Emax

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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