Power Amp Help/Advice Needed

[ovlov854]

I have a Sirius (Gamut) D100 power amp which is a dual mono single mosfet model
Two nights ago whilst warming the system up prior to listening all power went off and by the time I got a torch the room was filling with acrid smoke.
I took the lid off the amp and found one of the transformers insulation was burnt and discoloured and stank!!!
The power caps appear to be unmarked.
Some pics below
https://i.imgur.com/xNN6ohj.jpg
https://i.imgur.com/Ww37PIB.jpg
https://i.imgur.com/MqO2dTZ.jpg
https://i.imgur.com/GfrKAyB.jpg
https://i.imgur.com/PmpRkHU.jpg
https://i.imgur.com/44xYMm6.jpg
https://i.imgur.com/w6NB0Gq.jpg
https://i.imgur.com/lxSJ0S2.jpg
https://i.imgur.com/cpO4vcg.jpg

Some of these are with flash and some normal.
What are members opinion when something like this happens?
With a transformer gone would repair be a cost effective option,presumably with dual mono both transformers would need to be replaced??
Any engineers opinion welcome

BTW how do I test my speakers to see if there is any damage there? There was nothing playing and my RDC tripped everything out PDQ
HELP

[Sherwood]

What are members opinion when something like this happens?

Put new batteries in your smoke detectors! :idea:

Seriously though, shouldn't an expensive and powerful amp like that have some built in safety features like thermal cutout?


Geoff

[walpurgis]

Speak to Alan (Firebottle), he's near you. He can probably advise and may repair too. If it was me, I'd replace both transformers with matched new items.

[struth]

assuming a short somewhere so will need looked at before a new tx is fitted..surprised if no fuse was fitted inside. but its another reminder that you need to be in attendance when gear is on.

[Haselsh1]

Wouldn't an event like this have drawn a huge current from the mains..? If so then why no fuse or other protection device..? I truly feel for you, this is the kind of thing no one wants to face with any kind of gear let alone very expensive gear.

[ovlov854]

What are members opinion when something like this happens?

Put new batteries in your smoke detectors! :idea:

Seriously though, shouldn't an expensive and powerful amp like that have some built in safety features like thermal cutout?


Geoff


assuming a short somewhere so will need looked at before a new tx is fitted..surprised if no fuse was fitted inside. but its another reminder that you need to be in attendance when gear is on.


Wouldn't an event like this have drawn a huge current from the mains..? If so then why no fuse or other protection device..? I truly feel for you, this is the kind of thing no one wants to face with any kind of gear let alone very expensive gear.

I too am surprised by the lack of fuse on the case, but reading the Owners Guide it mentions some serious circuit protection which I do not understand which I think is aimed at muting the output signal.
Thank the Lord for my domestic RDC

[antonio]

Sorry to hear this, should never happen to an amp of this quality. Inform the importer.

[Firebottle]

Hi Martin,
I am very surprised there isn't an internal fuse. I can take a look and repair it with pleasure, it sounds to me as if a rectifier could have failed and put a short or partial short on the transformer.

[nonuffin]

It's not uncommon for mains transformers to have shorted turns and burn out, so probably a new one will get the power amp working once more.

[ovlov854]

I too am surprised by the lack of fuse on the case, but reading the Owners Guide it mentions some serious circuit protection which I do not understand which I think is aimed at muting the output signal.
Thank the Lord for my domestic RDC

Further update:-
I was perplexed that I could not find a fuse on the Sirius so I consulted the blurb and yes I found a 2.5 slow blow fuse so neat that I had missed it
The blurb said that the fuse would go when power consumption reaches 600 watts
The fuse is intact but the RDC tripped everything out before the fuse went

The moral of the story is make sure you have a decent RDC
Some folks say that an RDC can have a negative effect on hifi sound but there are models that are better than others (consult Uncle Russ in the North) !!!!

[goraman]

It is not funny when this kind of thing happens, the only time something like this has happened to me was a toroidal transformer in a new DAC.
You will want to check all psu capacitors and the rectifiers, I would fit slightly stronger transformers in there if it where an option. I am told the higher VA the better.
Some of the best audio grade are used in older copy machines and medical equipment Switzerland and other Scandinavian country's.
If they are made in china forget it.

[reddish75]

Hi Martin,
I am very surprised there isn't an internal fuse. I can take a look and repair it with pleasure, it sounds to me as if a rectifier could have failed and put a short or partial short on the transformer.

I'd go with this, I've seen a couple of A1000's suffer the same fate, they seem to broil the rectifier caps as well.

As a side note get rid of those gold wima caps they also have a high failure rate.

[ovlov854]

Buggerbuggerbuggerbugger !

Only been able to connect up my loan amp last night and it appears to have damaged one speaker which now crackles and distorts sound
Going to turn into an expensive Xmas

[Light Dependant Resistor]

Thats a strange result. Has the speaker any fuses ? Have you access to a multimeter ?

With amp off and no speaker leads connected Check resistance ohms of each speaker measuring across the sockets
should be between 3.5 and 10 ohms

Then check continuity of the speaker leads end to end.
see if you can identify which speaker driver is faulty
Post up some images... lets see if we can get your hifi running again

[ovlov854]

Thats a strange result. Has the speaker any fuses ? Have you access to a multimeter ?

With amp off and no speaker leads connected Check resistance ohms of each speaker measuring across the sockets
should be between 3.5 and 10 ohms

Then check continuity of the speaker leads end to end.
see if you can identify which speaker driver is faulty
Post up some images... lets see if we can get your hifi running again

Hi Images
https://i.imgur.com/m7s7ofB.jpg
https://i.imgur.com/d6gxkaM.jpg
https://i.imgur.com/dbSbYs1.jpg
https://i.imgur.com/x850MWj.jpg

Speakers are WB Actor 2.5 way ie midrange and tweeter connected to same terminal.
Checked resistance across terminals both speakers 6ohm and 7ohm accross bass.
Applied 9v battery to individual drivers ...allpopped in and out.
Could not discern anything from tweeter....not sure I should???
On playing it will play a CD through but then only misbehaves when warm
suspect tweeter??

[walpurgis]

I wouldn't put 9v DC through a tweeter.

[ovlov854]

I wouldn't put 9v DC through a tweeter.

This was advice from the Tech Dept at WB.
They said that the tweeter would not react as midrange and tweeter are connected to same set of terminals

[George47]

Simple test. Keep amp off, then GENTLY spread your hand out over the cone on the bass/mid units and gently push them in and release. Not too far. If the bass or mid unit have problems then instead of allowing you to gently push the cone gently in they will grate. Be careful as you are not trying to stress them but more trying to determine if the coils have melted, If they have then they will grate. If not it could be tweeters.

[walpurgis]

That may or may not tell you anything. Some perfectly good speakers will grate if the cones are moved by hand simply because of the tight gap/coil tolerances. try it on Lowther drive units and you'll see what I mean. It is difficult to push a cone in a truly linear way by hand.

Grating coils are usually just misaligned. Overheated coils can be perfectly sound electrically, but bind due to bubbled lacquer having swelled. Also, they can become non-concentric (oval), this will cause binding too. Melted (blown) coils may not foul the coil gap.

[sq225917]

That's bloody awful build quality, power wires going through holes in casework with no grommets and such like.

[WESTLOWER]

That's bloody awful build quality, power wires going through holes in casework with no grommets and such like.

You'll notice the OP's heading, requesting for help or advice, not sure he was looking for a negative slagging off of the amp!:scratch:

[ovlov854]

That's bloody awful build quality, power wires going through holes in casework with no grommets and such like.


You'll notice the OP's heading, requesting for help or advice, not sure he was looking for a negative slagging off of the amp!:scratch:

A number of people have commented about the poor build quality of this amp including guys who have actually worked on them.
They are right but it sounds great (to my ears)

HOWEVER the good news is that FIREBOTTLE (superstar of this Parish) has sussed it out and repaired and serviced it. So its up and running again
So much appreciation to Alan

[Edward]

A number of people have commented about the poor build quality of this amp including guys who have actually worked on them.
They are right but it sounds great (to my ears)

HOWEVER the good news is that FIREBOTTLE (superstar of this Parish) has sussed it out and repaired and serviced it. So its up and running again
So much appreciation to Alan

What's the news on your speakers? Good that the amp fixed.

[sq225917]

You'll be looking forward to dealing with Wilson Benesch's excellent service dept...

[ovlov854]

What's the news on your speakers? Good that the amp fixed.


You'll be looking forward to dealing with Wilson Benesch's excellent service dept...

Well this is the curious bit, As reported the right speaker made strange sounds and so I swapped the speakers and the same speaker made the same sound on the other channel; so that would indicate the speaker yes??
Further checks using different speakers and a different amp could not reproduce the fault. We thought that the first loan amp was at fault and misbehaved once warmed up.
My Actors seem to be working as they should but have only been in use for a couple of CD s at a time.
So I live in hope
Thanks to all who made suggestions

[Hypnotist]

Is all still well Martin ? odd the speaker now seems to be ok

[ovlov854]

Is all still well Martin ? odd the speaker now seems to be ok

Yes all seems to be as it should (furiously clutching a piece of wood)