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Trace Elliot RAH300SMX blown fuse

F

fish bulb

Jul 20, 2009
16
0
#1
I finally fixed my Trace Elliot amp by replacing a blown capacitor and two resistors and it sounded amazing! I can't thank BassmanPaul enough for all of his help.

So that's the good news, but the bad news is that last night my brother was playing his Marshall half stack guitar amp on the same UPS (essentially a battery backup) as the bass amp and it overloaded it and the power dipped then cut out completely right in the middle of us playing. I tried turning it on this morning and it made a medium-loud sound as i hit the switch (on standby of course) and then the lights cut out acting as if there was no power plugged in.

I checked the "Mains Fuse" and sure enough it was blown. I replaced it with one of the same rating (6.3A, 250V) thinking that it would solve the problem. WRONG. Turned it on and right away it blew just like last time.


I did some research and i found 2 possibilities for causes.

1) Faulty pre-amp tube. This was my first initial thought but would that cause the fuse to blow when it's in standby? Also i looked at it and it appears to be completely fine although i'm not sure what it would look like if it was blown.

2) Blown internal fuses. I found 2 small circular socketed fuses marked "F1" and "F2" marked "T 1A 250V ac" as shown in the image linked below.
http://www.imageslim.com/images/img_4a7b4b9907dfe.jpg

I pulled them out but there no indication whether or not it has blown or not.


So, should i try and replace the valve and see if it works? Most likely i'll just blow another fuse (i have 3 spares at the moment). Or should i replace the smaller onboard fuses if i can find replacements?

Sorry for the detail but i figured i'd provide as much information as possible.

Thanks in advance!

P.S. I'm expecting many "take it to a licensed tech right away before you mess it up even more" replies and i do have a tech in mind if it isn't as simple as a blown fuse or replacing a valve/tube.

EDIT: I have since replaced the Bipolar Bear in the amp and works beautifully. Nothing else was problematic, only the old power board.
 
#2
Why on earth would you try to play through a UPS. It's not powerful enough to run a guitar stack and a bass amp. You could well have blown the UPS too. You've certainly damaged your Trace again! The tube will not make the power fuse blow. Blown outputs will. This I suspect is your problem.

Paul
 
#3
Yes i know i shouldn't play it through a UPS and i hate myself for making that mistake. I had absolutely no idea that the surge protector was plugged into the UPS at the time.

What do you mean by outputs? I'm clearly not well educated on amps and sorry for the unintellectual question. Would replacing the power section i.e. Bipolar Bear fix this issue?
 
#5
Funny thing about the whole situation is that i contacted British Audio Service about my other problem to get a replacement power section because they're site said they were out. After a week of not hearing back from them i went ahead and bought the replacement parts for $10 that i thought had a very slim chance of fixing the problem. About 10 minutes after paying for them i got an email saying that they just found one more power section so i decided to buy that as well just in case somebody buys it before me since the parts probably wouldn't work.

Turns out the parts actually fixed the problem and i was thinking about contacting BAS about returning the board (the package wasn't even opened so i'm hoping it wouldn't be a problem) but maybe i'll need it after all.
 
#6
Yes I think you will. You're the second person I've heard of who tried this with similar results. You simply cannot run a high power amp via a UPS. They have, at best, 1500VA capacity. If you have a 300W amp it's going to draw at least double that. Add a Marshall stack and you have a disaster on your hands.

In this business you HAVE to know just what you are plugging into. That is at home, at rehearsal or at the gig. You have to be aware of everything that can go wrong and take steps to avoid them.

Paul
 
#7
Don't worry, i've learned many lessons recently that will definitely stick with me.

Is there any way to check and make sure that replacing the bipolar bear will fix the problem but more importantly won't be damaged if something else is problematic?

I'd hate to replace that board and have it fry just because there is something else wrong.
 
#9
Hi,

sorry to drag up an old thread but I have a Vtype AH300 head at home gathering dust. I had a repair guy look at it and he said the power section was blown, he'd talked to TE about a replacement and there was no guaruntee that a new power section wouldnt blow either.

Does anyone know of any major issues with the 300w Bipolar power amp on these heads? and is there a permanent fix? sorry if the answers are already on the forum but I couldnt find anything using the searches.

Ive got an AH300SMX and a Hartke head as back ups but Id LOVE to get teh v-type up and running again. It sounded great for the 2-3 months I was gigging with it.
 
#10
You should have started a fresh thread IMO. From what I've found that 300W is actually 150W @ 4Ω. Fixing the amp is a fairly simple change out of the output devices. I was very disappointed in the engineering of my amp. Cooling was very poor as was the method they used for thermal tracking. Post a photo of the amps inside chassis.

Paul
 
#11
Thanks Paul. If it is 150w, it's got a lot of guts @4ohm. I ran it with 2x10 & 1x15 cabs.
I will try and get a photo tonight and then start a new thread. thanks for the reply.

Ive been told by my repair guy that it is an easy fix, but that the replacement parts do not really 'fix' the underlying issue as to why they fail.
 

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