1

LA502 Optical Compressor / Re: LA502 - Only 12V output during Setup Step 5

« on: January 26, 2024, 09:34:25 PM »

I’m not sure if my capi rack limits output or what but direct on the module pins 2 and 4 give me the correct voltages. I just took my previously built la502 and it had the same exact scenario (I had calibrated it with a different lunchbox). Anyways it probably worked the whole time and I apologize for wasting your time!

2

LA502 Optical Compressor / Re: LA502 - Only 12V output during Setup Step 5

« on: January 25, 2024, 09:07:20 PM »

I’m getting 14.33 at tp1 vac
I’m getting 27.5vac across r17

It sounds like it must be the relay then?

3

LA502 Optical Compressor / Re: LA502 - Only 12V output during Setup Step 5

« on: January 24, 2024, 07:08:22 PM »

Desoldered it. 
1-3 - 9.17
6-8 - 9.3
9-12 - 11.33
13-16 - 11.42

Let me know if I should check anything else. 

4

LA502 Optical Compressor / Re: LA502 - Only 12V output during Setup Step 5

« on: January 24, 2024, 06:38:37 PM »

22ohms between pins 2 and 4. R17 is the 1 watt large resistor and is brown black black brown brown. 

To confirm, I should desolder the output transformer and test the pins?

Thanks for your help you’re the best!

5

LA502 Optical Compressor / Re: LA502 - Only 12V output during Setup Step 5

« on: January 24, 2024, 12:57:22 AM »

One more note, I followed all the steps in the troubleshooting guide and got the expected values but it still won’t go over 12v: https://www.soundskulptor.com/forum/index.php?topic=19.0


R2=0.7
R5 = 0.49
Tp1 = 13/14V (something like that)

Since its in circuit I got the in-circuit values (5ohm etc).

thanks again!

6

LA502 Optical Compressor / LA502 - Only 12V output during Setup Step 5

« on: January 24, 2024, 12:32:53 AM »

Trying to setup my newly built LA502 and getting stuck on Step 5 - 
I just finished building a LA502 (I've built about 15 500 series projects so have a little bit of experience). When I was doing the setup, I verified I'm getting 16V and -16V, and I'm getting 1V exact VAC when bypassed. When I flip the switch to in, the range of the gain is about 0.3V to ~12V. I cannot get it to go over 20V per the instructions and am stuck.

I've re-flowed every joint, ensured there are no bridges, and validated that the gain increases after I add a single OPA2134 1 by 1 in each of the 4 slots.

Any suggestions on where to troubleshoot to see why its not able to get over 20V? 

One other note, parts list still shows P5 as part number 502/5K vs 103/10K (pictures/instructions are correct).

Step 5 instructions:
Set the Bypass switch to IN. Increase the GAIN pot and check that you can see the voltage on output increase up to 20VAC at least. Adjust the gain pot to get 15VAC Now turn the PEAK pot clockwise and check that it makes the output voltage go down to 1VAC or less.

7

CP4500 Stereo Bus Compressor / Re: No LED or Meter Light

« on: January 22, 2022, 08:41:16 PM »

LED Fixed. The issue was that the Meter LED wires were backwards (I misread/misunderstood the picture). All good now thank you!

8

CP4500 Stereo Bus Compressor / Re: No LED or Meter Light

« on: January 22, 2022, 07:39:04 PM »

I performed all the tests for PCB-A from "In case your CP4500 doesn't work as expected". everything works there, and here are my values for reference. The meter doesn't move during any of the tests, but I know the meter works because I tested it with a small voltage and the needle moves. I'm wondering if there is something I can test on PCB-FRONT?

Mix = 100%
Ratio = 10
Attack = 0.1
Release =1.2
IN button pressed
HF lift, 100Hz, 50Hz buttons released
Negative meter probe on 0V


V+ =+15 to +16VDC, -> 16.0
V-  =-15 to -16VDC), -> -16.22
+12V = +11.1 to +12.9VDC, -> 11.95
-12V  = -11.1 to -12.9VDC -> -11.8







Step 1 conditions plus:
Input signal = 0V
Threshold on +15
Makeup on 0


TP1, TP2, TP3, TP4, TP11, TP12 = 0VDC -> all 0






Step 1 conditions plus:
Input signal = 0V
Threshold on +15
Rotate Makeup from 0 to +20


TP12 goes from 0 to -2.3VDC -> 0 to -2.35V







Input signal = 0V
Makeup on 0
Rotate Threshold from -15 to +15

TP13 goes from -1.8V to +2.8VDC -> 1.81 to 2.83




Input signal = 3VAC
(measured between output XLR pins 2&3
with compressor bypassed)
Makeup on 0
Threshold goes from +15 to -15




TP4 goes from 0.060VAC to 0.190VAC .06 -> .186
TP5 goes from +0.35VDC to a negative value -> .33V to -1.2
TP11 goes from 0VDC to -3.5VDC -> 0 to -3.53
TP12 goes from 0VDC to +3.5VDC -> 0 to 3.53






input signal = 3VAC
Threshold on +15
Makeup on 0


Signal level (VAC) on
TP1=1.5VAC, -> 1.48
TP2=1.5VAC, -> 1.58
TP3=1.5VAC, -> 1.48
TP4=0.06VAC, -> .06
DC voltage (VDC) on
pin 1 of U6 (white dot) = 0V -> 0






input signal = 3VAC
Threshold on -15
Makeup on +20




Signal level (VAC) on
TP1=1.5VAC, -> 1.488
TP2=0.4VAC, -> .438
TP3=1.5VAC, -> 1.488
TP4=0.2VAC -> .186
DC voltage (VDC) on
TP11=-3.5VDC, -> -.352
TP12=+1.2VDC, -> 1.185
TP13=+1.7VDC -> 1.71

9

CP4500 Stereo Bus Compressor / Re: No LED or Meter Light

« on: January 21, 2022, 10:00:18 PM »

I didn't remove any other components, that was only to test the LED. 

The vias are connected from top to bottom (tested with DMM). should I solder the LED back in?

10

CP4500 Stereo Bus Compressor / Re: No LED or Meter Light

« on: January 21, 2022, 04:19:49 PM »

LED lights up and there is no short. 

Please see this link with pictures (3) of the circuit as well as the LED working/no Short with the DMM.

thanks for your help!

https://imgur.com/a/BRVc3ea 

11

CP4500 Stereo Bus Compressor / Re: No LED or Meter Light

« on: January 20, 2022, 06:47:34 PM »

Additional Details:

- Check the meter (unplugged): 600 ohms between the large terminals, infinite resistance between any 2 other terminals. 
- - - 582 ohms
- Check the relay coil (in circuit), 2800 ohms across D19 (check D19 direction). 
- - - 2900 ohms
- Check R104 value (in circuit).
- - - 220 ohms
- check pin 2 shorts to LED Long.
- - - It is shorted between that 2nd pin and the LED Long (d3)
- Check CN2A shorts
- - - Not shorted

I verified all the diodes face the right way, solder joints are solid, etc. Thanks again!

12

CP4500 Stereo Bus Compressor / No LED or Meter Light

« on: January 20, 2022, 05:34:36 PM »

The LED light and VU light are not illuminating.

i have all the right values for -12V, V-, V+, and +12V. Additionally I see 600OHM (roughly) across the VU outside leads. I verified the LED works with my DMM.

I checked for any shorts along CN2B based on the other thread I was reading. Can you help me with what else I need to test?

Thanks!