81

MU524 Vari-Mu Tube Compressor / Re: TR4 will only go down to 5V

« Last post by JPK on April 24, 2025, 07:13:37 PM »

You are on step 8, right?
What is the DC voltage on TP6 whenTR4 is all the way CCW.
Same question on U1 pin1 ?
Same question on U4 pin6 ?

82

MU524 Vari-Mu Tube Compressor / Re: something wrong with my build

« Last post by JPK on April 24, 2025, 07:05:50 PM »

83

MU524 Vari-Mu Tube Compressor / Tube ECC189 de remplacement

« Last post by Mateo_K on April 24, 2025, 01:40:27 AM »

Bonjour Jean-Pierre,

Je me demandais si vous auriez un vendeur à conseiller pour l'achat de tubes de rechange pour le MU524.
J'ai vu que vint'elec en propose,
Qu'en pensez vous ?

Merci beaucoup et bonne journée !

Matéo

84

MU524 Vari-Mu Tube Compressor / TR4 will only go down to 5V

« Last post by carvedinlava@gmail.com on April 21, 2025, 03:19:03 PM »

When setting up TR4 it will only go down to 5v instead of 3v from 6v 

85

MU524 Vari-Mu Tube Compressor / Re: something wrong with my build

« Last post by Mona on April 19, 2025, 11:37:18 AM »

found it. Works like a charm now and sounds amazing. It was a bad soldering at T1 and TR1 was bad. really happy thanks again.

86

MU524 Vari-Mu Tube Compressor / Re: No AC volage from TP1 on

« Last post by JPK on April 11, 2025, 09:54:00 AM »

87

MU524 Vari-Mu Tube Compressor / Re: No AC volage from TP1 on

« Last post by coostor on April 10, 2025, 10:57:38 PM »

U6 had to be replaced with a new one. No voltage came out at the output. 
After replacement everything works perfectly, all measured values are correct.


Thank you for everything,
C.

88

MU524 Vari-Mu Tube Compressor / Re: No AC volage from TP1 on

« Last post by JPK on April 07, 2025, 05:41:23 PM »

Did you check the glowing in the dark? Because it is not very visible in daylight.

Power up the lunchbox: 5,5 V then more to 6.2 V after 10 seconds.
Do you confirm this? Check the solder joints of the tube socket and the header connecting the tube PCB to the main PCB.

89

MU524 Vari-Mu Tube Compressor / Re: No AC volage from TP1 on

« Last post by coostor on April 06, 2025, 08:59:19 PM »

The values, directions and soldering of L1, L2, U6, C30-C33, D9, R38, R39, Q4 are correct.
I have no idea what the problem could be...

90

MU524 Vari-Mu Tube Compressor / Re: No AC volage from TP1 on

« Last post by JPK on April 04, 2025, 10:05:48 AM »

Check value, dirction and solder joints of L1, L2, C30...C33, R38, R39, D9, U6, Q4.
In particular, make sure U6 and Q4 are in the correct direction:
- Pin 1 of U6 towards L2, coil facing T1.
- Writings on Q4 towards R39.