1151

TS500 Tape Simulator / Re: VU meter problem

« on: April 17, 2021, 09:36:43 AM »

Check value and solder joints of R49 and C55. These components define the time constant of the meter.

1152

TS500 Tape Simulator / Re: TS500 EQ shape

« on: April 17, 2021, 09:34:18 AM »

Yes good finding.
Check the values of C1 (470pF marked 471), C2 (470pF), C54 (47pF marked 470), C64 (47 pF), C65 (47pF).

1153

EQP501 Passive Equalizer / Re: alternative opamps

« on: April 16, 2021, 11:09:12 AM »

A damaged Q1 could not put the +16V down.
Remove the DOA and check the +16V again.
If not the DOA, check the diode D1 (can be done in circuit).

1154

TS500 Tape Simulator / Re: Heavy Overtones/Intermodulation

« on: April 16, 2021, 11:00:43 AM »

You could try to "listen" to the sound you get from TP1, TP2, TP3, TP4, TP5, TP6, TP7 by connecting these points to an input of your monitoring.
Hearing where the distortion starts will give us an indication of where to look for.

1155

TS500 Tape Simulator / Re: TS500 EQ shape

« on: April 16, 2021, 08:57:16 AM »

The difference is big in the high frequencies so you could try with a 5kHz sine at the input and check the level at the different TP's with a DMM.

1156

Discussions about the products / Re: SK25 vs SK99

« on: April 15, 2021, 06:58:20 PM »

Yes possible.

what op-amps will work in the 5176?

Most op-amps will.

1157

EQP501 Passive Equalizer / Re: alternative opamps

« on: April 15, 2021, 06:56:16 PM »

Probably yes, as long as they do not output too much DC offset.
Check the DC volts on TP2. If it stays lower that a few millivolts then it's OK.

1158

TS500 Tape Simulator / Re: TS500 EQ shape

« on: April 15, 2021, 06:45:07 PM »

If you could compare the 2 signals on TP1, TP2, TP3, TP4, TP5, TP6 it would give us a clue about the stage where the issue starts.

1159

TS500 Tape Simulator / Re: types of OPA2134

« on: April 14, 2021, 10:32:20 AM »

1- Yes you can use Texas 2134. I am sure you won't hear a difference.
2- Bipolar transistors are all good or all dead. If it works, don't fix it.

1160

TS500 Tape Simulator / Re: Testing The Unit For Correct VAC

« on: April 13, 2021, 09:00:10 AM »

I think you are OK.
The values depend on the potentiometers precision and on your DMM:
Resolution, precision, true RMS or not, maximum frequency.

1161

TS500 Tape Simulator / Re: Testing The Unit For Correct VAC

« on: April 12, 2021, 09:24:05 AM »

It is 0.4, not 0.04 VAC (the decimal point was missing in my message).

This is measured by attaching my DMM to the output XLR connector on my chasis?

Yes DMM connected between pins 2&3 of the output XLR.

Also, what do you mean by "in Bypass"?

Bottom switch on OFF (compressor bypassed).

2) Am I using TP2 and TP0 for testing the VAC for all the test conditions?

The test points TP2/0V are used for the unit setup as described in the setup guide PDF.
The measurements described here are done on the output XLR only.

1162

MP573 Microphone preamplifier / Re: Replacement 2 colour LED

« on: April 12, 2021, 09:13:54 AM »

L-937EGW

1163

MP573 Microphone preamplifier / Re: Blown thermistor

« on: April 12, 2021, 09:12:24 AM »

MF-R030
PFRA.030

1164

MP512 Microphone preamplifier / Re: Can I run a 1731 op amp in a MP5.12

« on: April 12, 2021, 09:04:42 AM »

Yes it will work.

1165

MP573 Microphone preamplifier / Re: Preamp works only when JMP3 jumper is on

« on: April 08, 2021, 11:09:08 AM »

I never blow any, simply by removing my shoes when I handle them. It keeps the body at ground level.
Some careless vendors may supply already damaged devices. I have had several. The ones in our kits are 99.999% OK.

1166

MP573 Microphone preamplifier / Re: Paper clip jumper position when NO DI board

« on: April 08, 2021, 11:02:20 AM »

 if it goes across the first two pins (at the card edge end as in the picture)

Yes correct

1167

MP573 Microphone preamplifier / Re: Led pb and slight noise at high gain

« on: April 07, 2021, 11:27:54 AM »

With the values shown for G to L, you shouldn't get any output!
Did you connect the output transformer when measuring?

1168

TS500 Tape Simulator / Re: Heavy Overtones/Intermodulation

« on: April 07, 2021, 11:21:35 AM »

This is what the distortion looks like on a bypassed working unit, with a 1kHz sine, 1Vrms signal on input.
It is normal that some distortion remains in bypass because the signal still goes through the in and out transformers and the output amp stage.

1169

EQ573 Equaliser / Re: EQ573-II - High band bypass issue

« on: April 07, 2021, 09:51:42 AM »

There is a big wide bell increase in the 4-5k area.

Check that you didn't rverse one of the resistor networks on the back of the switch PCB.

In such a case, do not try to unsolder it, there is a risk of breaking a via. Cut the pins and replace by a new one.
Look for solder bridges on this PCB. Check the solder joints on R15, R16 and SW3.

The SW5 Low-pass switch on the one of the modules are a bit flakey.

You could simply replace it. Same remark as above, do not try to unsolder it. Split it into pieces with cutting pliers until you can extract the pins one by one.

1170

MP573 Microphone preamplifier / Re: Led pb and slight noise at high gain

« on: April 07, 2021, 09:39:50 AM »

How far is the pre from the lunchbox PSU?
The input transformer of the MP573 is sensitive to radiated noise. Make sure there is no power device too close.

1171

CP5176 FET compressor / Re: 1176: Click when bypass

« on: April 07, 2021, 09:19:47 AM »

The clicks may also be induced by the voltage spikes in the relay coil.
Check the solder joints on D1, C19, C20, SW2.
Check that D1 is OK. 
You can also try to replace C19 & C20 and maybe SW2.

1172

LA502 Optical Compressor / Re: Hi! i just completed my 502 and everything seems to be working(powers on

« on: April 07, 2021, 09:07:27 AM »

Redo the setup guide step #5 but do the voltage measurement across R17 instead of the output.
Also you can try to use a lower than 1kHz frequency, like 100Hz, because some voltmeters cannot go very high in frequency.

1173

MP566 Tube microphone preamplifier / Re: GND Pin

« on: April 07, 2021, 08:59:10 AM »

Yes is this case GND = 0V.
If you see nothing on the ohmmeter, this is good news! It means the meter doesn't see a resistance between the power rail and the 0V which also means there is no short-circuit.

1174

MP566 Tube microphone preamplifier / Re: Tube works, but no output voltage.

« on: April 07, 2021, 08:55:53 AM »

It could be a damaged Q1 (2N7000).
This device is sensitive to static electricity and must be handled with your body grounded. Generally removing your shoes is enough.

1175

CP5176 FET compressor / Re: 1176: Click when bypass

« on: March 29, 2021, 10:00:52 AM »

The clics often come from a DC voltage added to the signal.
The DC voltage cannot come from the CP5176 because the circuit is isolated between 2 transformers.
Try to disconnect the input of the compressor and check if you still get the clicks.
In such a case the issue may come from another equipment place before the compressor.