Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Messages - JPK

Pages: 1 ... 37 38 [39] 40 41
951
MP573 Microphone preamplifier / Re: 100 Hz Hum And No Input
« on: February 08, 2021, 07:24:00 PM »
Is it still there with the jumper JMP3 in?

952
CP4500 Stereo Bus Compressor / Re: CP4500 went dark during setup part 6
« on: February 08, 2021, 07:22:18 PM »

Quote
What if i remove the resistor, and try to insert a new (temporary) LED again
Any LED will do, the specs are very tolerant.

You got 2 LEDs burning in a row, this shows another issue.


953
CP4500 Stereo Bus Compressor / Re: CP4500 went dark during setup part 6
« on: February 08, 2021, 06:52:18 PM »
This looks plain normal!
Nothing happens if you shake the wires to the meter a little?
I just cannot understand how the green LED may have burnt. And why the needle went to 20.
I suspected an intermittent short circuit inside the meter.

954
CP4500 Stereo Bus Compressor / Re: CP4500 went dark during setup part 6
« on: February 08, 2021, 04:01:28 PM »

What DC voltage across the 1k5?
What DC voltage across the meter small terminals?
What DC voltage across the relay (taken across D19)?
What DC voltage across R104?
Does the meter lights up?









955
CP4500 Stereo Bus Compressor / Re: CP4500 went dark during setup part 6
« on: February 08, 2021, 02:39:44 PM »

Quote
Is this the correct way in your eyes?
Yes you are correct.


Quote
If i choose to increase sensitivity to 20M, i do not get a reeading between probes anymore, but now i get a reading between VU+ and VU- pins on CN2a, without PCBc connected on 0,25
This is not a short circuit.


Can you temporarily replace the LED by a resistor of 1 to 1.5 k ?
And check if you can hear the relay clicking when you activate the compressor.

956
CP4500 Stereo Bus Compressor / Re: CP4500 went dark during setup part 6
« on: February 08, 2021, 12:19:23 PM »

Quote
569 Ohm, on large terminals  and only "1" (infinite, right?) between the small ones
You must also check between the small and large terminals, in case there is a short circuit inside the meter.






957
TS500 Tape Simulator / Re: Ts500 not working
« on: February 08, 2021, 12:14:48 PM »

Quote
0v and v - = 0.8  v :(
Can you check V- in the rack?


Quote
0v and Tp7 - 15.93 k-ohms
0v and Tp6 :
when off - ascending values from 110 k-ohms up until 130 but then i turned it off
when mute - 47.3 k-ohms
when on - 1.6 k-ohms
I was asking for volts, not ohms.


958
MP573 Microphone preamplifier / Re: 100 Hz Hum And No Input
« on: February 08, 2021, 11:15:38 AM »
Try replacing the 2N7000 on the DI board.
This component is very sensitive to static electricity and should be handled with your body grounded (removing your shoes).

959
CP4500 Stereo Bus Compressor / Re: burned led
« on: February 08, 2021, 11:08:35 AM »
You can temporarily replace the led by a short.
Was the meter shorted from the start?
Did you repair the meter by opening the back or the front?

960
CP4500 Stereo Bus Compressor / Re: CP4500 went dark during setup part 6
« on: February 08, 2021, 11:07:40 AM »
You have too much current in the LED. The current is limited by R104, RLY1, Meter LED.
- Keep the IC's removed until this is sorted out.
- Check the meter: 600 ohms between the large terminals, infinite resistance between any other terminals.
- Check the relay coil, 2800 ohms across D19.
- Look for a short circuit between the CN2 Vu- pin (second down-left)and any other close pin.

961
Discussions about the products / Re: SK25 vs SK99
« on: February 07, 2021, 10:24:20 AM »
You are correct.
The SK25 is best suited to high impedance source like high ratio input transformer. It is a little darker than the SK99 and it is nicer when overdriven. So it is close to the API2520.
The SK99 is best suited to lower impedance source like low or medium ratio input transformer. It is also faster than the SK25, so more open and more detailed. So closer to the 990.
Actually both share the same design and the difference is in the value of 3 resistors. The kits contain both sets so you can experiment.

962
CP4500 Stereo Bus Compressor / Re: CP4500 went dark during setup part 6
« on: February 06, 2021, 08:30:59 AM »
Right!

963
CP4500 Stereo Bus Compressor / Re: CP4500 went dark during setup part 6
« on: February 05, 2021, 05:21:50 PM »
The green LED is needed to power up the unit so you need to replace it or short it temporarily.
As you can see on the schematic page 3, the on/off switch activates the bypass relay via the green LED, the meter LEDs and R104.
You can check if there is unusual current through R104 (suspicion due to the LED turning red) by measuring the voltage across it: 1.6V

964
TS500 Tape Simulator / Re: Ts500 not working
« on: February 05, 2021, 03:54:42 PM »
Remove U12.
Check R50 & R51 in circuit (1R). They should look almost like shorts.
Check R41 in circuit (33R). If open circuit, replace.
Check V+ and V- by powering very shortly each time (1 or 2 seconds).

Check the DC volts on TP7. Should be around -200mV.
Check the DC volts on TP6. Should be at 0V.
Reflow any suspicious joint.
Brush the PCB to remove any unwanted solder bits.

965
MP566 Tube microphone preamplifier / Output transformer check
« on: February 04, 2021, 05:49:31 PM »
This is how you can check the output transformer by measuring the coils DC resistances
The POL switch must be in the center position.

7  8  9  10 11 12
o  o  o  o  o  o


o  o  o  o  o o
6  5  4  3  2 1

pin1-pin3 : 106 ?
pin4-pin6 : 101 ?
pin9-pin11 : 102 ?

966
CP4500 Stereo Bus Compressor / Re: CP4500 went dark during setup part 6
« on: February 04, 2021, 03:44:34 PM »
Look at the attached pic that shows the pins interconnect and connections.
Check that you get the correct signals on each pin. You might have destroyed some vias when removing the connector.

967
CP4500 Stereo Bus Compressor / Re: TP 12 reads 14.7 DC
« on: February 04, 2021, 03:29:29 PM »
What DC voltage do you get on TP11?
Is the meter needle resting at 0?
Is this voltage changing when you move the Mix pot?
Check the solder joints on pot P2, on connectors CN2A and CN2B, resistors R90 to R94, IC U22.

968
CP4500 Stereo Bus Compressor / Re: CP4500 went dark during setup part 6
« on: February 03, 2021, 04:13:49 PM »
Remove all the IC's for their safety.
First things to check :
https://www.soundskulptor.com/forum/index.php?topic=11.msg11#msg11

Reversed D19, D20 diodes?
Reversed relays?
R104, R105 value?
Solder bridges on CN2a/CN2b connectors.

Check the LED with a DMM

969
MP566 Tube microphone preamplifier / Re: Hum at 60hz
« on: February 03, 2021, 09:13:07 AM »
The frequency is around 70Hz so it is probably not mains induced.
Try keeping the unit ventilated to find out if it is linked to the temperature.

970
MP566 Tube microphone preamplifier / Re: Hum at 60hz
« on: February 01, 2021, 05:36:32 PM »
Yes, this would allow us to find out if the noise comes from the MP566  itself or from the housing supply.

971
MP566 Tube microphone preamplifier / Re: Hum at 60hz
« on: February 01, 2021, 04:02:29 PM »
Could the hum be induced by a power device in proximity?
The input transformer even if shielded with mu-metal can be sensitive to radiated noise.
Is your lunchbox powered by a linear PSU (with a mains transformer)?


972
CP4500 Stereo Bus Compressor / Re: 2nd card/ch T2 trim not close
« on: February 01, 2021, 03:57:50 PM »
On channel 2, the input signal just after unbalancing is on TP6
and the output signal just before re-balancing is on TP7.
You can see this clearly on the schematic.

973
CP4500 Stereo Bus Compressor / Re: How can I test the Side Chain HF Lift?
« on: January 31, 2021, 06:31:02 PM »
Send a high frequency sine signal like 10kHz to the compressor.
Dial in some compression to reduce the signal level.
Press the HF lift switch.
The output signal level goes down because the side chain compresses the high frequencies more.

974
XT500 Lunchbox connector extender / Extender pins description
« on: January 31, 2021, 06:26:10 PM »
Pin   Name                                          Description
1Chassis groundLunchbox chassis
2Output +4dB HotOutput XLR pin 2
3Output -2dB HotLow level output (not used)
4Output +4dB ColdOutput XLR pin3
5Analog groundInput and output XLR pin 1
6Stereo linkConnects the side chains of 2 adjacent compressors
7Input -2dB coldLow level input cold (not used)
8Input +4dB coldInput XLR pin 3
9Input -2dB HotLow level input hot (not used)
10Input +4dB HotInput XLR pin 2
11Gain AdjustBuss feed on Radial lunchboxes
12+16VDCPositive power supply
13Power groundConnected to the Analog ground in the lunchbox
14-16VDCNegative power supply
15+48VDC PhantomMicrophone phantom power supply

975
CP4500 Stereo Bus Compressor / Re: No Signal On 2nd Channel of the CP4500
« on: January 30, 2021, 12:12:56 PM »
But you do get 3VAC on the output when the compressor is Off, do you?

I checked out TP7, TP8 and TP9 as you suggested, and they all checked out around 1.5VAC...
Do you confirm this?
If you do, then the issue can only be with U17.
If you get the signal on U17 pin4  but nothing on pin1 and pin8 then U17 is bad.

Pages: 1 ... 37 38 [39] 40 41