1

MU524 Vari-Mu Tube Compressor / 48 DC volts reading

« on: January 03, 2024, 10:31:41 PM »

Hi I'm building 4 of those and two of them are giving me 33vdc instead of 45-48vdc, what could be the problem? I was able to calibrate it no problem only when it come to adjusting the VU to 6db I can't do it properly.

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CP4500 Stereo Bus Compressor / Re: burned led

« on: February 09, 2021, 03:35:33 PM »

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?

Yes it is fix and ready to calibrate, just going to do it real soon, waiting for the LED.

Here how I did it. I had to basically open the whole thing, taken the black front frame, don't try to unscrew the middle big screw, that is only for adjusting the vu needle. Cutting the securing transparent tape slowly around the meter, open it, then I open the back also since I was not certain where was the short, careful about how the small leds and wire for it, it following a specific path, you will need to put it back the same way. Then I was able to see the short, the cables inside are very fragile, tiny, so I had to do it carefully, I de-soldered the wires and added some heat shrink tubes to protect the connection. put it back together and tested, no more short.

3

Discussions about the products / SK25 vs SK99

« on: February 06, 2021, 07:35:06 PM »

What is the difference sonically between the SK25 and SK99, does the SK25 sound more like the API 2520 and the SK99 more like a Jensen JE990?

4

SK25/SK99 Discrete Op-Amp / Re: getting hot or not

« on: January 14, 2021, 01:12:39 AM »

1. before fixing the soldering



2. after, the opamp does not get hot at all, stay all cool



3. the fix

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CP4500 Stereo Bus Compressor / Re: burned led

« on: January 13, 2021, 09:43:05 PM »

ok i fixed too, it was a short inside the meter itself, pretty delicate, so i still have to wait till a get a new led before i can put it together for calibration.

6

CP4500 Stereo Bus Compressor / Re: burned led

« on: January 13, 2021, 09:24:25 PM »

hi, sorry but so far i did not figure out the problem, all seem ok, but here what questioning me about, on the meter itself does the blue and red short be shorted, cause taken it on the open the meter and i have a short between those two. it is not coming from the connector

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SK25/SK99 Discrete Op-Amp / Re: getting hot or not

« on: January 13, 2021, 08:35:26 PM »

On my jig i send 15.1 DCV to the Opamp.
I dbl check and redone the soldering on all the opamps and are now perfectly working, was simple, the soldering between the main pcb and both power transformer pcb is crucial. Perhaps there is need to specified this important info in the build document. Anyway it is now all good.

Thank you JP for your quick answer.

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EQP501 Passive Equalizer / Re: EQ worked for awhile then stopped

« on: January 13, 2021, 04:54:36 AM »

Hi did you notice how hot the op-amp was running?, cause i  just build 4 of them and using a test jig,  i notice that 3 o them run very hot, one is cool, perhaps to hot make the whole opamp to fried also.

9

SK25/SK99 Discrete Op-Amp / getting hot or not

« on: January 12, 2021, 08:35:00 PM »

Hi wondering if the SK25 is suppose to get hot, I mean real hot, I build 4 and 3 of them get pretty damn hot, the 4th one not at all. I'm talking about the Q9 BD139 NPN power transistor.

Also just to add here, I'm using a test jig, so to not burn anything on the module, the one that is cool, seem to give little more output judging by the reading of the oscilloscope. the other three are similar to each other.

10

CP4500 Stereo Bus Compressor / burned led

« on: January 03, 2021, 09:49:02 PM »

Hi just build the CP4500, ready to test, so far so good, plugin the my extender like i normally do with all my build, once i power it up i notice that the led on the meter goes on right away, no big deal perhaps, i start testing all the points like normal procedure, all report correct, then i push the in button, green led flashes an guess what burn out right away, i tested and notice that i get -16v on the negative led of the led, the led of the meter are not burned but they are always on tho! any idea where is my problem?