Emax

My problem was the AC connector (blue and brown) right on the power  
supply. The connector was white (but discolored brown as it was burnt  
up). When looking at the pins they were heavily oxidized or burnt so  
looked the metal was "flat" or matte, not shiny / gloss at all-  
somewhat "blackened" I can't really describe it better than that.

If you fix equipment, you know what burned pins look like. If you  
don't fix equipment it can be hard to describe....

Thx,
Ted

On Jul 9, 2009, at 6:02 PM, jammie wrote:



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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