6B-SST Faulty:FAO James

gingellr · « **on:** 6 Oct 2007, 06:04 pm »

Hello James,

I have only had my 6B-SST now for a day and it has now stopped working on one channel.

I was using it for a couple of hours this morning with no problem, turned it off for a while.
When i turned it on again only 2 of the channels (centre and right) came on the left channel seems totally dead no led comes on at all!

Is there anything i can do to reset this or is the unit faulty?

This is my first bryston and one of the reasons for getting one was for relaibilty so obviously quite dissapointed it has failed on its first day.

If there is nothing i can do what is the procedure for getting this sorted. I am in the UK about 30mins form the PMC factory.

Thanks

Richard

James Tanner · « **Reply #1 on:** 6 Oct 2007, 06:15 pm »

HI Richard,

If there is no light then I think it may be an output device.

Give Andy a call at PMC.
andy@promonitor.co.uk

I am sorry for the problem - usually the 6B is very reliable. Is it a brand new unit?

I just noticed you had said earlier that the 6B was running hot. Have Andy check the BIAS settings on all the channels for you as well.

james

gingellr · « **Reply #2 on:** 6 Oct 2007, 07:30 pm »

Hi James,

Thanks for your reply.

After rechecking it i would not say it was running hot as such, I just noticed it was hotter than the 4B. It was only warm really.

If it is the ouput device as you say, will just the amp module be replaced? If so will a new one sent and fitted at pmc, or will the whole unit have to be sent back to yourselves or will i keep the faulty unit until a new one is sent out?

It was about a month before i received it after i ordered it so ideally would prefer not to be with out an amp for that length of time again, so if it has to be sent back would pmc have an amp they could loan me while mine is being sorted?

What do you think the turn around time will be?

thanks

Richard

James Tanner · « **Reply #3 on:** 6 Oct 2007, 09:44 pm »

Hi Richard,

If it is just the output device it could be fixed very quickly.
I have emailed Andy so lets see what he has to say.

james

gingellr · « **Reply #4 on:** 6 Oct 2007, 10:12 pm »

Hi James,

Thanks for that.

Any idea what could have caused it, do these failures happen often or have i just been really unlucky, as i know you test all units for 100 hours.

Richard

James Tanner · « **Reply #5 on:** 6 Oct 2007, 10:47 pm »

There is always a chance of what we call ' infant failure' - devices fail early - but it is rare.

Usually when an output goes it is caused by the output section seeing a short - speaker wires crossed, speaker crossover problem etc. or something causing the input of the amplifier to ossilate due to the output of your preamp or source component.

james

gingellr · « **Reply #6 on:** 6 Oct 2007, 11:03 pm »

It must be "infant failure" unfortunately then.

I can assure you no speaker wires were crossed, and it was working perfectly last night and for most of the day today.
It failed when turning it back on after I was out.

The speakers i am using are PMC OB1's which have not caused a problem with my previous amp and are now working on the 2 remaining working channels on the 6b so it is unlikely to be a crossover problem.

Richard

gingellr · « **Reply #7 on:** 8 Oct 2007, 11:48 am »

Sorry James just noticed i did not answer one of your questions.

Yes it is a brand new unit, it arrived from Bryston on Thursday of last week at PMC.

I have now spoken to PMC and i am taking it in to them tomorrow for repair.

Richard

James Tanner · « **Reply #8 on:** 8 Oct 2007, 12:56 pm »

Hi Richard,

OK great - please let me know how you make out.
I emailed Ceri the Bryston repair technician and he will take care of things for you tomorrow.

james

gingellr · « **Reply #9 on:** 8 Oct 2007, 03:01 pm »

Hi James,

Thanks for that, it was Ceri I was speaking to this morning, he was very helpful.

Excuse my ignorance on this, but as i understand you use matched transistors on the 3 amps.
So will these not be matched now if just one transistor is being replaced?

Thanks

Richard

James Tanner · « **Reply #10 on:** 8 Oct 2007, 03:06 pm »

Yes it will be matched as you never replace just one transisitor - you always replace both and match them.

james

James Tanner · « **Reply #11 on:** 10 Oct 2007, 03:11 pm »

Hi Richard,

Spoke with PMC and apparently the problem was a wire not properly soldered on the 6B channel that failed- my apology on this.

james

gingellr · « **Reply #12 on:** 10 Oct 2007, 10:02 pm »

Hi James,

I Picked up the 6B again this afternoon. All channels are running now.

I was surprised to hear the problem was down to a connection that had been missed and was not soldered, but i guess these things happen as they are all soldered by hand i understand. Anyway i was glad it was that rather than a transistor failure.

Apparently the unit was actually running too cold also, so he adjusted the bias to make it run hotter.
The coolest amp at idle is now 106F and the hottest at idle is 113F I assume these temps. are normal? (although alot hotter than the 4B i borrowed)

Is there an issue if the amp runs too cool then?
Could you also tell me the min and max temps that the amp should reach for normal operation?

Thanks for your help and input on this.

Looking forward to listening to the sound quality i will now get with the new amp.

Richard

gingellr · « **Reply #13 on:** 11 Oct 2007, 06:56 pm »

Hello James,

I am not happy at all with the amp, i am thinking about asking for a full refund.

I have just turned the amp on for the first time today, not even put any sound through it.
After about five minutes of it being turned on the center amp led has turned yellow and the amp itself is red hot and is now muted.

This really is not good enough i dont think, especailly as it has just got back from being adjusted and checked at pmc.

Just a bit fed up with spending so much money on an amp that i have not been able to use since i have had it!

Richard

gingellr · « **Reply #14 on:** 12 Oct 2007, 12:14 am »

Hello James,

Here is an update:

I let the amp cool down a little, turned it back on and the channel was green and working again.
Left it on for a few hours and using it with no problem.

Then i turned it off to let it cool right down to about room temperature, turned it back on again with no speakers or input connected to that channel, again it overheated within 10mins.
Turned it off again until it cooled down a little and turned back on all was ok and running at normal temp.

So it seems to be only an issue when powering on from cold, once its cut out it then works ok.

This particular channel i have been using all week before it went to pmc with no problems. Which may just be a coincidence.

As you can imagine i am quite frustrated with this now, to have 2 faults on 2 seperate channels on a brand new amp. So it appears i have a substandard unit and I have lost confidence in bryston equipment at the moment.

I do not think this is acceptable at this level and quality of amp. I assume and hope this is not the norm else you would not give such a good warrenty.

So i would like a completly new 6B and to keep the faulty one until it arrives then swap them out.
Could you let me know if this is possible?

If you would rather chat about this on email rather than this forum i am happpy to do so.

Richard

*edit* Just to confirm it is everytime so far, just switched it on again from room temp after 5 mins it cut off with yellow led, this time i did not turn it off manually, it cooled on its own then led went green and amp kept dropping in temp until normal temp was reached.

James Tanner · « **Reply #15 on:** 15 Oct 2007, 12:32 pm »

Hi Richard,

Sorry I have not responded to this earlier. I was at the Hi Fi Show in Denver since Thursday.

Has anyone at Bryston or PMC contacted you?

james

gingellr · « **Reply #16 on:** 15 Oct 2007, 12:52 pm »

Hi James,

No problem, i guessed you were away for a few days.

I emailed PMC and coppied it to your email address also.

PMC are arranging with Bryston to send me out a new 6B and that i can keep the faulty one until it arrives.

PMC also said they have only experinced thermal runaway like this a couple of times in 10 years.

Having said that, It has now also happend on the left amp twice over the weekend, but it is still everytime on the center amp. It seems to happen on the left amp if i use it straight away rather than let it get to normal temperature before i do.

It is a little worrying that it has happening on 2 amps, could it be a bad batch of amp modules/components do you think?

Richard

James Tanner · « **Reply #17 on:** 15 Oct 2007, 12:57 pm »

Hi Richard,

I think PMC may have re-adjusted the Bias incorrectly. I am on it.

james

gingellr · « **Reply #18 on:** 9 Nov 2007, 01:52 pm »

Hi James,

Just to let you know, my new replacement 6B was deliverd this week and everything is working with no problems now.

Thanks for your help.

Richard

James Tanner · « **Reply #19 on:** 9 Nov 2007, 03:14 pm »

Quote from: gingellr on 9 Nov 2007, 01:52 pm

Hi James,

Just to let you know, my new replacement 6B was deliverd this week and everything is working with no problems now.

Thanks for your help.

Richard

No Sir thanks for your patience and understanding.

james