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PA & Amps How hard can it be?

Zugzwang

Member
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545
I've lost a channel on my venerable Rotel RA-02 amp. Definitely not speakers, cables or the ports. So... if it's a fuse, how much might it cost to purchase the necessaries - voltmeters etc - and how hard will it be for an absolute beginner (but more or less methodical and rational) to locate and replace the blown fuse, if fingers crossed that's the problem?
 

Halfers

Finger Flapper
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1,959
Take a look at this thread on the same amp and issue. Might help.

 
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Zugzwang

Zugzwang

Member
Messages
545
Thanks guys. That’s not like you @Colin the Bear - you normally recommend studying 4 hours a day for 20 years.…
I have read that @Halfers - it gave me hope I could avoid driving to Exeter and then having it sent to Worthing (?!) for a week. And I’ve got the diagrams @Targa - though I’d be happier if the thing they illustrate was the size of a football pitch.
Is anyone used to the insides of old hi-fi ?
 

Halfers

Finger Flapper
Subscriber
Messages
1,959
Thanks guys. That’s not like you @Colin the Bear - you normally recommend studying 4 hours a day for 20 years.…
I have read that @Halfers - it gave me hope I could avoid driving to Exeter and then having it sent to Worthing (?!) for a week. And I’ve got the diagrams @Targa - though I’d be happier if the thing they illustrate was the size of a football pitch.
Is anyone used to the insides of old hi-fi ?
I took my old Arcam amp apart once. Lots of blobby bits and silver lines...does that help? :p
 

Ivan

Undecided
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Messages
7,238
I took my old Arcam amp apart once. Lots of blobby bits and silver lines...does that help? :p
My Circa 1993 Arcam went through a fuse blowing phase on one channel

I didn't know what the matter was, opened case, found blown 1amp fuse. Easy as

If you don't find a blown fuse inside then you could scout about for misshappen capacitors. There's lots on t'internet about those... very cheap to buy but need some unsoldering, resoldering action to replace
 

rhysonsax

Well-Known Member
Messages
4,125
I've got the Rotel RA-01 which seems to be the same as the RA-02 but without remote control. It hasn't started blowing fuses yet, but these days I do most of my listening with headphones.

I wouldn't have any qualms about taking off the case and having a rummage around inside, once the power is properly isolated. Fuses will be designed for easy replacement.

Good luck and let us know how it goes.

Rhys
 
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Zugzwang

Zugzwang

Member
Messages
545
Hurrah, I shall buy the necessaries and report back - the RA is old enough to have real, three-dimensional bits inside, so fingers crossed.
 

randulo

Playing alto 2 ⅓ years
Subscriber
Messages
4,124
Hurrah, I shall buy the necessaries and report back - the RA is old enough to have real, three-dimensional bits inside, so fingers crossed.
Carefully note where the screws go! If the fuse is blown, it might be visible, but some are not. If there are other parts, like resistors or condensers, sometimes they're burned or exhibit other visible damage.
Screen Shot 2020-05-24 at 07.49.47.png

The fuse should be in a clip arrangement that makes it easy to remove.
 

Colin the Bear

Well-Known Member
Messages
12,781
In my experience a good tech will sort things for less than the tools cost. I'd rather spend my time practicing than breathing solder smoke. ;)
 

rhysonsax

Well-Known Member
Messages
4,125
In my experience a good tech will sort things for less than the tools cost. I'd rather spend my time practicing than breathing solder smoke. ;)
I generally agree, but if it's just a blown fuse that needs to be replaced it is the work of five minutes and no solder or tools other than a screwdriver, mainly down to removing and replacing the case cover.

But then you may wonder why that fuse blew in the first place .... I would have a good look for overheated or damaged components and if there's nothing obvious, change the blown fuse one time myself. Second time it would be off to a specialist, or these days maybe look for a new amp.

Rhys
 

Chris98

Senior Member
Messages
1,115
If a fuse has blown, it's usually blown for a reason, it's there as a safety device. This is especially true when it's within the box and you need to remove the casework to access it.


If you do open it up and have a route around remember capacitors can hold charge even when disconnected.
 

Targa

Among the pigeons
Subscriber
Messages
8,817
A fuse can blow simply because it's old so with nothing obviously wrong change it and see if it blows again.
Of course you could always do it 'professionally' and simply wrap the blown fuse in the silver paper from your fag packet and stick back in again.
 

rhysonsax

Well-Known Member
Messages
4,125
A fuse can blow simply because it's old so with nothing obviously wrong change it and see if it blows again.
Of course you could always do it 'professionally' and simply wrap the blown fuse in the silver paper from your fag packet and stick back in again.
Ah, that reminds me of when I was the official "electrical person" in the sixth form at boarding school, presumably because I was good at physics and wasn't yet dead. When something electrical blew I went to look in the fuse box (probably 1920s vintage) and found that one of the fuses had been replaced by a six inch nail.

Happy days ...

Rhys

PS It wasn't the six inch nail that had blown, in case you were wondering.
 

Vetinari

Senior Member
Messages
1,193
Not all fuses are the same type, even if size and current rating are the same. The various types are..
Slow blow
Quick blow
Anti surge
Normal
The differences are usually designated by a letter code but last time I worked on these things was 20 yrs ago and I can't remember all the details.
 
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