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XTC POW1 Fuse blow

Bairnstorm

Bairnstorm

pfm Member
I have a XTC POW1 power amp which goes back to about 2000.

I have owned it for about 10 years and it has been flawless.

Tonight after about 5 minutes of being on it stopped suddenly and the sound and front light went out. No fuss no bangs just one minute fine, next dead.

I took out the fuse which is 5mm x 200mm from RS checked it and it is dead.

Firstly does anyone know if this should be a quick blow or a slow blow?

This has never happened with this amp before (unlike my old valve amp!).

Should I be concerned and is there anything to look out for?

Sorry this is a basic question.
 
If that is the AC Mains input fuse, replace with a 'T' rated fuse of sim amp value e.g. 'time delay' - these are required, in such a use in any amplifier, to not blow on the inrush current of the power transformer at turn-on.

As far as your second point - no, just because the fuse finally died is no reason to be concerned. It's been stressed every time you've turned the amp on, and is at least 10yrs old to your knowledge -and possibly, the original fitment. They do just eventually die under everyday use.

If the fuse blew every time the amp was turned on, then you should be concerned (although that too is usually easily diagnosed, and fixed).

HTH


PS: what use rating do you require? Take a really close look at the fuse and one endcap will likely be embossed with the rating eg.g. ' T 5 A 250VAC' or similar. If so, and you can't find a convenient source, I likely have a spare I'll happily post to you gratis.
 
I checked the fuse and it reads T10A H250 so 10A and T rated as you say.

There is a great electrical shop in Ealing so will pop in tomorrow. They normally have some weird and wonderful fuses. If not RS are still selling them.

Thanks for putting my mind at rest as the amp has been the most fuss free and reliable piece of kit I have owned apart from a Technics SUA900which is still going strong. Thanks also for putting it in language I could understand!
 
10 Amps? Are you sure? That’s a very, very big fuse for an amp!

PS For comparison my Pass Aleph 3 class A amp has a 2A fuse!
 
T10A H250
T- trage/time delay
H - High breaking capacity
250 - 250v

10amp high rating same rating of my 900wpc monos
 
Tony L said:
10 Amps? Are you sure? That’s a very, very big fuse for an amp!

PS For comparison my Pass Aleph 3 class A amp has a 2A fuse!
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Nelson traditionally includes an NTC thermistor in the AC Mains input side to add several tens-of-ohms here to limit inrush current, until it (the NTC, not the whole amplifier!) gets up to running temp. Which is ... hot. A very slow/soft-start.

That in turn allows very 'close' selection of Mains fuse capacity vs. peak actual draw - hence, say, the 2A rating you see :)
 
Plus, the POW 1 has a massive transformer. Weird design - big va transformer and lower value smoothing caps. Sounds good though.
 
What’s the story behind XTC? I remember them appearing; big chunky things with rack handles and a very glossy finish, I remember people liking them (don’t think I ever heard one, though I’ve certainly seen them in dealers). Then they vanished without trace. Who designed them? Were they anything before, did they go onto anything later? I just know nothing about them.
 
A bit if history here from me, when I ran a thread on both PRE & POW 1 I bought. Long since sold at huge profit, but great amps.
 
Well that went well. Bought two fuses from City Radio in Ealing and they both died within 30 seconds! I suppose I can deduce from that it is a bit more serious.

If anyone knows someone decent around West London or if Chris Bryant still services these much appreciated.

Tony as far as I know XTC were designed by Chris Bryant and were the short lived upmarket brand for Orelle and built in Middlesex.

It is very heavy, well put together and until the last 24 hours has been absolutely bullet proof. Mine is black gloss with handles front and back.

Soundwise it is muscular with good tone and a big spacious sound. Over 150 watts into 8 ohm and doubles to over 300 watts in to 4.

It drives my KEF 3.2's much better than a VTLST85 valve power I had. Bass is much deeper and sound stage bigger. The VTL had a bit more natural and delicate treble with acoustic instruments but this seems to have 2 more octaves in the bass region.

I think it is much underrated but have only lesser MF's to compare it with (A3) and the odd Croft, Icon Audio and stuff. I'm using it with a VTL 2.5 valve pre.
 
Bairnstorm said:
Well that went well. Bought two fuses from City Radio in Ealing and they both died within 30 seconds! I suppose I can deduce from that it is a bit more serious.

If anyone knows someone decent around West London or if Chris Bryant still services these much appreciated.

Tony as far as I know XTC were designed by Chris Bryant and were the short lived upmarket brand for Orelle and built in Middlesex.

It is very heavy, well put together and until the last 24 hours has been absolutely bullet proof. Mine is black gloss with handles front and back.

Soundwise it is muscular with good tone and a big spacious sound. Over 150 watts into 8 ohm and doubles to over 300 watts in to 4.

It drives my KEF 3.2's much better than a VTLST85 valve power I had. Bass is much deeper and sound stage bigger. The VTL had a bit more natural and delicate treble with acoustic instruments but this seems to have 2 more octaves in the bass region.

I think it is much underrated but have only lesser MF's to compare it with (A3) and the odd Croft, Icon Audio and stuff. I'm using it with a VTL 2.5 valve pre.
Click to expand...

It's a 4 channel amp - have you bridged them (key on back) or just using one channel? If only one channel, you may find disconnecting power supply rails to currently connected channels, and using the other outputs, will bring it back to life. This assumes output transistors have failed. It could of course be something in the PSU itself. Good luck - worth repairing.
 
If it was working fine and now just blows AC mains input fuses I would start by checking the PSU rectifier diodes (or packaged Bridge rectifier,if thatls what it has- pretty likely). A failed diode there is a classic source of this annoyance.
 
Dowser - I use it bridged in stereo mode with little connectors in. I had it biwired because Noel Keywood and everybody else said it sounded better. Tried it single wire and to me it sounded more powerful and generally better. I am in the minority I am sure.

It has been working brilliantly over many years so something has gone mad inside.

Martin I may open it up tomorrow to look if there is anything obvious. I can't believe it is anything serious and have been recommended a couple of local fixers.

I feel a fraud being on the DIY section as changing a plug and testing a fuse on a multimeter is my limit. Last time I replaced a tweeter my wife soldered it.

Thanks for the help so far.
 
Then most likely, as Martin said, a PSU problem - hopefully just a diode junction and quite easy to fix - good luck!
 
Bairnstorm said:
I feel a fraud being on the DIY section as changing a plug and testing a fuse on a multimeter is my limit. Last time I replaced a tweeter my wife soldered it.
Click to expand...

No!
NO!
Of course you belong here!
and -
I hope you'll find the many, well-informed and helpful members you'll find here in DIY are all-about & wholly-in-favour of - mutual support, and at every level: because we all started somewhere similar. Welcome!
 
Some internal pics. Can't see any internal shockers and it has VdH wiring!

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Just as an update. I have spoken to my repair guy and it is the transformer that has gone. Yes that massive bloody thing in the middle. He found the manufacturer who is based in Glasgow but they have gone out of business.

He is looking at other options but it is not a cheap repair.

Ever come across this?. The amp is 20+ years old so it feels a bit of a heartbreaker. Not what I was expecting.
 
I bought a second hand Arcam bottom range amp once to repair it. The chip was trashed, but it wasnt until I tried it out after repair that it was obvious that the thermal fuse, deep inside the transformer had been blown so it was trash.
 
Bairnstorm said:
Just as an update. I have spoken to my repair guy and it is the transformer that has gone. Yes that massive bloody thing in the middle. He found the manufacturer who is based in Glasgow but they have gone out of business.

He is looking at other options but it is not a cheap repair.

Ever come across this?. The amp is 20+ years old so it feels a bit of a heartbreaker. Not what I was expecting.
Click to expand...

To have the transformer go is a rare thing. I do wonder why unless it is obvious (scorch marks from a pinched winding from the way it was mounted, or similar.)

No, a replacement will not be cheap!

Given the nature of the beast it could be worth approaching one of the various good independent transformer winders in the UK make you a custom one to match as closely as is reasonable (if your guy has not already)
 
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