Sound Skulptor forums

Build help and troubleshooting => MU524 Vari-Mu Tube Compressor => Topic started by: bankey5_s@hotmail.com on October 09, 2023, 06:41:33 PM

Title: MU 524 build problems
Post by: bankey5_s@hotmail.com on October 09, 2023, 06:41:33 PM

So I have had nothing but problems with this build.  

right now on the tube heater slow start test. i am getting 2.5 dcv with the tube in and 33.5 dcv with the volts removed. i took the tube that was sent in to a local electronics place that has a tester for that tube and it didnt check out so i know its bad.  I was able to find a replacement and its being sent but my questions are is that normal to get those readings i got? or is something else wrong?  

audio paths check i have hooked up to pin 2,4 on the xt500 and set a 1.0 khz sine wave but when engaging the compressor that promptly drops to 0.  i increase the output and can get 2.0 volts ac but i am also wondering if that is normal or if that is because the tube is bad?  all the power voltage checks have passed with the values as in the guide.  i havent been able to move past those tests yet.  

thanks for the help 

Title: Re: MU 524 build problems
Post by: JPK on October 11, 2023, 11:04:56 AM

on the tube heater slow start test. i am getting 2.5 dcv with the tube in and 33.5 dcv with the volts removed.
You can try to shunt R39 (18R) with a little wire to remove the slow start circuit.

i am also wondering if that is normal or if that is because the tube is bad?
If the tube doesn't get the proper heater voltage, it is normal that all the other results are wrong.

i took the tube that was sent in to a local electronics place that has a tester for that tube and it didnt check out so i know its bad.
If confirmed, we will send you a new tube.

Title: Re: MU 524 build problems
Post by: bankey5_s@hotmail.com on October 13, 2023, 04:47:21 AM

first off i dont know what a shunt is and why am i bypassing it? shouldnt it work? also the tube heater test just went from 33.3dcv to 6.3 dcv and now 0 dcv right before my eyes with the meter on it.  I have resoldered everything including checking and going through your checklist you put on here multiple times.  one time i was able to get over 7 vac at the output and then now i cant get any without anything even changing.  very dissapointed with this company and this product. 

Title: Re: MU 524 build problems
Post by: JPK on October 16, 2023, 09:02:52 AM

If you are stuck troubleshooting your mu524, I recommend sending it to us for verification. Contact me here (https://www.soundskulptor.com/en/content/6-contact).