Hi Bernard, I'm still catching up from last week...... did you get your replacement tube ? and if so everything up to snuff ?
Opinions on Tube Amp Problem?
- Thread starter Bernard
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Hi Bernard, I'm still catching up from last week...... did you get your replacement tube ? and if so everything up to snuff ?
tonepub
Senior Member
Personally, I'd rather be safe than sorry...
Hopefully it's just a tube or worst case a resistor. I had a Manley eat the resistor and a couple of caps once from a bad tube.
Ugh.
And that's why I keep thinking about going tubeless!
Hopefully it's just a tube or worst case a resistor. I had a Manley eat the resistor and a couple of caps once from a bad tube.
Ugh.
And that's why I keep thinking about going tubeless!
User211
Well-known member
On the other hand, if I had my amps checked every time a tube went over the years I have been using them, the bill would have been silly. And the inconvenience factor high.
Components that have gone often look it. If you have some basic component knowledge i.e. you know what a cap or a resistor looks like, you could always have a look inside the amp. When small caps go, they can look bloated or expanded. Resistors may look burnt. A multimeter can also help here.
If you do this before you put the new tube in, be sure all the big reservoir caps have discharged. That means leaving the amp disconnected and off for 30 minutes to be really safe. Then just open her up...
Bernard, be careful. If you don't leave time for the caps to discharge, you could be in for a nasty jolt. You can always short them to discharge, but my brother once did that to an old valve TV, made a mess of it, and got thrown across the room. I therefore do not recommend it!
Components that have gone often look it. If you have some basic component knowledge i.e. you know what a cap or a resistor looks like, you could always have a look inside the amp. When small caps go, they can look bloated or expanded. Resistors may look burnt. A multimeter can also help here.
If you do this before you put the new tube in, be sure all the big reservoir caps have discharged. That means leaving the amp disconnected and off for 30 minutes to be really safe. Then just open her up...
Bernard, be careful. If you don't leave time for the caps to discharge, you could be in for a nasty jolt. You can always short them to discharge, but my brother once did that to an old valve TV, made a mess of it, and got thrown across the room. I therefore do not recommend it!
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Bernard
Well-known member
I got my replacement tube yesterday. Before inserting it I put in a set of old tubes that I know work fine, powered up the unit, and let it warm up a bit. Nothing untoward happened. With the replacement tube in (and the others I normally use), it biased perfectly (I did not have to touch the pot). I have not had a chance to listen to it yet.
Justin, I have not had too many tubes go bad on me, but agree that would be cost-prohibitive to have the amp checked out every time (I do not have deep pockets). BTW I do know better than to discharge a cap by shorting it out,
Justin, I have not had too many tubes go bad on me, but agree that would be cost-prohibitive to have the amp checked out every time (I do not have deep pockets). BTW I do know better than to discharge a cap by shorting it out,
slowGEEZR
Well-known member
Off topic, but when I was in the military in Okinawa back in '74, I used to work on 20,000 watt transmitters. The caps in them were larger than a car battery and the only way to discharge them was via a shorting wad, as they would actually charge themselves!
In a high school electronics class I accidentally shorted out a high value cap with my arm. I still shake just thinking about it. A big spark and I was half way across the room. I learned my lesson that day!
MiTT
Super User
At least you learned the lesson!
I used to work for a high speed machine vision company doing part inspection in real time as the components were moving down a conveyor at about 90ppm. The only way we could manage those kinds of speeds was to utilize a very high rate xenon stobe array to "freeze" the parts as they moved along. The strobe required a massive bank of capacitors to refresh repeatedly. One day I was working in the lab and one of the Electircal Engineer's I worked with had taken the cover off of the system camera so that he could do some adjustments in real time while the system was live (Oh boy, here it comes). So he has his head over the camera and is reaching in with a small screw driver and BAM, he shorts across the high voltage leads and it literally sends him flying back across the room! I run over to him and say "Mark, are you OK!?!?" It was like a friggin' cartoon I swear, he says "I'm good!" through a grimmice and shakes his head real fast like he's trying to get the cobwebs out. I think the only thing that was missing was a couple of puffs of smoke coming out of his ears!
BUT WAIT...
So then he walks right back over to the camera and puts his face right back down into it, inserts his screwdriver again AND BBAAMM, THE EXACT SAME THING HAPPENS!!!
I just about wet myself!!!
:ROFL:
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The triumph of education over common sense:music:
Bernard
Well-known member
Dave, I fired up the amp today with the replacement tube; works great :music: In my experience, most of the time when a tube dies the solution is to just replace it. Guess I have been lucky with no resistors getting taken out.
