It is currently Mon Mar 16, 2020 1:46 pm

All times are UTC - 7 hours



Post new topic Reply to topic  [ 15 posts ] 
Author Message
Post subject: Blues Jr valve problem - flashes of light, loud noise
Posted: Mon Jan 11, 2016 2:03 pm
Offline
Hobbyist
Hobbyist

Joined: Mon Oct 15, 2012 2:37 pm
Posts: 3
This has been happening since yesterday - crazy noise and flashes of light inside an output valve

https://www.youtube.com/watch?v=4cmoLDm ... e=youtu.be

I have not had a chance to get my hands on a replacement output valve and swap it yet, but has anyone ever experienced something like this ?

Thanks
G


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: Blues Jr valve problem - flashes of light, loud noise
Posted: Mon Jan 11, 2016 2:21 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
Looks to be a shorted tube. Replace it immediately. If it's a EL84 power tube, those should be replaced in pairs using a matched set.

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: Blues Jr valve problem - flashes of light, loud noise
Posted: Mon Jan 11, 2016 4:34 pm
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Fri Feb 06, 2015 10:21 pm
Posts: 393
Location: Oklahoma
GregChiche wrote:
- crazy noise and flashes of light inside an output valve
Whoa! That would have scared the bejeebers out of me. Hope there's no damage, other than perhaps the tubes.


Top
Profile
Post subject: Re: Blues Jr valve problem - flashes of light, loud noise
Posted: Mon Jan 11, 2016 6:41 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
LawFlow wrote:
Whoa! That would have scared the bejeebers out of me.


+1

Doubly so if such detonation is accompanied by the wisp of "magical and mystical" blue smoke.

:shock:

I hate it when that happens.

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: Blues Jr valve problem - flashes of light, loud noise
Posted: Tue Jan 12, 2016 2:52 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
Retroverbial wrote:
Looks to be a shorted tube. Replace it immediately. If it's a EL84 power tube, those should be replaced in pairs using a matched set.

Arjay



With a bias check and adjust, a must , it is not a cathod resistor.

Schematic here;

http://support.fender.com/schematics/gu ... ematic.pdf


Top
Profile
Post subject: Re: Blues Jr valve problem - flashes of light, loud noise
Posted: Thu Jan 28, 2016 5:13 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Mon Jun 30, 2008 10:47 am
Posts: 15336
Location: In a galaxy far far away
But it is fixed bias Stratele.
Get low current draw valves.
Check the bias resistors and the resistors coming off the 2nd grid (pin9) R20,23,24 and 25.
Or have someone do it for you. Entirely possible a shorted valve could take one out.
All the best, they're pretty solid. I can't see it being more than a couple of valves.

_________________
No no and no


Top
Profile
Post subject: Re: Blues Jr valve problem - flashes of light, loud noise
Posted: Thu Jan 28, 2016 5:29 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
nikininja wrote:
But it is fixed bias Stratele.
I know.
You mean there is no adjustment pot ? Yes , cost cutting and / or for qualified person only



.


Top
Profile
Post subject: Re: Blues Jr valve problem - flashes of light, loud noise
Posted: Thu Jan 28, 2016 10:03 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Mon Jun 30, 2008 10:47 am
Posts: 15336
Location: In a galaxy far far away
I wouldn't call it cost cutting mate. My Mesa is fixed bias and cost an obscene amount of money.
The cost difference of about 2cents Euro with the quantities Fender buy at a time. For a bias pot. And labour wouldn't be much more. Putting it onto the circuitboard wouldn't cost any extra. And bias is checked at the end of the burn in, isn't it?

In that Blues Jr circuit. You can really push the limits of the valves with fixed bias and bring it up to nearer 20watts output.

_________________
No no and no


Top
Profile
Post subject: Re: Blues Jr valve problem - flashes of light, loud noise
Posted: Thu Jan 28, 2016 10:12 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
nikininja wrote:
I
The cost difference of about 2cents Euro with the quantities Fender buy at a time. For a bias pot. And labour wouldn't be much more. Putting it onto the circuitboard wouldn't cost any extra. And bias is checked at the end of the burn in, isn't it? t.



That is you opinon , not mine.


Top
Profile
Post subject: Re: Blues Jr valve problem - flashes of light, loud noise
Posted: Thu Jan 28, 2016 12:12 pm
Offline
Rock Star
Rock Star

Joined: Wed Apr 11, 2012 7:37 am
Posts: 4099
Location: New York
Is that some of the "magic" my modeling amp can't duplicate? :lol: Oh well, I can always tape a roman candle behind it for the authentic experience.

_________________
Please subscribe to my Image Channel!
https://www.youtube.com/user/b7567


Top
Profile
Post subject: Re: Blues Jr valve problem - flashes of light, loud noise
Posted: Thu Jan 28, 2016 12:28 pm
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Fri Feb 06, 2015 10:21 pm
Posts: 393
Location: Oklahoma
strings10927 wrote:
......some of the "magic" my modeling amp can't duplicate
OK, I must remember this the next time my Twin Reverb explodes. Holding my breath until then. :lol:


Top
Profile
Post subject: Re: Blues Jr valve problem - flashes of light, loud noise
Posted: Sun Aug 27, 2017 11:18 pm
Offline
Hobbyist
Hobbyist

Joined: Mon Jan 09, 2012 3:12 am
Posts: 4
Hi,

were you able to fix the problem and identify the root cause? I got the exact same thing on my Blues Junior III, one of the power tubes fried out, a lot of noise and flashing tube exactly as in your video . I replaced the power tubes but after 3/4 months the exact same thing happened again.

Cheers,

Tom


Top
Profile
Post subject: Re: Blues Jr valve problem - flashes of light, loud noise
Posted: Mon Aug 28, 2017 2:07 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
One post and he never come back after we gave many answers :(

On both EL84;
Check 100 ohms resistor at pins 9
Check diode on pins 7
Check voltage at pin 2, you must read close to minus 11 volts DC ( - 11 VDC ) or more ( -12, -13 )
Always check bias with new output tubes and adjust with the help of a tech.


Top
Profile
Post subject: Re: Blues Jr valve problem - flashes of light, loud noise
Posted: Mon Aug 28, 2017 11:05 pm
Offline
Hobbyist
Hobbyist

Joined: Mon Jan 09, 2012 3:12 am
Posts: 4
Thanks for the answer but quite too technical for me. :oops: I'll try to find an amp tech in my area.

Cheers,

Tom


Top
Profile
Post subject: Re: Blues Jr valve problem - flashes of light, loud noise
Posted: Tue Aug 29, 2017 2:16 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
tgommes wrote:
Thanks for the answer but quite too technical for me. :oops: I'll try to find an amp tech in my area.

Cheers,

Tom


Find a well know tech, too many unqualified person work on amps.


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 15 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: