It is currently Tue Mar 17, 2020 1:01 am

All times are UTC - 7 hours



Post new topic Reply to topic  [ 37 posts ]  Go to page 1, 2, 3  Next
Go to page 1, 2, 3  Next
Author Message
Post subject: Blue Deluxe Reissue Tube Replacement
Posted: Sun Dec 02, 2012 11:21 am
Offline
Hobbyist
Hobbyist

Joined: Sun Dec 02, 2012 10:53 am
Posts: 13
Hi Fender people! I'm new to tis forum and this is my first post. I have been a Fender fan for 35 years. I have a 90's P-Lyte, a 68 Mustang bass, an all original 48 Deluxe amp, an EJ strat, a Mexi-strat, and recently a Blue Deluxe reissue amp. My problem is this: I began losing power, and then finally lost power. I switched out my power tubes with some Sovteks and that didn't cure the problem. So I put the Groove Tube 6L6's back in and went for the preamp tubes next. I ordered some GT-12ax7-C preamp tubes and put them in. I now have sound, but the volume is a lot lower and the tubes distort too soon. I like the Fender clean sound and I don't want it to distort so soon. I loved this amp right out of the box, how can I get it to sound like that again? I'm new to trying to fix tube amps and don't know if I am supposed to readjust the bias when changing tubes or how to do it. Thanks. :D


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: Blue Deluxe Reissue Tube Replacement
Posted: Sun Dec 02, 2012 12:28 pm
Offline
Hobbyist
Hobbyist

Joined: Sat Dec 01, 2012 1:06 pm
Posts: 12
Have you tried putting the New Sovteks back in since you replaced the 12AX7's?


Top
Profile
Post subject: Re: Blue Deluxe Reissue Tube Replacement
Posted: Sun Dec 02, 2012 12:45 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
royjulius wrote:
Hi Fender people! I'm new to tis forum and this is my first post. I have been a Fender fan for 35 years. I have a 90's P-Lyte, a 68 Mustang bass, an all original 48 Deluxe amp, an EJ strat, a Mexi-strat, and recently a Blue Deluxe reissue amp. My problem is this: I began losing power, and then finally lost power. I switched out my power tubes with some Sovteks and that didn't cure the problem. So I put the Groove Tube 6L6's back in and went for the preamp tubes next. I ordered some GT-12ax7-C preamp tubes and put them in. I now have sound, but the volume is a lot lower and the tubes distort too soon. I like the Fender clean sound and I don't want it to distort so soon. I loved this amp right out of the box, how can I get it to sound like that again? I'm new to trying to fix tube amps and don't know if I am supposed to readjust the bias when changing tubes or how to do it. Thanks. :D


Yes, you need to check and adjust the bias for the power tubes when you change them. This sounds like more than just an improperly biased output stage. If you have no real experience troubleshooting a tube amp, you should take the amp to a qualified tech for evaluation and repair. You have a 5 year warranty if you bought the amp new.

_________________
Bill

Image


Top
Profile
Post subject: Re: Blue Deluxe Reissue Tube Replacement
Posted: Sun Dec 02, 2012 5:12 pm
Offline
Hobbyist
Hobbyist

Joined: Sun Dec 02, 2012 10:53 am
Posts: 13
Thanks guys. I just tried the new Sovteks and same issue still. I guess maybe I need to take the amp in. I'm an electronic technician by trade, so I was hoping I could figure this one out. I can't figure out why putting the exact same preamp tubes in will not give me the sound I had before. Do you think it is something besides tubes? It had all the symptoms of tubes failing, but the amp is only a year old so I thought that was odd.


Top
Profile
Post subject: Re: Blue Deluxe Reissue Tube Replacement
Posted: Sun Dec 02, 2012 5:29 pm
Offline
Professional Musician
Professional Musician
User avatar

Joined: Thu Oct 14, 2010 8:54 am
Posts: 1179
Location: Florida
I would first make sure that all tube sockets are clean and then start replacing tubes starting with V1. If you don't have any test equipment at home, it's hard to do much else except maybe pull the chassis and make a visual inspection (bad solder joints, etc.) TURN IT OFF AND UNPLUG IT FIRST!

Art


Top
Profile
Post subject: Re: Blue Deluxe Reissue Tube Replacement
Posted: Sun Dec 02, 2012 5:39 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
royjulius wrote:
Thanks guys. I just tried the new Sovteks and same issue still. I guess maybe I need to take the amp in. I'm an electronic technician by trade, so I was hoping I could figure this one out. I can't figure out why putting the exact same preamp tubes in will not give me the sound I had before. Do you think it is something besides tubes? It had all the symptoms of tubes failing, but the amp is only a year old so I thought that was odd.


Given that you have replaced all of the tubes with new ones and the problem was not solved, I would say that tubes are not the issue. The only symptom you mentioned was a loss of power. Without a better description of the problem or other symptoms and lacking any measurements, it is impossible to make a diagnosis on-line. If you are confident in following basic troubleshooting procedures, here is the amp schematic:

http://support.fender.com/schematics/gu ... _Rev-A.pdf

You might also want to refer to a thread I am currently working on regarding modifications I have made to my BDRI. It references a number of troubleshooting steps I have taken.

viewtopic.php?f=13&t=80142&p=911995#p911995

_________________
Bill

Image


Last edited by bluesky636 on Wed Dec 12, 2012 10:02 pm, edited 1 time in total.

Top
Profile
Post subject: Re: Blue Deluxe Reissue Tube Replacement
Posted: Mon Dec 03, 2012 6:48 am
Offline
Hobbyist
Hobbyist

Joined: Sun Dec 02, 2012 10:53 am
Posts: 13
Thanks. I'll just take it in since it's under warranty.


Top
Profile
Post subject: Re: Blue Deluxe Reissue Tube Replacement
Posted: Mon Dec 03, 2012 7:20 am
Offline
Hobbyist
Hobbyist

Joined: Sat Dec 01, 2012 1:06 pm
Posts: 12
Here is a youtube video on how to bias your amp - it's very easy. I disaggree with the range he gave of 70 - 90ma for biasing. I went with 68ma and it's perfect.

http://www.youtube.com/watch?v=sD_s5fCmalA

If the biasing is correct and you still have loss of power then I would take it in for warranty. Keep us posted.

Take care and be safe !!!!


Top
Profile
Post subject: Re: Blue Deluxe Reissue Tube Replacement
Posted: Mon Dec 03, 2012 8:21 am
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
waswell wrote:
Here is a youtube video on how to bias your amp - it's very easy. I disaggree with the range he gave of 70 - 90ma for biasing. I went with 68ma and it's perfect.

http://www.youtube.com/watch?v=sD_s5fCmalA

If the biasing is correct and you still have loss of power then I would take it in for warranty. Keep us posted.

Take care and be safe !!!!


Taking a measurement of 68 mV (or 70 mV or 90 mV) without measuring the plate voltage does not mean that your amp is properly biased. You need to determine the percentage of maximum plate dissipation of the power tubes at idle. The normal range is 50% to 70% of maximum plate dissipation.

If you set you bias at 68 mV (which is actually 34 mA cathode current per tube) and the plate voltage is 430 VDC, the tube is running at about 14 watts idle which is less than 50% of the maximum plate dissipation for a 30 watt 6L6GC. That is way to cold in my opinion and will sound brittle and sterile. I run my BDRI at 52 mA cathode current per tube at a plate voltage of 402 VDC which gives you an idle power dissipation of about 20 watts or 67% of maximum plate dissipation. My 5F6A clone is set at 51 mA cathode current per tube at 427 VDC plate voltage which works out to about 21 watts at idle or 70% of maximum plate dissipation with 6L6GC power tubes.

If you are going to bias an amp properly, you MUST measure BOTH the cathode current AND the plate voltage at your chosen bias set point. Not doing so is totally meaningless.

_________________
Bill

Image


Top
Profile
Post subject: Re: Blue Deluxe Reissue Tube Replacement
Posted: Mon Dec 03, 2012 9:24 am
Offline
Hobbyist
Hobbyist

Joined: Sun Dec 02, 2012 10:53 am
Posts: 13
I don't think the problem is the power tubes. My amp was totally dead, so I switched out the power tubes with Sovteks and it was still dead. So then I switched out the preamp tubes with JJ Mesa Boogie 12ax7s because my local shop sold them. Now I have sound, but at about half volume and distorting too early. I put the old groove tube power tubes back in and same thing, low volume, early distortion. So I figure if I get the original GT-12ax7-Cs back in for preamp tubes I'll be in business. Not so. I ordered new ones and put them in and it does the same thing as with the JJ preamp tubes. Low volume, distorts too soon.


Top
Profile
Post subject: Re: Blue Deluxe Reissue Tube Replacement
Posted: Mon Dec 03, 2012 11:02 am
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
royjulius wrote:
I don't think the problem is the power tubes.


I think that's pretty obvious. :wink:

_________________
Bill

Image


Top
Profile
Post subject: Re: Blue Deluxe Reissue Tube Replacement
Posted: Mon Dec 03, 2012 11:41 am
Offline
Hobbyist
Hobbyist

Joined: Sun Dec 02, 2012 10:53 am
Posts: 13
Thank you guys for the advice. I'm gonna take 'er in and see what the expert says. I will post how it turns out, and I will be hanging around this site. It's purdy cool!


Top
Profile
Post subject: Re: Blue Deluxe Reissue Tube Replacement
Posted: Mon Dec 03, 2012 1:34 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
Smart move and good luck. :D

_________________
Bill

Image


Top
Profile
Post subject: Re: Blue Deluxe Reissue Tube Replacement
Posted: Mon Dec 10, 2012 7:41 am
Offline
Hobbyist
Hobbyist

Joined: Sun Dec 02, 2012 10:53 am
Posts: 13
Today I will drop my amp off at the shop. Just wanted to give an update.


Top
Profile
Post subject: Re: Blue Deluxe Reissue Tube Replacement
Posted: Wed Dec 12, 2012 6:10 pm
Offline
Hobbyist
Hobbyist

Joined: Sun Dec 02, 2012 10:53 am
Posts: 13
Ok, here's a little game. I got my amp back and it sounds so good I almost teared up. It cost nothing to fix. It wasn't the tubes. Anybody got a guess? hint:(it has to do with the load, and my investigation into a power soak)


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 37 posts ]  Go to page 1, 2, 3  Next
Go to page 1, 2, 3  Next

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: