It is currently Mon Mar 16, 2020 2:16 pm

All times are UTC - 7 hours



Post new topic Reply to topic  [ 13 posts ] 
Author Message
Post subject: 5F1 Champ Clone Help!
Posted: Fri Oct 09, 2009 6:51 am
Offline
Professional Musician
Professional Musician
User avatar

Joined: Mon Feb 25, 2008 8:47 am
Posts: 2967
Location: Westchester County, NY
Hey guys,

I have a 5F1 Champ clone, the last 2 times I have powered on the amp I noticed a blue flash coming from the back of the amp. I have kept it on and played through anyway and it performs as usual, the tubes are glowing orange.

Am I about to blow a tube or could it be something worse?


Top
Profile
Fender Play Winter Sale 2020
Post subject:
Posted: Fri Oct 09, 2009 10:32 am
Offline
Rock Star
Rock Star
User avatar

Joined: Mon Oct 20, 2008 10:36 am
Posts: 3219
Location: Las Vegas
Have you tried looking back there while turning it on to see where it is coming from? Because, that blue flash is from current arching across something and eventually, whatever it is, it is going to short out and stop working.


Top
Profile
Post subject:
Posted: Fri Oct 09, 2009 10:48 am
Offline
Professional Musician
Professional Musician
User avatar

Joined: Mon Feb 25, 2008 8:47 am
Posts: 2967
Location: Westchester County, NY
Havent looked in the back yet. First time it happened, thought I may have just seen something. Yesterday it did again and I knew I didnt imagine. I left it on and looked in the back and all the tubes looked normal, play though as usual and didnt notice anything.

Tonight I will look in the back as I turn it on.

I changed the power supply once on that amp. I doubt it would be that again since the fuse didnt blow.

I'll be ordering a 12AX7, 6V6 and 5Y3 soon :)


Top
Profile
Post subject:
Posted: Fri Oct 09, 2009 5:37 pm
Offline
Hobbyist
Hobbyist
User avatar

Joined: Mon Sep 14, 2009 11:57 am
Posts: 56
Make sure it is a blue flash that is from the electronics. Is there a smell? I ask because I had a tweed style amp that looked like it had a flash and it turned out to be the pilot lite bulb flashing for some reason when you turned on the amp, not the electronics. Post back when you check it out!!

_________________
www.300guitars.com


Top
Profile
Post subject:
Posted: Fri Oct 09, 2009 5:46 pm
Offline
Professional Musician
Professional Musician
User avatar

Joined: Mon Feb 25, 2008 8:47 am
Posts: 2967
Location: Westchester County, NY
Ok, I played through that amp earlier for about an hour. The blue flash happened when I turned it on, came from the 5Y3 rectifier tube but again the amp operated normally.

I took all tubes out, cleaned and put back on.

I still want to get some new tubes in since I currently function with no spares. I know how cathode bias can eat tubes although I've been lucky so far. Especially considering I am running it at 8 all the time.

Ok, now, next question, does a cathode bias amp needs to be re biased when changing the power tube?


Top
Profile
Post subject:
Posted: Fri Oct 09, 2009 6:02 pm
Offline
Hobbyist
Hobbyist
User avatar

Joined: Mon Sep 14, 2009 11:57 am
Posts: 56
Change the rectifier tube asap. Get an NOS 5Y3. It will last for a looooong time. You do not have to mess with the bias on a cathode biased amp. What value resistor are you using? And what value cap are you bypassing it with?

_________________
www.300guitars.com


Top
Profile
Post subject:
Posted: Fri Oct 09, 2009 6:24 pm
Offline
Professional Musician
Professional Musician
User avatar

Joined: Mon Feb 25, 2008 8:47 am
Posts: 2967
Location: Westchester County, NY
I think you are looking for those values,the resistor is 470 ohms and the cathode is at 25v.

So, that would be 25/470 = 0.053A or 53mA tube current?

After that I am pretty much lost with what to do with that number :)

What would happen if that 5Y3 blew, could I do damage to the amp? Should I not run the amp at all until I get a replacement tube?


Top
Profile
Post subject:
Posted: Fri Oct 09, 2009 8:27 pm
Offline
Hobbyist
Hobbyist
User avatar

Joined: Mon Sep 14, 2009 11:57 am
Posts: 56
Your values and numbers are fine. If the rectifier tube "blew" it may cause damage if it shorted out. I do not think that this would happen and the fuse should open before damage could occur. I'd just be careful and get a new 5Y3 asap and get back to enjoying your amp.

_________________
www.300guitars.com


Top
Profile
Post subject:
Posted: Sat Oct 10, 2009 7:23 am
Offline
Professional Musician
Professional Musician
User avatar

Joined: Mon Feb 25, 2008 8:47 am
Posts: 2967
Location: Westchester County, NY
Cool, will order all new tubes asap.

I was thinking TungSol for power and preamp. Any recommendations?

Anyone knows where to get good tube in NYC area or do I have to order online? Freaking GC doesnt have to much choice, dont really want to throw GT or Sovtek in.


Top
Profile
Post subject:
Posted: Sat Oct 10, 2009 4:23 pm
Offline
Professional Musician
Professional Musician

Joined: Fri Jun 26, 2009 6:53 pm
Posts: 2252
Location: Harvard IL
Yep, I'd get a NOS 5Y3 right away. The blue flash is ionized gas. This tube is direct heated, no filament, the cathode is the heater. As for the 6V6, I'd also get a NOS RCA or the like. ART

_________________
None of Us are free, if One of Us is chained !


Top
Profile
Post subject:
Posted: Sat Oct 10, 2009 5:36 pm
Offline
Professional Musician
Professional Musician
User avatar

Joined: Mon Feb 25, 2008 8:47 am
Posts: 2967
Location: Westchester County, NY
Played again today, didnt see the flash this time. Weird, anyway I ordered a NOS 5Y3GT, a TungSol 12AX7 and a TungSol 6V6GT. I think I may get the itch now of experimenting with different tubes.


Top
Profile
Post subject:
Posted: Sun Nov 01, 2009 12:18 pm
Offline
Professional Musician
Professional Musician
User avatar

Joined: Sat Dec 13, 2008 11:49 am
Posts: 1153
Location: South Bay, CA
I have yet to go wrong with Mike K at www.kcanostubes.com.


Top
Profile
Post subject:
Posted: Sun Nov 01, 2009 3:58 pm
Offline
Professional Musician
Professional Musician
User avatar

Joined: Mon Feb 25, 2008 8:47 am
Posts: 2967
Location: Westchester County, NY
I bought mine from http://thetubestore.com/ no problem there, fast and secure shipping even across the border.


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 13 posts ] 

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: