SOLVED Cleaver no sound or fuzzy

christomania

New member
Hi,


I've just built a Cleaver Kit and I have a problem with it:
  • I cannot bias to 1/2 supply, about 9v. Trimpots allow from 17v to 14v
  • There is no sound but a big buzz.

I read somewhere to try to turn the FET 180° --> I can bias to 9v at the end of trim but I have a very fuzzy/distorded sound.
Any idea ?



Regards

IMG_20220502_232745.jpg

IMG_20220502_232906.jpg
 

Feral Feline

Well-known member
Right, jack to metal case, but is the output jack grounded to the case? Did you test that it is? Hmm bare case so it's not paint-interference...

Everything looks good; attention to detail such as you even have your resisters matched in orientation...

Maybe clean the PCB so you can inspect the solder joins more closely for a bridge?

If you've got extra transistors and another IC maybe try swapping those out. I was focused on the "big buzz", but re-reading the OP, biasing supply seems to be more the spanner in the works; try another IC.
 

Feral Feline

Well-known member
I think Music6000 is on to something. Try turning the jacks (particularly the output) 180º.

I built a tight 1590B once and had the ground tabs facing/touching the enclosure.

PS: As I recall, the Lumberg-style jacks get pushed out big time by the plug — maybe with a cable's plug inserted the tip-prong(s) is/are being pushed far enough to make contact with the case...
 

christomania

New member
Right, jack to metal case, but is the output jack grounded to the case? Did you test that it is? Hmm bare case so it's not paint-interference...
The enclosure is bare metal, the grouding is good
If you've got extra transistors and another IC maybe try swapping those out. I was focused on the "big buzz", but re-reading the OP, biasing supply seems to be more the spanner in the works; try another IC.
The IC is the pump charge, I get ~17V so I think it is good. I ordered some spare of JFET, I'll check that
 

christomania

New member
I think Music6000 is on to something. Try turning the jacks (particularly the output) 180º.
It is a good advise, I could turn the 2 jacks to get the signal "inside" and not outside, in that case, the only wire that can touch the case is the ground already in contact with it.
I built a tight 1590B once and had the ground tabs facing/touching the enclosure.

PS: As I recall, the Lumberg-style jacks get pushed out big time by the plug — maybe with a cable's plug inserted the tip-prong(s) is/are being pushed far enough to make contact with the case...
I rechecked my build just know with a jack inserted, no problem here.
 

music6000

Well-known member
I don't know, I have them in a case from a long time

I have a peak DCA75
Hook any 3 leads on to the transistor legs & TEST for confirmation if it is a Legit 2N5458 ????

2n5458-transistor-pinout-equivalent.gif
 
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