Amp gurus. Need help. 5153 issue

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SFW

SFW

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So last night during practice we were in the middle of a song when suddenly my amp went silent. I turned around to find that the pilot light was on, but all of the power tunes were dark. I checked the fuse on the back of the amp and it was still intact. Took the chassis out of the shell and metered the internal fuse and it was blown. I'm going to try to find another fuse today and see if the amp will fire up. I know that usually when I fuse blows it is a sign of something else being not right in the amp. The power tubes are only a few months old. So I'm hoping that they haven't gone out. Although if they had, I would have expected the fuse on the back of the amp to blow. Not the internal fuse...? Any assistance trouble shooting this with me would be greatly appreciated. Thanks guys!!
 
SFW":1bm9p6ls said:
So last night during practice we were in the middle of a song when suddenly my amp went silent. I turned around to find that the pilot light was on, but all of the power tunes were dark. I checked the fuse on the back of the amp and it was still intact. Took the chassis out of the shell and metered the internal fuse and it was blown. I'm going to try to find another fuse today and see if the amp will fire up. I know that usually when I fuse blows it is a sign of something else being not right in the amp. The power tubes are only a few months old. So I'm hoping that they haven't gone out. Although if they had, I would have expected the fuse on the back of the amp to blow. Not the internal fuse...? Any assistance trouble shooting this with me would be greatly appreciated. Thanks guys!!
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Is it one of the smaller sized ones? 1 milliamperes I think, I had one of those blow a couple years ago. I had an EQ in the loop and it was set very high and poof, I changed that fuse and it never happened again. I don't think it was related to the EQ really but it happened while I had the EQ on and I was testing some settings at the same time.

Just my experience with a blown internal fuse. Now I'm having foot switch issues :( It changes channels randomly and stays stuck between two channels :confused:

Good luck.
 
I have a TC G-Major 2 in the loop. I have the gain on the TC at 0dB. So it's the same volume when the unit is in the loop and the amp is when there is nothing in the loop. I hope that's not causing the problem. I can't live without delay. Lol.
 
SFW":svvdyjqe said:
Although if they had, I would have expected the fuse on the back of the amp to blow. Not the internal fuse...? Any assistance trouble shooting this with me would be greatly appreciated. Thanks guys!!
Click to expand...
Actually, the internal fuse is typically the HT fuse (high tension) that protects the rest of the amp from the heater circuit. I'm not an EE or an amp tech so I'm sure someone will chime in and confirm or correct. But you're right, it usually does mean something is up. All you can really do is just buy the new fuze (buy several) and see what happens. Monitor your tubes closely for red-plating etc. If the fuse blows again, then consider taking it in.

If you want to take it a step further then get a bias probe and run it on each tube. That's what I would do anyway.
 
i had one that the internal fuse holder was bad on and it caused the fuse to blow.
 
Ok. So the fuse says 6C12A250V on it. Could someone explain this code to me? I deal with fuses all day long at work, but those usually say things like 10A 250V.
 
SFW":zhbcvd86 said:
Ok. So the fuse says 6C12A250V on it. Could someone explain this code to me? I deal with fuses all day long at work, but those usually say things like 10A 250V.
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It looks like it is embedded right in part number just like you are used to. :dunno:

12 amps 250 volts
 
Yeah. That's what I was thinking as well. Just trying to make sure I get the correct value.
 
If it is marked as F1 that is the heater fuse. I would check your tubes with an ohm meter if you have one for a shorted heater.

Power tubes pin 2 to 7
preamp tubes pins 4 to 9 and 5 to 9

If you replaced the power tubes recently I would check there, just make sure that they are all reading close. This can help save you a few fuses.
 
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