP566-II Tube microphone preamplifier with HPF / Re: Possible ICs fried MP566-II

« Last post by JPK on May 19, 2026, 03:58:57 PM »

VO to V- 0.817 volts
Problem here: you have no negative -16V rail.
Check again after unpluging the U5 module.
Check if R53 is OK (1 ohm).