Please, don't get tangled up trying to replace amplifier protection fuses. They don't need changing because when you have the transformer tapping set for 240V and 240V mains applied, the amplifiers operate just as before. That's what tranformer tappings are there for.
You only have to change one ceramic slow-blow (T3A) fuse - 250V. Don't be tempted to mess with anything else if you can avoid it.
Here's an example, assuming yours was this size - easy enough to search the site.
CF06333CT/6/10 - MULTICOMP - FUSE, ANTISURGE, CERAMIC, 6A | element14 Australia
Note that it wasn't easy to find a ceramic cartridge type at only 3A rating - perhaps a glass type is OK at the lower current. Others may know more about appropriate choices.
You only have to change one ceramic slow-blow (T3A) fuse - 250V. Don't be tempted to mess with anything else if you can avoid it.
Here's an example, assuming yours was this size - easy enough to search the site.
CF06333CT/6/10 - MULTICOMP - FUSE, ANTISURGE, CERAMIC, 6A | element14 Australia
Note that it wasn't easy to find a ceramic cartridge type at only 3A rating - perhaps a glass type is OK at the lower current. Others may know more about appropriate choices.
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Well that would make my life easier.
So ignore the six amp protection fuses at the back and only replace one of the six 6A fuses at the front of the unit next to the transformer?
Am I understanding that correctly? Wouldn't the turn-on surge from the 240v blow the 120v fuses if I only replace one of them?
So ignore the six amp protection fuses at the back and only replace one of the six 6A fuses at the front of the unit next to the transformer?
Am I understanding that correctly? Wouldn't the turn-on surge from the 240v blow the 120v fuses if I only replace one of them?
Nope, you're not getting this - looks like my fault.
In post 6 you said "Just checked, the board label near the fuse and it specifies the current rating for a 240v as 3A, half the 120v rating as you said."
Well it seems no fuses have anything do with different supply current rating or the primary transformer side at all because as shown, the main fuses F901,2 (the only transformer protection) will be the same type on any correctly connected AC supply.
These fuses are located in the secondary AC supply leads to the rectifier for the +/-42V DC power rails, in both leads of the 29.5V main secondary AC windings. So they won't require changing for the reasons given already about the voltages of the secondary side of the transformer being just as before - as intended.
So after looking for something that wasn't there (and it's a worry to me why not), it seems you don't need to change any fuses at all.
I'm a bit suprised, so other comments are more than welcome, from my point of view anyway.
In post 6 you said "Just checked, the board label near the fuse and it specifies the current rating for a 240v as 3A, half the 120v rating as you said."
Well it seems no fuses have anything do with different supply current rating or the primary transformer side at all because as shown, the main fuses F901,2 (the only transformer protection) will be the same type on any correctly connected AC supply.
These fuses are located in the secondary AC supply leads to the rectifier for the +/-42V DC power rails, in both leads of the 29.5V main secondary AC windings. So they won't require changing for the reasons given already about the voltages of the secondary side of the transformer being just as before - as intended.
So after looking for something that wasn't there (and it's a worry to me why not), it seems you don't need to change any fuses at all.
I'm a bit suprised, so other comments are more than welcome, from my point of view anyway.
Yeah I got that wrong, sorry for the confusion. I read it as "T6 3A" rather than T6.3A.
The only difference between the current fuses and the ones recommended for 240v operation is the "T" prefix.
That's just because of the difference in coding between the US/Canada and the 230/240Vac world.
A product will have to comply to all standards, so the fuse markings have to be two-fold.
If I were to go to an electric goodies shop and ask for a 3 All-Glass fuse, they'd think I escaped from the loony bin.
T6.3A is a standard fuse type in 230/240Vac regions.
An individual is supposed to think for oneself whether a 5x20mm or a 6.3x32mm size is required.
(As we all know, Germans have labelling/cataloguing embedded in their genes. Their DIN thing was likely the first to come up with a system for fuses, adopted by the rest. T is for slow, F stands for Flink, which means rapid/fast, M for Mittel, aka average/regular. So the range goes TT < T < M < F < FF)
The S was likely added for regions which are unfamiliar with the T-code.
A 6 amp fuse is a common value in the UL/CSA system (UL is underwriters laboratories, CSA is Canadian standards association)
The fuses are at the secondary side of the transformer, so it makes no difference whether they are 125V or 250V types.
As it is not desirable that a US customer goes to a store, asking for 6A/250V fuses, the board also has a 6A 125V fuse printing.
In the end, the liability lawyers are satisfied, and folks who are unfamiliar with the difference in standards, wind up in the swamp.
A product will have to comply to all standards, so the fuse markings have to be two-fold.
If I were to go to an electric goodies shop and ask for a 3 All-Glass fuse, they'd think I escaped from the loony bin.
T6.3A is a standard fuse type in 230/240Vac regions.
An individual is supposed to think for oneself whether a 5x20mm or a 6.3x32mm size is required.
(As we all know, Germans have labelling/cataloguing embedded in their genes. Their DIN thing was likely the first to come up with a system for fuses, adopted by the rest. T is for slow, F stands for Flink, which means rapid/fast, M for Mittel, aka average/regular. So the range goes TT < T < M < F < FF)
The S was likely added for regions which are unfamiliar with the T-code.
A 6 amp fuse is a common value in the UL/CSA system (UL is underwriters laboratories, CSA is Canadian standards association)
The fuses are at the secondary side of the transformer, so it makes no difference whether they are 125V or 250V types.
As it is not desirable that a US customer goes to a store, asking for 6A/250V fuses, the board also has a 6A 125V fuse printing.
In the end, the liability lawyers are satisfied, and folks who are unfamiliar with the difference in standards, wind up in the swamp.
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That's interesting Jacco.
Is it common for amps to have no protection fuses on the primary side of the transformer?
Could a power surge damage the transformer?
Is it common for amps to have no protection fuses on the primary side of the transformer?
Could a power surge damage the transformer?
Not uncommon. For single phase up to a couple of amps it's not mandatory afaik.
In case of toroidals, the secondaries are on top of the primary winding(s), mechanically protect them.
With a mishap, it's commonly the secondaries which cause transformer trouble, fuse all of them individually and the primary winding is in the clear.
Without a main switch between the AC inlet and the transformer, the primary would have to be fused.
(transformers without a fuse on the primary usually have a built-in thermal fuse on the cold side)
In case of toroidals, the secondaries are on top of the primary winding(s), mechanically protect them.
With a mishap, it's commonly the secondaries which cause transformer trouble, fuse all of them individually and the primary winding is in the clear.
Without a main switch between the AC inlet and the transformer, the primary would have to be fused.
(transformers without a fuse on the primary usually have a built-in thermal fuse on the cold side)
Thanks for the info.
So now I just need to change the electrical plug.
The US plug is 2 pin with no earth? Most of our plugs here are 3 pin. What's that all about?
I was thinking of using this plug: Plug Top Hpm 10amp Grey Cd100lgy I/N 4330037 | Bunnings Warehouse
all good?
So now I just need to change the electrical plug.
The US plug is 2 pin with no earth? Most of our plugs here are 3 pin. What's that all about?
I was thinking of using this plug: Plug Top Hpm 10amp Grey Cd100lgy I/N 4330037 | Bunnings Warehouse
all good?
That's an economical solution but the preferred one would be to use a standard, 2-wire double insulated moulded plug and cord assembly, removed from a discarded appliance. The minimum rating will be 7.5A, so there won't be problems with current rating. As long as it is in good condition, the minimum 1.8m length should be plenty and it will outlast the Rotel amplifier. I usually have spare cords and dead appliances on hand but neighbours also dump their appliances - just ask.
The service manual doesn't show detail of the cord entry ferrule, called "AC cord stopper" but I assume it's a standard component that is removable and will clamp all similar double insulated power cords securely. Be certain to preserve the A (brown) and N (blue) polarity.
The service manual doesn't show detail of the cord entry ferrule, called "AC cord stopper" but I assume it's a standard component that is removable and will clamp all similar double insulated power cords securely. Be certain to preserve the A (brown) and N (blue) polarity.
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Hi Ian, the current cord type is different to the one you’ve shown so I’m not sure the ferrule will accept it. I’ll have to check when I get home.
The cord also runs alongside the heat sink under the case and is wrapped in some kind of heat proof cloth tape.
Lastly the connection to the board is in a cramped spot and I fear ill stuff up the soldering trying to get it in there.
I understand its not ideal but I’d much rather just wire up a new plug on the end. Is there a safety risk using the old cord?
Thanks
The cord also runs alongside the heat sink under the case and is wrapped in some kind of heat proof cloth tape.
Lastly the connection to the board is in a cramped spot and I fear ill stuff up the soldering trying to get it in there.
I understand its not ideal but I’d much rather just wire up a new plug on the end. Is there a safety risk using the old cord?
Thanks
FYI, many wiring standards have changed with globalisation and hyperactive safety regulators in recent times. North America now also has 3 pin (earthed) outlets and appliances where appropriate and we in Oz now have more 2 pin (unearthed) appliances and plugs. We have always had unearthed appliances too, but it is misleading to fit 3 pin plugs to everything, since users then assume the device is earthed.
No comment about the stupid habit these 2 pin round plugs have of falling out of their sockets or how easily the flimsy insulated pins now bend and break!
No comment about the stupid habit these 2 pin round plugs have of falling out of their sockets or how easily the flimsy insulated pins now bend and break!
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OMG, surely you know how to put a plug on an appliance.
2 Pin = Live & Neutral
3 Pin = Live, Neutral and Earth
To wire a two wire cord into a 3 pin plug you just connect Brown to Live and Blue to Neutral.
I'm surprised it's only two wire.
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OMG, do you have the reading and comprehension skills of a five year old?
I know, but thanks for your wisdom anyway.
Read my post again - I was merely expressing my surprise that the cord was only two wire.
lol
Not necessarily but be aware that the socket's cord clamp ferrule likely won't secure the thin cable. Never rely on the screw connections or wire entrapment path to clamp the cord.
The plugs are usually designed for 3 wire 10A flex.- note the flex size spec. Careless tugging on the cord(we all do this) could become dangerous. Still, we've lived with such problems for decades with those crappy moulded plugs - just keep kids and over-enthusiastic cleaning people well away from them.
I'm dragging this out because in recycling one sees what DIY people - even your friends really get up to and it's often horrifying. I don't like leaving even no-brainer tasks like plug replacement to some guys who for vanity or laziness, just don't read or understand labels let alone the basics of electrical safety. They still fit plugs, though.
How rude - Yes I can read and write and I try to be helpful.
Your post stated what's a 3 pin plug all about.
Your post stated what's a 3 pin plug all about.
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Well O/T but...
By contrast, Brits seem to enjoy activities like badger watching or "twitching" - a mind boggling creature obsession indeed. BBC Twitchers A Very British Obsession - YouTube
I don't think I've seen many 'roos in 20 years except as roadkill in the central desert regions or the subject of culling with some very nasty high power weapons on rural properties. Few, other than city folk, who don't have to suffer them, would consider keeping them happy. If you'd had to defend yourself when a 2m 'big red' thought you were a threat and set about shredding you, you might feel the same way. Ask a rural North American what they think about their cute and cuddly bears even.
By contrast, Brits seem to enjoy activities like badger watching or "twitching" - a mind boggling creature obsession indeed. BBC Twitchers A Very British Obsession - YouTube
Ian,
as a consolation, I fear it has turned a global irritation.
A month ago, I assumed the battery of my cell phone had reached retirement age, turned out that the 2-pin plug of the charger autonomously decided to crawl out of the socket, vertically.
(to my surprise, Skippy tasted rather good)
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