Sound Skulptor forums
Build help and troubleshooting => CP4500 Stereo Bus Compressor => Topic started by: forcemusicgroup on April 10, 2022, 06:02:34 AM
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Ive gotten great readings all the way up to step 4 on PCB Board 1 - TP13 does not fluctuate from -1.8v to +2.8v it remains constant while adjusting the make up gain.
The value remains constant at 2.87v
Please advise.
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it remains constant while adjusting the make up gain.
Normal. TP13 should vary with the threshold knob, not the makeup.
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my mistake... the threshold. remains constant. ive emailed close detailed pictures in your email for further review
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(https://i.imgur.com/E4TbdpH.jpg)(https://i.imgur.com/oQveQZr.jpg)(https://i.imgur.com/IqkI7Bt.jpg)(https://i.imgur.com/2U5QOUN.jpg)
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Stopping at Step 5 these are the results
tp4 - 0.0058 to 0.217
tp5 - 0.0 @-15 2.51@+15
tp11 - 0.0@-15
0.0 @+15
tp12 0.0@ -15
0.0@+15
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Conditions of step 4.
Check that you get the THRESHOLD command voltage on R95-left pin. It should go from -12 to +12V when moving THRESHOLD.
If OK, please report the DC volts on all the pins of U21.
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From your photos, I can see that you have misplaced a THAT 1246 in U7. It should be a THAT1646 here.
You probably also have an issue in U11 (I cannot see the ref on the picture).
This may have destroyed the IC's. Check if they are getting hot.
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Yes they are getting Hot. You can smell heat if that makes sense...
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You will need to replace them.
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Conditions of step 4.
Check that you get the THRESHOLD command voltage on R95-left pin. It should go from -12 to +12V when moving THRESHOLD.
If OK, please report the DC volts on all the pins of U21.
r95 pin isnt reading -12 to +12..... more like 4VAC going CCW and CW
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That chips have been replaced as well please advise @JDK
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r95 pin isnt reading -12 to +12..... more like 4VAC going CCW and CW
We are looking for DC volts here. You must set your DMM to DC.
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ok I have it +15 gives me -11.86 vdc
@ -15 gives me +12.03vdc
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U21 pins from top left side down
pin 1 -.007
pin 2 -.007
pin 3 -.007
pin 4 - -16.27
pin 5 - +15.36
pin 6 - +2.884
pin 7 - 0.0
pin 8 - 0.00
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Please advise @jpk
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Check the value and reflow the solder joints of R95 to R99 and U21.
If nothing works, try swapping U21 with another OPA2134 from channel 2.
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Checked the of the resistors. all seem to be what is required. Swapped the OPA chip and got the same result and numbers. Please advise....
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Do do still confirm TP13 doesn't change FROM 2.9V when turning THRESHOLD ?
Check the continuity between R95-right and R96-right.
If OK, you will need to send us your unit for fixing.
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Tp13 does change with threshold is turn... from 1.8vdc to 2.8vdc
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Correction -1.8vdc to 2.8vdc
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Valeurs normales.
Quel est le problème maintenant?
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English?? Plz
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I can't get the levels on the channels to balance... the meter does jump.
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English?? Plz
Sorry!
You need too go again through the voltage tests here (https://www.soundskulptor.com/forum/index.php?topic=3.msg3#msg3).
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All voltage checks are fine at this point. Channel 2 is .5 - 1.5 db off. I've moved the trims and nothing changes.
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TP7 value seems to be extremely high compared to what im supposed to be getting ---------12.15VAC where as its supposed to be 1.5vac
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TP7 at 0 makeup is 1.3vac and @+20 makeup is at 13.12vac
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In which step do you get this result?
TP7 at -20 makeup
I assume you mean @0 MAKEUP.
You need to be more specific in your descriptions or I can't make any deduction.
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Yes at 0 make up those are the values
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You didn't reply to the question:
In which step do you get this result?
Without knowing the context I cannot make any deduction.
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step 1 voltages
v+ 15.2
v- 16.2
-12v 11.5
+12v 11.7
step 2
tp 1,2,3,4,11,12 =0VDC
step 3
tp12 = -2.9vdc
step 4
tp13 @-1.8vdc
@2.9vdc
step 5
tp4 @-15TH =0.21
@+15TH =.058
TP5 @+15TH =.334VDC
@-15TH =-2.221VDC
TP11@+15TH =.012
@-15TH=-3.39
TP12@-15TH=3.4VDC
@+15TH=0
STEP 6
TP1=1.5VAC
TP2=1.439VAC
TP3=1.51VAC
TP4=0.06VAC
DCV = -0.001
STEP 7
TP1=1.5VAC
TP2=0.470VAC
TP3=1.51VAC
TP4=0.217VAC
TP11=-3.39VDC
TP12=1.03VDC
TP13=1.59VDC
CHANNEL 2
-V = 16.21
+V = 14.77
-12V= 11.87VDC
+12 = 12.03
STEP 2 C2
TP6=0
TP7=0
TP8=0
TP9=0
STEP3 C2
TP6=1.5VAC
TP7=1.36VAC
TP8=1.5
TP9=0.06
STEP4 C2
TP6=1.5VAC
TP7=0.4VAC
TP8=1.5VAC
TP9= 0.2VAC
VDC U16 =.058
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step 3
tp12 = -2.9vdc
In step 3 conditions, does the voltage on TP12 go to 0V when Makeup is at 0 ?
Without and with channel 2 installed?
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Yes. 0v with channel 2 installed and without... fluctuating no more than .5 -/+vac moving make up 0 to +15
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Sorry, not understanding:
The voltage measured on TP12 are DC volts and without input signal (step 3).
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With make up @+20 I get -2.384vdc with second channel attached
-2.37vdc without board 2 attached
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What I need to know is:
In step 3 conditions, does the voltage on TP12 go down to 0V when Makeup is at 0 ?
Without and with channel 2 installed?
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Yes
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Channel 2 - step 3
Is TP7 still too low (1.36VAC instead of 1.5VAC) if you remove U17?
Check the resistor value (with power off, U16 removed, Trimmer T2 fully CW) between TP7 and U16 pin 6 : 5k7 ?
Check the resistor value (with power off, U16 removed, Trimmer T2 fully CCW) between TP7 and U16 pin 6 : 4k7 ?
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Will do stand by
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tp7 with u17 removed comes to 1.694 vac
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Check the resistor value (with power off, U16 removed, Trimmer T2 fully CW) between TP7 and U16 pin 6 : 5k7 ? = 5.682k ohm
Check the resistor value (with power off, U16 removed, Trimmer T2 fully CCW) between TP7 and U16 pin 6 : 4k7 ? 4.699 k ohm
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tp7 with u17 removed comes to 1.694 vac
It seems that U17 is bad.
Try replacing it with U7.
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Ok changed. What should I be looking for
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In channel2 step 3, is the level on TP7 back to 1.5VAC instead of 1.36VAC.
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Same. I noticed that when I changed out the chips that the volume changes channels. The 1646 chips are new from
Mouser.
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I noticed that when I changed out the chips that the volume changes channels.
Can you please explain? What change on what channel ?
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Moving and changing the 1646 from ch a to b
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The THAT 1646 must be defective.
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Well I've tried several. And still can't get a match. It's off by 1.7db
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Sorry, I am out of ideas.
Do you want to send it to us for a check? Contact me here (https://www.soundskulptor.com/en/content/6-contact).
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(https://i.imgur.com/wHHEUxV.jpg)