CRACK-LE......(silence)

Boohoo, I just switched my amp (Copland CTA401 valve integrated) from CD to phono without turning the volume down, and I got a loud 'crack' and a couple of splutters....then silence. Nowt from any of my 3 sources.
I didn't have anything playing on the turntable, but have noticed before when selecting phono (or RIAA a it's labelled on this amp) that I tend to get a 'whump' or similar sound if the vol isn't turned down.

No strange smells or puffs of smoke, speakers look visually fine and although the crack was pretty loud I don't think it was terminally loud. All valves still light up in the amp.

I don't have a spare amp or speakers at the mo' to find out what I've blown, but if anyone has any suggestions then I'd be glad to hear them!

????????!!!!!?????????

 

Does the amp have a safety cut out?
Try unplugging it for 5 minutes, then try again.
A long shot but it may work.

 

Just tried it again, having left it long enough for it to be cold to the touch (at least 10 - 15mins, and still nothing. I'll check the fuse at the back....

 

My power amps take about 15min minimum to come back after a cut out. They wait to be completely stone cold. A desk fan helps speed things up though!

 

OK, I'll leave it a good while, I'll find something else to do to occupy my mind for a bit, stop me from fretting, ha ha. Thanks for the help BTW.

P.S. fuse OK, but it's a mains fuse so nothing to do with the problem.

 

Well, having failed to keep my mind off the broken amp, I decided to take it's lid off instead!

I have had a look around to see if there's anything visually wrong with it and have found a couple of internal fuses, one of which looks suspiciously blown! It says 'T.630MA' on the circuit board and 1A 250v on the fuse.

So, with a bit of luck this is the culprit, and replacement will cure all my woes. Fingers crossed.

I'm off down the shops....

 

I am pretty sure this is the culprit...

 

Ah, well, you might be guilty of being as hasty as me!

My friendly electrician who happens to be a the end of my road supplied me with a shiny new 1A fuse, which I popped into place with a happy heart, reconnected all the appropriate cables, and....guess what?

Small but bright flash, shiny new fuse is now useless old blown fuse, and silence reigns supreme in my living room.

Hmm, and that was the last 1A fuse the leccy had. Maybe it was an unlucky fuse. In any case, I'll have to wait until tomorrow until I do anything else now, but if anyone has more ideas, please feel free....

 

Let's hope it's just the fuse.

I once had a cassete deck that all of a sudden refused to work, I've changed the fuse and tried all possible voodoo things, never opened the box though. I never touched it for 2 years then and only pushed the button once to demoinstrate to a friend that bloody thing is dead. It switched on as if nothing happened and worked perfectly since. I do not mean that you need to wait for 2 years though )

 

On my home made amp, I recently went through 10 x 0.5A and about 5 x 1A before upgrading D) to a 2.5A fuse, which seems to be fine so far.

 

You may need to find an anti surge, or slow blow fuse for this application. Your amp will take a very short but large current surge whilst all of the Capacitors charge up and the transformer cores energise.
I would disconnect everything from the amp so that there is less chance of either in input, or output from another component causing the fault.

Anti surge fuses often have what looks like a sping at one end of the fuse wire when you look throug the glass.

Good luck...

 

I couldn't resist another go so went down the shop again armed with the latest advice. This time I bought a 630MA fuse (that the board states), and a slow blow 800MA fuse.

630MA went the same way as the 1A fuses.

800MA slow blow......wehey! We have music!

What a relief! I couldn't afford an expensive repair right now so am ecstatic to have got it working, thanks for your help everyone, and fingers crossed (again) that it stays working!! In any case, I'm stocking up with a few spare anti surge / slow blow fuses from now on, ha ha.

 

great - what a result!!

 

Just for future reference, the giveaway is the 'T' in 'T.630MA'.

F = fast blow (normal)

T = time delay blow

and 630MA means 630 milliamps as you have already figured out.

 

Surely something caused the fuse to blow in the first place - do you know what that is?

The new fuse may just be a sticking plaster for a broken leg!

 

That's valve amps for you.. Work of the devil (Not Bub, obviously!)
My Lumleys used to do the same, for no apparent reason.
That's why I went heavy duty solid state!

 

Ah yes, but hopefully not; now that technobear has explained to me that the 'T' = time delay (which was what was printed on the circuit board) and the amp was fitted with a normal fuse, perhaps I can deduce that the normal fuse couldn't cope with the sudden surge (of me switching from line level to phono with vol turned up) and blew, whereas now that it has a slow blow fuse that can cope with the brief surges.

I guess the original fuse must have blown in the past for there to be an incorrect one in there, but as long as it's an infrequent event, I can live with it.

That's what I'm praying for anyhoo....only time will tell.

 

Slow blow fuse - good idea! I change my bulbs every week, is there a fuse in the switch?

 

Change you light bulbs over to energy saving flourescent lamps. I got sick and tired of changing light bulbs in my house every week, Since replacing them all with Energy bulbs a few weeks ago I've not replaced any. They are so cheap these days too, even if i don't get the full 5 or 6 years lfe out of them as advertised I'dsettle for 2 or 3 years, we'll see....

La toilette;

Don't forget that you've still got a 800ma fuse in there, i'd change it for the correct rating - just in case....

 

How the hell can you need to change light bulbs every week?

Do you turn them on and off all the time? We must change about 3 bulbs a year and thats the normal ones!