[iyonix-support] Re: Some Guidance Required Please

  • From: John Ballance <jwb@xxxxxxxxxx>
  • To: iyonix-support@xxxxxxxxxxxxx
  • Date: Sat, 30 Apr 2011 07:50:54 +0100


On 29/04/2011 21:14, Julie wrote:

On 29 Apr, John Ballance<jwb@xxxxxxxxxx>  wrote:

Please may I make a serious suggestion - as the power supplies to the
motherboard are critical in that they have little margin for error, ANY
attempt to muck around with the 5v supply after it has been regulated by
the powersupply will lead to grief. Basically, DONT!

Agreed!


Jim's suggestion - better power supply -  is really the only valid answer.
Oh, and BTW, the 'indicator' of the 5v power supply voltage being
between 5.06 and 5.08v is just that. On the supplies originally fitted,
the supply would hold this voltage reliably when working correctly.
Towards the end of its life, the regulation became far less effective,
and that was INDICATED by the change in the 5v rail.

I have never been able to understand why the voltage is this critical.
Neither does my OH. We are both electronics engineers. Back in the
good old days, TTL would tolerate 4.75 - 5.25V, 7V absolute max.
CMOS could run anywhere between 3V and 18V. (I know that many of the
more recent ICs run at 3.3V.) Why is the Iyonix so sensitive?
with apologies for seeming to rant - For Heavens Sake.. we are talking about the voltage as indicated on a voltmeter.. this is the DC (around 0Hz) value of the voltage. This being off target in the original power supplies INDICATED that other aspects of the supply had degraded .. In other words, the NOISE or ripple (> 0 Hz) at the supply output had SIGNIFICANTLY increased. That would be the real problem I believe.
AND BEAR IN MIND, these original power supplies were sourced almost entirely in late 2002 and early 2003.. i.e. around 8 years ago. I wonder how many far east PCs of late 2002 would still be running on original power supplies by now - relatively few?
Seriously though, the interrelationship of all the different supply voltages within the iyo, derived from this 5v supply, was always a juggling act. Additionally most of the power supplies we were able to source at the time were reluctant to provide a stable output voltage at the relatively small load (for the time) that our friend consumed.
I forget what proportion of supply variants we had to reject as unpredictable in the development phases of the iyo. 

John



Stop press! Just announced - Price Promise
# The Utility Warehouse Price Promise means you can benefit from: The UK's cheapest Home Phone 
# The UK's cheapest Home Phone and Broadband bundle
# The UK's cheapest Mobile tariffs
# The UK's cheapest standard Gas and Electricity

Or they will give you back Double the Difference!

Charges, terms and conditions apply. For full details of
the Utility Warehouse Price Promise see http://www.ucallusave.co.uk
<http://www.ucallusave.co.uk>

Intrigued? Call me

John Ballance C.Eng MIET - jwb@xxxxxxxxxx - 07976 295923

Julie (and Tony)



---
To alter your preferences or leave the group,
visit //www.freelists.org/list/iyonix-support
Other info via //www.freelists.org/webpage/iyonix-support
List-related queries to iyonix-support-moderators@xxxxxxxxxxxxx

Other related posts:

  1. Home
  2. iyonix-support
  3. Archive
  4. 04-2011