How could the top of a 4B be opened ..

KKG · « **on:** 24 Nov 2003, 01:34 pm »

.. for cleaning? The screw-driver/key-slot is square shaped and I've not come accross a tool that could fit it. Will opening up the top for a little vacuum cleaning negate the warranty?

TIA
KKG

gazza982 · « **Reply #1 on:** 24 Nov 2003, 02:00 pm »

You will need a Roberston No 1 screwdriver to remove the screws. There are no seals so as long as you are careful there shouldn't be a problem.

afblaster · « **Reply #2 on:** 25 Nov 2003, 12:09 pm »

Be careful! The screws are very tight - Bryston must use a hi-torque air tool to tighten these. Make sure the screwdriver is inserted fully into the square hole with enough pressure so that it doesn't 'cam' itself out when you attempt to undo the screw, which will result in damage to the screw head. If the screw won't undo, tap the top of the screwdriver ( while it's inserted in the screw head) before re-trying. I had this problem with an SP1.7 which I needed to get into, all the screws were too tight to remove without using this method.

KKG · « **Reply #3 on:** 26 Nov 2003, 11:25 am »

Thank you for your kind responses, gentlemen

gazza982, is the Roberston #1 screwdriver a regular flat tip type? If I am unable to procure the said brand of scredriver, will some other brand do? What would be the size #? I measured the diagonal ends of the slot and it read 3mm, am I right or is it 4mm?

Will this exercise affect the warranty at all?

Thank you again.

KKG

James Tanner · « **Reply #4 on:** 26 Nov 2003, 12:48 pm »

HI KKG,

It will not void the warranty to open the top but it is really not necessary.
The dust will not affect the performance and most amps get dirty because they use fans to draw air over the circuitry - we don't use fans of course.
The srew driver is called a Robertson Green Handle ( there are Red, Black and Yellow as well) They are a Canadian invention and considered to be the worlds best "screw".

james

KKG · « **Reply #5 on:** 26 Nov 2003, 01:47 pm »

Hello James

It's an honour to recieve a response from your goodself.

I live in Singapore and the room my system is in is not air-conditioned as it is cool enough for my comfort; only a ceiling fan, to circulate the air, is employed.

My previous amp, an Adcom GFA 535 (no internal fan), used to get pretty dusty on the inside and I note that it used to get pretty warm to touch. However, after each cleaning, the amp runs much cooler.

The cleaning involved dusting the circuit board with a soft bristle brush (Chinese Caligraphy type) and a small noozle adapter on the domestic vacuum cleaner's flexi-noozle.

The 4BST, as is, is pretty warm to the touch (much warmer then the Adcom but then the Adcom was just a 60W/ch unit). As it sits on the floor, between the speakers, my concerns is that dust may get in through the vents and settle on the board thus inhibiting heat from dessipating for optimum performance. Though Neil Young reckons rust never sleeps, I think this should extend to dust as well.

Would there be an avenue to prevent dust from entering the amp, some type of ligh netting screen perhaps? Your comments would be much appreciated.

Regards
KKG

James Tanner · « **Reply #6 on:** 26 Nov 2003, 02:20 pm »

Hi KKG,

No sir the honour is all mine.
I suppose given your circumstances that a cleaning certainly would not hurt but the Bryston amps will run warmer than most because the transistors are bias high.
I can tell you that we have been selling 4B's into Singapore for over 30 years and so far we have not had any issuses with overheating.

james

nicolasb · « **Reply #7 on:** 26 Nov 2003, 11:53 pm »

Just make sure you are slightly less of an idiot than I am by not switching on a power amp that is sitting on thick carpet and wondering why it goes into thermal overload.