Another Fender on the bench.

Netlist · 5th March 2004, 06:13 PM

Looking at the schematic: http://www1.korksoft.com/~schem/fend..._100_schem.pdf at V5A, V5B I measure some strange values.
1) 364
2) –39.5
3) 0

6) 309
7) -39.5
8) 0

I measured all resistors surrounding the tube and replaced it with the 7025’s. I tried several of them, V1, V2, V4, same result.
The only cap I changed was the 5 uF at pin 8, with a 4.7µF.
What could be wrong?

Thanks

Netlist · 5th March 2004, 08:09 PM

Sorry, wrong schematic: It should be the 135W.
http://www1.korksoft.com/~schem/fend..._135_schem.pdf

So why is the 1.8V and the 12V missing on both cathodes?

SHiFTY · 6th March 2004, 07:15 AM

Sounds like the tube is not drawing any current, has it lost the ground connection or the cathode resistors gone bad?

Netlist · 6th March 2004, 08:03 AM

Thanks, I forgot to connect the vibrato pedal. When on, the tube turns on as well.

5th March 2004, 06:13 PM	#1
Netlist diyAudio Moderator Emeritus Join Date: Jan 2003	Another Fender on the bench. Looking at the schematic: http://www1.korksoft.com/~schem/fend..._100_schem.pdf at V5A, V5B I measure some strange values. 1) 364 2) –39.5 3) 0 6) 309 7) -39.5 8) 0 I measured all resistors surrounding the tube and replaced it with the 7025’s. I tried several of them, V1, V2, V4, same result. The only cap I changed was the 5 uF at pin 8, with a 4.7µF. What could be wrong? Thanks

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Bench testing a SA/4e	arnyk@comcast.n	Pass Labs	1	6th January 2010 07:43 PM
Bench PSU	sorenj07	Tubes / Valves	5	19th February 2007 10:53 PM
Bench PSU for tubes	Mr. Triatic	Tubes / Valves	12	22nd June 2006 01:13 AM
Bench Supply	jonclancy	Parts	4	22nd September 2004 04:36 PM
Regulated bench PSU	UrSv	Parts	84	24th September 2003 11:53 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

5th March 2004, 08:09 PM	#2
Netlist diyAudio Moderator Emeritus Join Date: Jan 2003	Sorry, wrong schematic: It should be the 135W. http://www1.korksoft.com/~schem/fend..._135_schem.pdf So why is the 1.8V and the 12V missing on both cathodes?

6th March 2004, 07:15 AM	#3
SHiFTY diyAudio Member Join Date: Jul 2002 Location: New Zealand	Sounds like the tube is not drawing any current, has it lost the ground connection or the cathode resistors gone bad?

6th March 2004, 08:03 AM	#4
Netlist diyAudio Moderator Emeritus Join Date: Jan 2003	Thanks, I forgot to connect the vibrato pedal. When on, the tube turns on as well.