Sound Skulptor forums
Build help and troubleshooting => CP4500 Stereo Bus Compressor => Topic started by: rob@roblanter.com on January 26, 2021, 10:46:53 PM
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Hi,
I don't seem to be getting any signal on channel 2. Channel one seems to be working perfectly, but I do not get any readout on the DMM for channel 2.
What can I do to debug the problem.
Thanks,
Rob
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Mix = 100%, Ratio = 10, Attack = 0.1, Release =1.2, IN button pressed, HF lift, 100Hz, 50Hz buttons released,
Negative meter probe on 0V,
Threshold on +15, Makeup on 0,
input signal = 3VAC,
Follow the signal (VAC) on TP6=1.5VAC, TP7=1.5VAC, TP8=1.5VAC
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Hi JP,
I went back to the other posting "In case your CP4500 doesn't work as expected" and when I measured DC voltage on pin1 on U16 I got .8 at +15 threshold and 209.5 at for -15 threshold. Is it possible that the U16 IC is burnt out?
When I was first testing the unit after my build, I did not know that the IC chips had specific placement. The instructions just say to place the IC chips, and since I am new at this and really am just learning, I did not realize that there were specific chips in specific sockets. Consequently, when I was testing Channel A, some of the chips got really really hot. After I turned the unit off and investigated, I realized that the chips had to be placed in specific locations by looking at the components layout document. I rearranged the chips according to the document and channel A worked perfectly. If some of the chips are burnt out, they could be on the channel B PCB causing the weird readout on U16.
What do you think?
Thanks,
Rob (newbie)....
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Hi,
I checked out TP7, TP8 and TP9 as you suggested, and they all checked out around 1.5VAC...
I went back to the other posting "In case your CP4500 doesn't work as expected" and when I measured DC voltage on pin1 on U16 I got .8 at +15 threshold and 209.5 at for -15 threshold. Is it possible that the U16 IC is burnt out?
When I was first testing the unit after my build, I did not know that the IC chips had specific placement. The instructions just say to place the IC chips, and since I am new at this and really am just learning, I did not realize that there were specific chips in specific sockets. Consequently, when I was testing Channel A, some of the chips got really really hot. After I turned the unit off and investigated, I realized that the chips had to be placed in specific locations by looking at the components layout document. I rearranged the chips according to the document and channel A worked perfectly. If some of the chips are burnt out, they could be on the channel B PCB causing the weird readout on U16.
What do you think?
Thanks,
Rob (newbie)....
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The IC's generally don't like to be placed in the wrong position.
There is a good probability that U11 or U17 or both are dead.
Try swapping them with good ones from the working channel.
I got .8 at +15 threshold and 209.5 at for -15 threshold
Are you speaking in millivolts? If so then the values are correct.
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Hi,
Thanks for getting back to me...I just replaced all the ICs on Channel B with newly bought chips.
I get a reading of 0.000 on the DMM on channel B. I can't get any VAC at all, so I really can't perform the test you suggested in the thread. On Channel A, I can set 3VAC from my DAW, but when I attach my DMM to the output XLR on channel B, I get 0.000VAC.
Thanks,
Rob Lanter
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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.
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Hi JP,
I can confirm 1.5VAC on TP7, TP8. TP9 is .06VAC.
For U17 I get:
pin1 - 2.9VDC
pin 4 - 1.0
pin 8 - 1.1
Thanks,
Rob
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Hi JP,
Good news.. I think.the unit is working perfectly...still need to verify the side chain functionality ratio and release, but so far my test has indicated everything is working...I had some bad solder joints. Re soldered all the IC's and some other points that looked bad and now it all seems to work...thanks for you help.
Rob