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Messages - JPK

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1
the conrad relay is the correct one despite their photo which does not correspond

Is this a problem?
No.

3
EQ573 Equaliser / Re: EQ573-II noisy in pre mode
« on: February 21, 2024, 03:58:58 PM »
Does the signal/noise get better if you increase the input level of the EQ with the gain rotary switch on the preamp?
Try maximizing the level on the gain switch (and reducing the level with the +/-10dB pot).

4
MP599 Microphone preamplifier / Re: MP599 preamp not working
« on: February 21, 2024, 03:52:11 PM »
Yes to both.

5
I accidentally touched the corner of RLY1 with the iron
This is most likely the cause of the failure.

You will need to remove the input transformer to change the relay. follow the guide here.
The relays are:
AZ850-24 or TQ2-24V or EA2-24NJ.

6
MP599 Microphone preamplifier / Re: MP599 preamp not working
« on: February 20, 2024, 10:07:02 AM »
both the diodes are soldered in the wrong direction
This is the issue for sure. The diodes may have survived.

Will 1N914 Signal diode work ?
Yes.

When I place the final plate, it touches the top of Capacitor C9, is that okay ?
This is not a problem.

7
It could be one of the relays.
Is it the same in 300, 1200, line?
Is it the same from the DI input?

8
Try removing the jumper JMP1 and listen if it is still there. This would show that it doesn't come from the side chain.
Try tapping various components (tube, electrolytics, pots) with a pen to hear if it increases the noise.
Is the noise level dependent on the input pot, the output pot?

9
MP566 Tube microphone preamplifier / Re: MP566 not working
« on: February 19, 2024, 05:58:23 PM »
1 -14,49 V
7  12,55 V
8  2,850 V

With these values, the outpout pin 1 should be positive. 
If the values are correct then U4 seems to be dead again.

10
DI503J Triple DI and Re-Amp / Re: Crunchy sounding Preamp pot
« on: February 19, 2024, 05:48:19 PM »
👍

11
MP599 Microphone preamplifier / Re: MP599 preamp not working
« on: February 19, 2024, 05:47:21 PM »
Check that you inserted Q2 in the right holes (position A).
Can you measure the signal from the DI input on the test pin TP4 (against 0V), measured with our AC voltmeter?

12
All this is correct.
Did you check the ususal suspects ?

13
The unit was supposed to be ON for the measurements.
Can you measure the DC voltages, against 0V, on :
- U1 pin 14 (0VDC),
- U1 pin 7 (0VDC),
- U1 pin 8 (0VDC),
- Q2 collector (the pin closest to U1) (? 4 VDC),
- Q4 collector (the pin closest to C6) (? 4 VDC).

14
Can you do the same test on the input transformer primary, between pins 2 & 5 ?

15
Do I need a signal generator or function generator
Yes. Or you can use your DAW and loop a sine signal or use a sine generator pluggin.

and an oscilloscope for this test?
A scope makes things easier but your DMM can do the job.

16
You can increase the input voltage to 4VAC to make measurements easier. You will need to remove the chassis plate.
Check that you receive the input signal voltage on the secondary of T1 between pins 7 & 10 (? 0.9 VAC)
Check that you receive the input signal voltage on the primary of T2 between pins 2 & 5 (? 0.1 VAC)
Check that you receive the input signal voltage on the secondary of T2 between pins 7 & 10 (? 0.19 VAC)
Check that you receive the input signal voltage on TP1 against 0V (? 4.7 VAC)
You may keep the output transformer disconnected for all this test.
Check that 

17
MP566 Tube microphone preamplifier / Re: MP566 not working
« on: February 13, 2024, 03:32:13 PM »
Can you measure the DC voltages on the 8 pins of U4?
I mean all the 8 pins.

18
The voltages are spot on, so it is not a supply issue.
Now Try to follow the signal, before and after the disappearance of sound to find out at which stage it breaks.

Send a good constant sine signal on input, like 0.5VAC measured between pins 2&3 of the input XLR.
Connect the voltmeter black probe to TP2 and trace the signal on:
  • Input transformer pin 7: 0.9VAC,
  • TP1: 4.8VAC (Gain=40, TRIM=Min),
  • output transformer yellow wire: 8.4VAC (Gain=40, TRIM=Min).


19
Can you please recheck the DC voltages A to L once the sound is gone?

20
MP566 Tube microphone preamplifier / Re: P1/P2 100K LogB Pots
« on: February 12, 2024, 11:14:56 AM »
Please contact me here.

21
MP566 Tube microphone preamplifier / Re: MP566 not working
« on: February 12, 2024, 11:13:49 AM »
black Probe on 0V + red probe on U4 pin 1 = -14,49V
It should be positive.
Can you measure the DC voltages on the 8 pins of U4?


22
MU524 Vari-Mu Tube Compressor / Re: Light Hiss/Noise
« on: February 12, 2024, 11:07:27 AM »
Can you measure the noise voltage at the output with the input pot at min and output pot at max?
Should be around 1mVAC.
If higher, try moving the unit to a different slot, further away for the PSU?

23
CP5176 FET compressor / Re: Different input level on stereo pair
« on: February 12, 2024, 10:45:52 AM »
👍

24
MU524 Vari-Mu Tube Compressor / Re: MU 524
« on: February 10, 2024, 04:03:36 PM »
👍

25
For drums, an obvious choice would be the MP573 followed by a pad500 in order to be able to drive it into saturation while controlling the output.
The tube MP566 is also interresting for the tube saturation.

How close is running line signals through a comp
A compressor is designed for line input signals, therefore very difficult to saturate.

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