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Post subject: Replacing filter caps
Posted: Thu Dec 18, 2014 9:48 am
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Aspiring Musician
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As suggested by a few of you, I think I am going to replace the filter caps on my DR. Before I order the parts I have a couple of questions for the experts.

There is a large price difference between the 16nf 475V F&T's and Sprague Atoms. Antique Electronics Supply is selling the F&T's for $5 & the Sprague's for $12. Are the Sprague Atoms that much better?

Also if the average useful life of a electrolytic capacitor is approximately 10 years, should I also replace the ones circled below?

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Post subject: Re: Replacing filter caps
Posted: Thu Dec 18, 2014 4:35 pm
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djwhitjr wrote:
As suggested by a few of you, I think I am going to replace the filter caps on my DR. Before I order the parts I have a couple of questions for the experts.

There is a large price difference between the 16nf 475V F&T's and Sprague Atoms. Antique Electronics Supply is selling the F&T's for $5 & the Sprague's for $12. Are the Sprague Atoms that much better?
No .
I alway use F & T since Sprague are too expensive and not better .



Also if the average useful life of a electrolytic capacitor is approximately 10 years, should I also replace the ones circled below?
IMO Good quality caps are good for 20 to 30 years .
10 years....look at home how old are your electronics stuff , 10 years is very very short .

Your amp is a Silverface with some cheap caps , Yes replace them all. Second picture ; this is a bias cap , use 100 mfd at 100 volts volts , not less.


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Post subject: Re: Replacing filter caps
Posted: Thu Dec 18, 2014 4:44 pm
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I agree with what stratele52 said. Also check the places I have circled in red, I think there may be a couple of more cathode bypass caps hiding there:

Image

Does this amp have a volume boost switch?

vinyl


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Post subject: Re: Replacing filter caps
Posted: Thu Dec 18, 2014 6:46 pm
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Yes Vinyl, the amp does have a boost on the volume knob.


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Post subject: Re: Replacing filter caps
Posted: Thu Dec 18, 2014 7:47 pm
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Aspiring Musician
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This should be the schematic for your amp:

http://bmamps.com/Schematics/fender/deluxe_reverb_boost_schem.pdf

Besides the 16uF F&T caps, you'll need 5 25uF and 1 5uF cap and the 100uF 100V cap that stratele52 mentioned. Your best bet for the 25uF caps is Sprague, 25 or 50 V rating. 50 V would be a little better. F&T doesn't make 25uF single caps. For the 5uF, get the closest to 5 uF you can find, like a 8uF 150V Sprague.

Pay careful attention to the polarity of the bias supply cap, (100 uF, 100V cap) in second picture, the positive side will go to ground, instead of the negative side like the rest of the caps.

Keep us informed, pics are always good! (Thanks for the pics you've already posted, I've not seen the inside of this particular model of Deluxe Reverb before)

Thanks,
vinyl


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Post subject: Re: Replacing filter caps
Posted: Fri Dec 19, 2014 2:14 am
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vinyl wrote:
This should be the schematic for your amp:

http://bmamps.com/Schematics/fender/deluxe_reverb_boost_schem.pdf

Besides the 16uF F&T caps, you'll need 5 25uF and 1 5uF cap and the 100uF 100V cap that stratele52 mentioned. Your best bet for the 25uF caps is Sprague, 25 or 50 V rating. 50 V would be a little better. F&T doesn't make 25uF single caps. For the 5uF, get the closest to 5 uF you can find, like a 8uF 150V Sprague.

Pay careful attention to the polarity of the bias supply cap, (100 uF, 100V cap) in second picture, the positive side will go to ground, instead of the negative side like the rest of the caps.

Keep us informed, pics are always good! (Thanks for the pics you've already posted, I've not seen the inside of this particular model of Deluxe Reverb before)

Thanks,
vinyl



+1


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Post subject: Re: Replacing filter caps
Posted: Fri Dec 19, 2014 3:55 am
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stratele52 wrote:
djwhitjr wrote:
...Are the Sprague Atoms that much better?
No .
I alway use F & T since Sprague are too expensive and not better .
...


+1, same here.

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---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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Post subject: Re: Replacing filter caps
Posted: Fri Dec 19, 2014 7:00 am
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Aspiring Musician
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Thanks guys! I'll be placing an order soon and will keep you posted on the progress once I start.


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Post subject: Re: Replacing filter caps
Posted: Fri Dec 19, 2014 7:24 am
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djwhitjr wrote:
Thanks guys! I'll be placing an order soon and will keep you posted on the progress once I start.



+1


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Post subject: Re: Replacing filter caps
Posted: Wed Dec 24, 2014 4:27 pm
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Is the 8uF (original 5uf) capacitor the far left cap circled in yellow? The markings on the cap are hard to read and I am new to reading schematics. If I am reading the schematic right, I see a 5uf capacitor coupled with a 100K resistor in the V5 tube circuit / vibrato input. This appears to match what I am seeing physically in the amp.
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Post subject: Re: Replacing filter caps
Posted: Wed Dec 24, 2014 6:30 pm
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Yes, the bypass cap on far left of your photo is OEM 5/50. I've used the Sprague 8/150 in this position. No problems.


Good luck! Keep us posted.

Oh yeah... Merry XMAS! :mrgreen:


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Post subject: Re: Replacing filter caps
Posted: Sat Dec 27, 2014 5:36 pm
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Success! New caps came in the mail today and were swapped with no problems. Pics below. The amp sounds a lot better! Think I am going to keep the speaker for now. :D

Now that the caps have been replaced do I need to re-bias the amp?

Image
Image
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Post subject: Re: Replacing filter caps
Posted: Sat Dec 27, 2014 5:37 pm
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Aspiring Musician
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Post subject: Re: Replacing filter caps
Posted: Sat Dec 27, 2014 6:30 pm
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Aspiring Musician
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DJ,

Good job.

The bias should be checked, do you have the knowledge and necessary equipment to do it? If so, post the results (plate voltage and bias current) here. It's important to measure both.

If not, say so and there will be advice given on how to measure it. There is more than one way, but using a bias probe is probably safest.

Regards,
vinyl


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Post subject: Re: Replacing filter caps
Posted: Sat Dec 27, 2014 7:08 pm
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Good job, indeed! Amp should now have a nice strong , clean tone.

:mrgreen: :D :mrgreen:


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