I had a Vibrochamp in reported dead. Sure enough, the wire from the tip of the fuseholder somehow came loose. Further visual found all the Ck were exploded and leaky. These are 22uF/50V , I've never seen that before. I replaced the four of them and the feedback resistor, as it had drifted from 2700 to 270. Really... red-violet-red. Under certain settings, when dimed, it would oscillate at 41kHz. I replaced the commie power tube with a Hammond 6V6 so the oscillation is dead and the tone opened up also.
Success aside, the burst open cathode caps thing freaks me out. I've never heard of that, much less seen it.
Vibrochamp anomaly
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Vibrochamp anomaly
Tube junkie that aspires to become a tri-state bidirectional buss driver.
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Stevem
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Re: Vibrochamp anomaly
I have seen the bypass caps blow a end cap out , but never the whole body , but I guess it s possible since I have seen bigger electrolytics go the whole way, plus the fact that they have been replaced already as Fender never used 50 volt preamp by pass caps, they where 25 volt!
I would say they must be very cheap caps that cost .15 cent!
How do the plate load and cathode resistors test out?
I would say they must be very cheap caps that cost .15 cent!
How do the plate load and cathode resistors test out?
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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MeanMrMustard
- Posts: 102
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- Location: Texas
Re: Vibrochamp anomaly
Pics?
Re: Vibrochamp anomaly
Heres a pic after the repairs, the amp is back with its owner, in a Deluxe cab with a Weber 4 Ohm 12F150. I'll post a pic of the caps when I get back in the shop.
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Tube junkie that aspires to become a tri-state bidirectional buss driver.
Re: Vibrochamp anomaly
Did you check the filter caps as well?TUBEDUDE wrote: ↑Thu Jul 26, 2018 7:20 am I had a Vibrochamp in reported dead. Sure enough, the wire from the tip of the fuseholder somehow came loose. Further visual found all the Ck were exploded and leaky. These are 22uF/50V , I've never seen that before. I replaced the four of them and the feedback resistor, as it had drifted from 2700 to 270. Really... red-violet-red. Under certain settings, when dimed, it would oscillate at 41kHz. I replaced the commie power tube with a Hammond 6V6 so the oscillation is dead and the tone opened up also.
Success aside, the burst open cathode caps thing freaks me out. I've never heard of that, much less seen it.
Its quite normal for electrolytic caps to die by about 20 years of age. The dielectric deteriorates, especially if the amp has sat on the shelf for any length of time. The exploded Ck plainly showed that. However, the filter caps also need checking and replacing if they're the same age (which chances are, they are)
He who dies with the most tubes... wins
Re: Vibrochamp anomaly
The filter caps are fine. All the resistors and caps are within spec. less the parts I replaced. I'm well aware of the limitations of the various components. That's why I endeavor to use foil, film or anything but eletrolytic.
Tube junkie that aspires to become a tri-state bidirectional buss driver.