Emax

11.9 is fine remember it has a tolerance of + or - 10% its usually the currant side is the problem or ripple from the ripple caps you need to have an oscilliscope to test for the ripple
  ----- Original Message ----- 
  From: Donavan 
  To: emax@yahoogroups.com 
  Sent: Friday, July 10, 2009 1:25 AM
  Subject: Re: [emax] Power Supply Voltage Question





  Hi Ted,

  Are you referring to the three pins coming form the AC receptacle: the green to the ground screw, and the blue and brown that go to the Toroid->power switch->AC IN?

  Do you recall where the problem was in the chain I described above? 
  Do you have any insight into the voltage variance? Initially +11.9 seems "close enough", but I know there are some components that draw 0.02 and that missing 0.1 could be enough to cause a cascading problem.

  Also, just testing it now I had head phones plugged into Left Out and as soon as I unplugged the head phones the LCD went out with some residual corruption. I turned the Emax off and back on and the screen was fine. I tried this test two more times and I started to get the whine from the LCD screen (or a component right next to it). 

  Now the forth time I turn it on the screen is off/corrupt from the start, the whine is still there but the disk loads and I still get audio. 

  The fifth time I turn it off and back on the screen is just off completely, the whine is there (gets louder the long the unit is on), the floppy won't load completely and all the LEDs except the one at Record/Preset Management, Dynamic Allocation, Load All and Enter are on, and I get no audio of course.

  My assumption is that the voltage variance is causing this negative effect depending on certain variables, such as heat given that atoms can move around and the atoms can also hold more electrons, disrupting the flow of electrons through the conductor.

  Thanks for the help
  Patrick

  ________________________________
  From: Ted Summers <djtbs1@...>
  To: emax@yahoogroups.com
  Sent: Thursday, July 9, 2009 6:22:08 AM
  Subject: Re: [emax] Power Supply Voltage Question

  My emax rack did this and it turned out to be a bad connection to the 
  power supply on the AC connector.

  Regards,
  Ted

  On Jul 9, 2009, at 12:17 AM, Donavan wrote:

  Hi guys,

  My Emax hasn't been function again lately. I saw a posting by Jimmy 
  Moore with a link to a german site about using an AT PSU. The 
  description of the LCD corrupting and LED blinking is what struck me. 
  My LCD goes blank, sometimes with some corrupt text visible, there is 
  a whine that is comeing from the area of the keyboard by the LCD, and 
  also all the LEDs light up and a CRC message can appear though this 
  happens inconsistently.

  My question is what is the acceptable voltage variance? The 
  diagnostics document I have say the VR1 can have +/- 5% variance, so 
  on the required +5VDC a range of 4.75-5.25 is with in specs.

  Also, someone mentioned that the LCD (emulator_island? ) that the LCD 
  can make this whine, but to your knowledge will this cause the other 
  problems?

  Thanks

  Emax Specs
  Verify +12V on orange wire.

  Verify +SV on yellow wire.

  Verify -l2V on purple wire.

  Verify + 10V on pin 3 of Q2.

  My Test Results20DCV meter setting
  At psu connector at board connector
  orange 11.94V 11.94V
  purp -11.9V -11.9V
  yellow 4.96V 4.94V

  Floppy
  orange 11.94 Yellow 4.94

  200m meter setting
  Floppy
  green - 41 blue/Purp/Wht - 5.1

  Q2 visible circuit path pin
  1 - 10.04
  2-11.93

  3-10.72

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