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Messages - JPK

Pages: [1] 2 3 ... 43
1
First Aid / Re: MP512 Outputs random static
« on: July 19, 2024, 08:34:29 AM »
I don't believe the tranformer can become faulty. Try reflowing the solders.
Reinsert the DOA to make sure the connections are good.
Try tapping on the large caps to check if it increases the noise.
Also do the same on the pad potentiometer.

2
MP566 Tube microphone preamplifier / Re: C4 and R51 specs
« on: July 17, 2024, 11:20:40 AM »
No problem, you can move forward.
The 315V is still well above our B+  which is at 225V.
If the colour code on the resistor is correct (violet, green, black, silver) then the resisor is correct within 1%. The typical ohmmeters are generally not very acurate for the extreme values (very small or very large). Also, it adds the resistance of the leads, and connections to the resistor value.

3
CP4500 Stereo Bus Compressor / Re: Meter Light not working
« on: July 09, 2024, 08:39:49 AM »
Be carefull to ground your body when handling the 2N7000 (removing your shoes does the trick). It is very sensitive to static electricity.

4
CP4500 Stereo Bus Compressor / Re: Meter Light not working
« on: July 08, 2024, 10:58:50 AM »
You should replace these components.
The diode protects the meter against too larger voltages: BZX55C2V4-TAP
The transistor prevents the meter moving when it is bypassed: 2N7000
Two very common and cheap components.

5
CP4500 Stereo Bus Compressor / Re: Meter Light not working
« on: July 07, 2024, 09:27:37 AM »
Try removing Q1 and D18.

6
MU524 Vari-Mu Tube Compressor / Re: AudioPath Test Question
« on: July 03, 2024, 04:38:29 PM »
👍

7
MU524 Vari-Mu Tube Compressor / Re: AudioPath Test Question
« on: July 02, 2024, 03:39:20 PM »
The upper side of R8 should be at 46 Volts.
It is only connected to R6, R7 and C7.
Check these components. There must be something wrong here, like a solder bridge of a bad solder joint.

8
MP573 Microphone preamplifier / Re: Bias Adjust
« on: July 02, 2024, 03:30:21 PM »
I ususally wait 5 mn before adjusting.

9
MP573 Microphone preamplifier / Re: Bias Adjust
« on: July 01, 2024, 03:20:56 PM »
It is normal for the voltage to drop a little, around 100mV, as the unit warms up but it should stop when it reaches its equilibrium temperature.

10
LA502 Optical Compressor / Re: LA502 - PCB 1.2->1.3 C5 47p cap
« on: June 27, 2024, 05:53:11 PM »
No, not necessary.
This cap ensures better Common Mode Rejection Ratio (CMRR) in case the 2 caps differ in value.

11
MU524 Vari-Mu Tube Compressor / Re: AudioPath Test Question
« on: June 23, 2024, 03:36:56 PM »
What is the DC voltage on each side of R8, against 0V ?

12
CP4500 Stereo Bus Compressor / Re: Meter Light not working
« on: June 23, 2024, 03:34:44 PM »
- Check the solder joints of CN4 and connector to wires connections.
- Check the solder joints of R100 and trimmer T4. Check the ohmic value of T4.
- Try removing Q1.

13
AB528 Microphone preamplifier / Re: Preampli AB528
« on: June 22, 2024, 03:51:06 PM »
Est-ce que vous entendez le clic du relai quand vous passez sur 300 ?

et aussi un genre de léger bruit d'oscillation
Vérifiez les valeurs et soudures des condensateurs, en particulier C2, C3, C4, C5, C7, C8, C11, C14, C16.

14
CP4500 Stereo Bus Compressor / Re: Meter Light not working
« on: June 22, 2024, 03:44:06 PM »
Does the needle move when you take the measurement?

15
MU524 Vari-Mu Tube Compressor / Re: Match des potentiomètres et bruit sur second MU524
« on: June 22, 2024, 03:42:31 PM »
Pouvez-vous relever les tensions indiquées ici ?
https://www.soundskulptor.com/forum/index.php?topic=347.msg1907#msg1907

16
MU524 Vari-Mu Tube Compressor / Re: AudioPath Test Question
« on: June 19, 2024, 11:12:16 AM »
TP1 290 mV VDC
TP2 203 mV VDC
These pins should be above 30VDC, against 0V.
Check the solder joints on R8.

17
CP4500 Stereo Bus Compressor / Re: Meter Light not working
« on: June 19, 2024, 10:57:39 AM »
Yes, after disconnecting the meter connector.

18
MU524 Vari-Mu Tube Compressor / Re: AudioPath Test Question
« on: June 17, 2024, 11:58:32 AM »
What is the DC voltage, against 0V, on the test pin B+.
It should be around 45V.

19
MP573 Microphone preamplifier / Re: MP573 general power check and deviating DC voltages
« on: June 17, 2024, 11:53:59 AM »
👍

20
CP4500 Stereo Bus Compressor / Re: Meter Light not working
« on: June 17, 2024, 11:52:10 AM »
First check that the meter is working by measuring its internal resistance (connector unplugged). This should move the needle. Around 600 ohms.

21
MU524 Vari-Mu Tube Compressor / Re: AudioPath Test Question
« on: June 13, 2024, 10:53:11 AM »
What AC value do you read when directly connected to the source at 0.0dB, without the MU524 connected.

22
AB528 Microphone preamplifier / In case your AB528 doesn't work as expected
« on: June 12, 2024, 05:15:00 PM »
Check the usual suspects:
  • Check you didn't leave the polarity switch on the center position (=mute),
  • Forgotten solder joint,
  • Bad solder joint (reflow suspicious joints),
  • Reversed components (electrolytics, diodes, transistors, IC's). In case of IC's, probably destroyed, better replace,
  • Flipped IC's or transistors,
  • Trim all the component leads and test pins as short as possible. Nothing must touch the chassis plate.

Check the DC voltages:
First check the supply voltages as described in the setup guide.
Next, without any input signal, connect the voltmeter black probe to the 0V test pin and note the DC voltages you get at the points shown on the attached picture. Compare with the expected results (more or less 10%).


23
AB528 Microphone preamplifier / Re: Preampli AB528
« on: June 12, 2024, 04:08:10 PM »
Le problème se situe dans l'étage de sortie.
Vérifiez valeur, direction et soudures des composants Q3, Q4, Q5, Q6, R22...R29, C13...C18.

J'ai ajouté un topic pour les tests :
https://www.soundskulptor.com/forum/index.php?topic=498.msg2966#msg2966

24
MP566 Tube microphone preamplifier / Re: Solder bridge on C9 and C10?
« on: June 10, 2024, 12:18:19 PM »
or is it harmless, and better to leave it this way?
Yes harmless. These pads are already connected together. They are only there to allow the use of capacitors having a different distance between pins.

25
MU524 Vari-Mu Tube Compressor / Re: AudioPath Test Question
« on: June 10, 2024, 11:10:39 AM »
No matter what I change in my daw I can't get it close to 1.0 vac.
Do you mean when bypassed?
If true, it is either a connection issue: check your connections from your audio source,
or you have a bad solder joint on the relay.
Do you hear the relay clicking when you move the bypass switch?

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