Tube Amp Theater How to repair fix Fender Princeton filter capacitor
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- เผยแพร่เมื่อ 29 พ.ค. 2016
- This little brown face Fender Princeton came to me via mail from a fellow vintage amp lover. It had a bad hum and oscillation. Very evident while monitoring with an oscilloscope. Problem turned out to be a leaky filter capacitor. I changed it with a newer style chassis mount cap. The repair went well. Hope you enjoy.
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Quick diagnosis; I found myself doing the same thing when you checked the amp, great way of keeping your skills topped up, very nice demonstration Terry.
KOOOO-UHHHHL! Today, the Ungar is a "SNOZZASAURUS"! Me like. And the FILTER CAP has become the "SNOZZERAMUS"! Reminds me of "The Prince and the Pauper".
You're TOO FUN! Thanks for the vids.
Nice! That output transformer is huge!
love the Ghoulardi reference! ! Keep up the great videos!
That is a really neat trick for checking caps! I've never seen that before. Glad to know I don't need one of those expensive ESR meters, despite how groovy and quick that would be - I think switching from DC to AC on the meter is also pretty darn quick!
Thanks man. Yep, approx 90% of all amp repairs can be done with a basic multi-meter. Glad you like.
Nicely done!
great vid...thx!!
I built a princeton reverb clone based on the AA1164. I added a grid bias pot and re-worked the bias board. I set the bias pot to give me -34 VDC per the drawing. Should I have measured plate voltage and current?
Doc to D Future🤓 Ur D Man !!! Hands down ....
Mr. D-Lab, do leaky filter caps cause that sort of distortion that I like to call "snaggletooth" distortion - that's most prominent when you strike two dissonant lower bass notes, or just two close bass notes - just a nasty cat growling that sort of lingers and fades in and out then dissipates - does that sound familiar?
so.. I replaced my caps with a ce mfg. how ling should they be on the variac, before its ready ?
Intrigued by that "audio test set" you used. Looks like a D-lab special. Probably a simple network of resistors and switches. Maybe do a video about it sometime?
th-cam.com/video/Ej5-TvgXLXQ/w-d-xo.html Here it is!
Thanks for doing this video. At five minutes 45 seconds you use your multimeter on 2 megaohm setting to determine cap leakage. The first two sections have no measurement (Meaning there is a resistance at least higher than two mega ohms present) but then the third section shows 1.2 ohms. Is that correct? Or is it 1.2 megaohms? When you say "see that?" are you saying that 1.2 ohms is the indicator of leakage? 1.2 mega ohms might still not be... Also, it would be normal for the number on the multimeter to start climbing from 0 (On the scale of two mega ohms that is) wouldn't it? As the charge builds in the capacitor?
Thanks again. Great video.
Love your amp video's.. interested in your Pro opinion on caps. Does the "brand" of the cap have any significance on the tone/sound of the amp? I know some purist call for certain brands of caps to use as replacements. Does it really make any difference in what I hear from the amp?
So, if I have the caps on my 100% original 1974 Fender Twin replaced with new caps, will the tone sound different from brand to brand with whatever you use for the job? noticed you used rubycon.. thanks...
Hello, Thank you my friend. I enjoy making the videos, especially after a few glasses of wine. For power supply filter caps, brand is not critical. I have used Rubycon's for years, no complaints/returns, very reliable. The name brands, like Mallory are more than double the cost. Have never noted a performance difference. Best thing is to get the old leaky caps out of your amp. They drag down your high voltage/degrading sound. Hope this helps, stay tuned, TD
I don't see anything wrong with putting the new style of filter caps. They are easy to replace later
i am seeing swinging ac voltage from filter can up to 50V. why is this? please help
Hey hey hey..over dey! Marshalls are made in Parma?
Why did you go with a bigger value negative bias cap? And does that effect the sound? And is using a variac necessary when first powering up an amp with a new filter cap(s)?
Hello John, I always use 33uf caps in the negative bias circuit when building amps. The 33 is a slight increase from the stock 25's, no changes in sound. The 5Y3 tube allows for a ramp start-up, so the new caps are not shocked. The new cap is rated for 500vdc rather than the stock 450. Turned out well. I still have to verify a few other things, then it ships out. TD
curious to know where you get that multi-cap from.
CE distribution out of Pheonix, AZ.
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You said that filter cap was about $10. Where do you get it?
CE distribution in AZ sells them
Turn blue? I preferred "stay sick". Are you from N.E. Ohio?
I'm in Battle Creek, Mi. Watched the Ghoul as a kid " Creature feature"
um from Paaaaaarrmaaa over day
What a Hack!
Why not wire out the old filter cap and use three modern radial caps? If you want to get artsy-fartsy, you can scoop the guts out of the old one and stuff the new ones into it. A little hot glue and Bob's your uncle.
Turn Blue
Stay Sick
You purple knif