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Post subject: 50's Bassman (Original) not re-issue - Recap and Problems
Posted: Wed Dec 17, 2014 12:47 pm
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So I changed out all the Caps on this sweet baby, turned her on and she sounded GREAT!!!!

After 5 minutes....FLASH no power.

Changed fuse, FLASH again (not a light flash) but fried fuse.

Pulled all tubes FLASH again.

Found Bad Diodes used as a Bridge Rectifier on one of the Rectifier Tube Sockets (it has 2 Rectifier Tubes)

Replaced the Diodes, and now she powers up fine but I dont want to run it.......why did the DIODES FRY?



Any ideas?

Thanks Guys


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Post subject: Re: 50's Bassman (Original) not re-issue - Recap and Problem
Posted: Thu Dec 18, 2014 2:15 am
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Did you heat diodes when working on caps ? I guess you can't .

Which new caps do you put ? Good quality like F & T or low budget ?
Did you use the same value ? Higher value need more current from diode.

Maybe first time caps fire up they need too much current for the very old diodes wich work hard since long time.
Check polarity of you caps.

If everything look OK , I'm sure your amp is good for long life now.


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Post subject: Re: 50's Bassman (Original) not re-issue - Recap and Problem
Posted: Thu Dec 18, 2014 6:34 am
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stratele52 wrote:
Maybe first time caps fire up they need too much current for the very old diodes wich work hard since long time.



+1

Ryan41018 wrote:
Found Bad Diodes used as a Bridge Rectifier on one of the Rectifier Tube Sockets (it has 2 Rectifier Tubes)



:?: :?: :?: Diode bridge rectifier on rectifier tube socket? Holy Department of Redundancy Department, Batman :!:

vinyl


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Post subject: Re: 50's Bassman (Original) not re-issue - Recap and Problem
Posted: Thu Dec 18, 2014 6:54 am
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This solid State Rectifier ?


https://www.tubesandmore.com/products/T-SSR01


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Post subject: Re: 50's Bassman (Original) not re-issue - Recap and Problem
Posted: Fri Dec 19, 2014 12:12 pm
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Its not a S.S. Rectifier. It run to Rectifier Tubes. But Fender also set up a Bridge Rectification Circuit using diodes.

Its not blowing fuses anymore BUT.....its gotta a hum now so I flip the switch off to avoid any damage.

Hum? Others small yellow caps? Maybe one I installed was/is defective?

Power tubes swapped for newer ones?


Thanks Guys


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Post subject: Re: 50's Bassman (Original) not re-issue - Recap and Problem
Posted: Fri Dec 19, 2014 1:03 pm
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Hum is only from the big filters caps , not the small one wich are bypass caps , not filter.
If one of your Output Power tube are weak , this may unbalace output section and do some hum

The only "small " filter cap may do hum is the bias caps .

One of your filter caps are defective , bad solder , reverse polarity or you forget to say something to us about the amp .

1- Post some picture of inside the amp .

2- Tell us what are the new filter caps , brand and value.

3- Did you have some hum before you put new filter caps ? Why did you change filter caps ?

Please answer to these questions , it will help to help you.


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Post subject: Re: 50's Bassman (Original) not re-issue - Recap and Problem
Posted: Fri Dec 19, 2014 1:55 pm
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stratele52 wrote:
Hum is only from the big filters caps , not the small one wich are bypass caps , not filter.
If one of your Output Power tube are weak , this may unbalace output section and do some hum

The only "small " filter cap may do hum is the bias caps .

One of your filter caps are defective , bad solder , reverse polarity or you forget to say something to us about the amp .

1- Post some pictures of inside the amp .

2- Tell us what are the new filter caps , brand and value.

3- Did you have some hum before you put new filter caps ? Why did you change filter caps ?

Please answer to these questions , it will help us to help you.


+1

As far as I know, there aren't any psychics on here. You've given us a clue that it's a '50s Bassman, and it has 2 rectifier tubes, and there are solid state diodes soldered to one of the rectifier tube sockets, and you think Fender did this.

Based on your other posts on other threads, you're charging people money for your "services", but don't seem to be willing to use the "Search" button to even find a schematic. If you had, you would have at least discovered that Fender didn't produce any amplifiers with solid state diodes soldered to the tube socket of a tube rectifier.

Do your homework. Before you become branded as a "hack". And don't expect answers based on little or no information.

Now I've gone and ended up sounding "harsh". I didn't mean to do that, but your best bet when trying to troubleshoot problems via the internet is to provide as much detail as possible

JMHO,
vinyl


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Post subject: Re: 50's Bassman (Original) not re-issue - Recap and Problem
Posted: Fri Dec 19, 2014 2:15 pm
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Thank's you vinyl for correcting my text.


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Post subject: Re: 50's Bassman (Original) not re-issue - Recap and Problem
Posted: Fri Dec 19, 2014 5:26 pm
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Yup - reverse polarity...........Vinyls post got me thinkin, went to look and he got it right 1 cap reversed, swaped around and hum is gone!

R


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Post subject: Re: 50's Bassman (Original) not re-issue - Recap and Problem
Posted: Fri Dec 19, 2014 5:36 pm
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Ryan41018 wrote:
Yup - reverse polarity...........Vinyls post got me thinkin, went to look and he got it right 1 cap reversed, swaped around and hum is gone!

R


Maybe that is why diodes blow as I wrote in my first answer ...check polarity

I wish to have answer to question no 2


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Post subject: Re: 50's Bassman (Original) not re-issue - Recap and Problem
Posted: Sat Dec 20, 2014 2:12 pm
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I suppose someone may have soldered a diode on unused pins of one of the rectifier tubes to replace a failed selenium rectifier for the bias supply.

Stratele52 is the one that got it right, not me. Maybe you'll have the decency to at least answer his questions.

stratele52 wrote:
Thank's you vinyl for correcting my text.


Stratele52,
Je espère que je ne vous ai pas offensé par la correction de votre texte. Je ne ai rien, mais de respect pour vous, monsieur.

vinyl


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Post subject: Re: 50's Bassman (Original) not re-issue - Recap and Problem
Posted: Sat Dec 20, 2014 2:47 pm
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vinyl wrote:
I suppose someone may have soldered a diode on unused pins of one of the rectifier tubes to replace a failed selenium rectifier for the bias supply.

Stratele52 is the one that got it right, not me. Maybe you'll have the decency to at least answer his questions.

stratele52 wrote:
Thank's you vinyl for correcting my text.


Stratele52,
Je espère que je ne vous ai pas offensé par la correction de votre texte. Je ne ai rien, mais de respect pour vous, monsieur.

vinyl


:D Non pas offensé du tout .

I learn how to write a better english .


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Post subject: Re: 50's Bassman (Original) not re-issue - Recap and Problem
Posted: Sun Dec 21, 2014 3:27 pm
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vinyl wrote:
I suppose someone may have soldered a diode on unused pins of one of the rectifier tubes to replace a failed selenium rectifier for the bias supply.

vinyl


I think this was part of a "fix-it" to add solid-state diodes to the tube rectifier. A well-known addition, added in case the tube rectifier shorts out.

Here's the diagram of how it should be hooked up.

Image


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Post subject: Re: 50's Bassman (Original) not re-issue - Recap and Problem
Posted: Thu Dec 25, 2014 3:57 pm
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Beemer,

Thanks for the enlightening post. After researching, this does seem like "cheap insurance for protecting a power transformer and filter caps" in some cases, if wired correctly.

Wishing you a joyous holiday season and a prosperous new year,
vinyl


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