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AC30CC2 won't power on... how should I troubleshoot?

andyothling

Member
Messages
718
Hey guys... I'm getting ready to sell my AC30CC2 and of course it only starts to have issues now...

Out of the blue it decided to stop powering up. I tried all the obvious fixes... tried a different outlet, different power cable, checked the fuse (it was fine). So where should I go from here? I know getting into the chassis is a pain, so I'd like to have a plan before I go in. Are there any common problems I should be looking for? Also, what is the best way to test for a bad tube?

Thanks for your help...
 

teleamp

Senior Member
Messages
3,478
Are you getting power to the fuse? Time to break out the multi-meter... if in doubt, take it to a tech.
 

andyothling

Member
Messages
718
Don't have a multi-meter...

I'm just trying to avoid taking it to a tech and finding out it's something simple like a bad tube.
 

teleamp

Senior Member
Messages
3,478
If it won't power up with a good fuse, your going to have to use some means of testing for voltage, if you can't, you'll need to take it to a tech... Sorry to be a downer, but your situation is what it is.
 

VaughnC

Silver Supporting Member
Messages
18,399
Test the fuse with an ohm meter or, if you don't have a meter, try a new fuse...sometimes a fuse can visually look good but be electrically bad. However, if the fuse is bad, something caused that to happen as they seldom just go bad on their own. So, if you don't know you're way around inside an amp its best to have a qualified tech look at it as there's lethal voltage in there....even unplugged.

I'm not familiar with that particular amp but the only tube that would prevent it from powering up would be the rectifier tube (if the amp has one). Do the tube filaments light up?
 

darth_vader

Member
Messages
315
My AC30 blew a rectifier tube, taking out the mains fuse, HT fuse, and low voltage power supply in the process.

Make sure you've checked both the fuses on the back of the amp (one is in the round enclosure that's opened with a screwdriver, the other is located directly beneath the socket for the power lead.

When you power it up, is the green power lamp lighting up at all? How about the heaters on the tubes (you may have to open up the chassis to see the tubes). If the lamp and heaters are coming up, then it could be either the HT fuse or the low voltage.

Note that there are also two fuses located internally on one of the PCBs. However, I wouldn't recommend going looking for those unless you have some experience working on amps, as the capacitors can hold a lot of charge and you really don't want to get zapped by one of those.
 

Cirrus

Member
Messages
2,429
I might be missing something, but haven't you tried a different rectifier tube / quad of power tubes? that'd definitely be very high on my list. It's a valve amp, and if they don't work the valves are the first culprit.
 

teleguido

Member
Messages
446
Seems like 95% of the time that one of the AC30CC amps won't power on it's because of the rectifier tube. I am NOT an amp tech, but I own an AC30CCH. This is what I would do:

1. Remove the chassis (it's really not very hard, just be careful not to strip the screws). Check ALL of the fuses, as there is more than one. Replace them if they are blown.

2. Replace the rectifier tube. Many folks have good things to say about the JJ rectifier for these amps.

3. Power the amp on with the Standby switch already on (so that sound would be coming out of the amp) and NEVER USE THE STANDBY SWITCH ever again. Just leave it in the "on" position.

There's a wealth of information about why you shouldn't use the Standby switch on these amps, just google "ac30cc2 standby switch" and you should be able to get an understanding of it. Hope that helps!

DISCLAIMER: amps contain lethal voltages and can kill you. I am not an expert, and if this advice makes you uncomfortable you should take your amp to a tech.
 




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