Official dumb question thread..

AKSA · « **Reply #20 on:** 31 Jan 2005, 06:50 am »

Martin,

You certainly can extend TP1 and TP2 for test purposes and there will be no effect on sonics. However, it's dangerous; should these leads short to ground, you can say goodbye to your output stage!

However, you'd be better advised to buy a couple of clip on leads for your DMM, $3 each at Jaycar/DS, so you can slip them onto the transistor emitters, switch on, then measure off directly.

When you are finished, switch off the amp, disconnect, and you are done.

You could run a single earth return for your speakers, but I don't advise it. Earth return currents for all three channels will be mixed in the one wire; this is known to cause tiny intermodulations which is the reason bi-wiring sounds better.

A better arrangement is to have separate earth returns for each speaker.

Cheers,

Hugh

soitstarts · « **Reply #21 on:** 31 Jan 2005, 06:53 am »

Thanks Hugh...
thats why I put it in the dumb question thread. Time to go and think of some more...

soitstarts · « **Reply #22 on:** 7 Feb 2005, 01:36 am »

All righty, I've been thinking again..

If I put the star Earth on the back panel and ran a cable from the PCB earth to the new star earth will this be a problem?

Also, I noticed that the AKSA case has an aluminium front panel and a steel back panel. Is there a performance reason for this or is it all down to economics.

Thanks. Again..

Martin.

AKSA · « **Reply #23 on:** 7 Feb 2005, 02:05 am »

HI Martin,

The star earth is best left on the power supply pcb, but you certainly can run a wire to an insulated binding post on the rear panel for earthing other components. No problem at all - this will do the trick nicely.

Rear panel is steel for strength, and front panel is Al for thickness and ease of drilling. Ain't life simple??

Cheers,

Hugh

soitstarts · « **Reply #24 on:** 11 Feb 2005, 12:53 pm »

Hello again

I am getting closer on Mark II and am starting to work on my wiring paths..

I am going to run all my power wires under the powr PCB to the terminals on the Amp PCBs and was thinking of running my earths to the Component side of the Power PCB for simplicity. Is there interference issues with running my Earths between the Power Caps or am I better off creating a new star earth some where else that I can run 1 earth from my PCB?
Hope I made that clear enough. Thanks,

Martin

SamL · « **Reply #25 on:** 13 Feb 2005, 09:52 pm »

How long should a blue 3mm LED light last? One of the LED on my aksa100 stopped working and another is starting to blink. They are around 6 months old and there's burn mark on one of the lead. I think it is call anode, the one with the longer lead. That's the lead the resistor connected to.
Don't think I've apply too much current to the LED as I am running them very dim. Can't remember the resistor value and I am guessing it is around 270R.
I wonder if me applying too much glue around the lead restricted the LED ability to self-cool. Any idea?
The replacement works without any problem but I would like find out why as I don't want to change LED every 6 months.

TIA,
Sam

AKSA · « **Reply #26 on:** 13 Feb 2005, 09:59 pm »

Martin,

Beautiful work, very nice metal work. All al welded? Nice job.......

Sam,

Blue LEDs should last about twenty years. I have a couple on a N+ AKSA 55W in my home that are a couple of years old, and the amps have been turned on just about all that time. If you are running no more than say 0.2mA through them, they will be bright and last well, but if you have failures after 6 months there is something wrong; either in the product, or in the way you are soldering the leads, or in the mounting. Can't say unless I see it close up........

BTW, dissipation in these critters is very low. With 2.2 volts across it, and 0.2mA (a typical current for the BLEDs), you have a dissipation of 0.44mW, which might just raise the junction temperature over ambient by about one tenth of a degree!!

Cheers,

Hugh

soitstarts · « **Reply #27 on:** 13 Mar 2005, 11:28 pm »

Me agian..
The instructions say to use a 5 amp fuse for the 240V supply. Since I have 3 channels, do I use a 7.5 amp fuse? Or am I oversimplifying things, again...

Thanks,
Martin.

Greg Erskine · « **Reply #28 on:** 14 Mar 2005, 12:30 am »

hi soitstarts,

For safety's sake, I like to use the smallest fuse that works, so I would use the 5 amp fuse (or smaller) and see how it goes. If it fails, increase the rating a little and seek more advice from Hugh.

IMO your logic is correct, 7.5 amp fuse should be the maximum size to use.

AKSA · « **Reply #29 on:** 14 Mar 2005, 01:27 am »

Martin,

Greg's advice is good. Use the 5A fuse; it should be sufficient, because the combined current load for three channels is unlikely to exceed two channels of stereo because speech almost never occurs when music is playing loud!

Cheers,

Hugh