Checking caps, op amps, transistors in circuit?
« on: October 21, 2008, 03:40:01 AM »
Im having a noise issue on the collector leg of one of my transistors
I have been told to check the caps, op amps and transistors around it
As im new to the world of electronics, how do i go about checking these in circuit?
Thanks
Paul


CJ

Checking caps, op amps, transistors in circuit?
« Reply #1 on: October 21, 2008, 05:47:25 AM »
What are you working on?
Tell us the model and maybe we can dredge up a circuit diagram.

Be careful around the transistors with the power on.
One slip of the probe and it could get zapped.
If I can't fix it, I can fix it so nobody else can!
Frank's Tube Page: www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar Amps: http://bmamps.com/Tech_sch.html

Checking caps, op amps, transistors in circuit?
« Reply #2 on: October 21, 2008, 06:21:34 AM »
Studiomaster 16 4 8
Some of the channels have a lot of noise(white noise)and it seems to be coming from the collector leg of one of the resistors
http://i390.photobucket.com/albums/oo345/paulrichards7/Channeltrans.jpg
I have put a red ring around the culprit
Ive been told to check the opamps & caps around the transistor as well as the transistor, but I dont know how to do this
Thanks
Paul

CJ

Checking caps, op amps, transistors in circuit?
« Reply #3 on: October 21, 2008, 06:31:09 AM »
A common problem is those coupling caps getting noisy.
That would be the cap with the + sign, up and to the left of the transistor.

Simply find the same value, at or above the same voltage rating, and swap it out.

If no joy, it might be the transistor itself.

Resistors do make noise, all the ones that I have seen do this are in high voltage tube circuits.

There might be a Parts Meta if you need to order something.

If you would rather check the cap before ordering, but do not have a cap tester:

http://www.groupdiy.com/index.php?topic=24434&highlight=leakage+checker
If I can't fix it, I can fix it so nobody else can!
Frank's Tube Page: www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar Amps: http://bmamps.com/Tech_sch.html

Checking caps, op amps, transistors in circuit?
« Reply #4 on: October 21, 2008, 07:28:46 AM »
Cool thanks for that
do you recommend a higher voltage?
thanks again
paul


 

Related Topics

  Subject / Started by Replies Last post
2 Replies
1389 Views
Last post April 20, 2005, 03:07:38 PM
by peterc
6 Replies
2100 Views
Last post June 21, 2007, 12:03:35 PM
by Purusha
8 Replies
1942 Views
Last post November 09, 2007, 01:04:37 AM
by jtoole
0 Replies
1131 Views
Last post November 19, 2010, 11:56:56 AM
by stitch-o