My Emax behaved quite oddly. The machine would boot properly. Nonetheless the floppy drive wouldn't work and I got the distortion of death aka "Sorry mate, your E-Chip is dead". The E-RAM test in the diagnostics menu failed and displayed the exact error code that can be found in the E-mu Diagnostics pdf (Link see below). However, I noticed the Emax worked (though instable) when the voltage was exactly set to 5.13V ... seemed like the PSU was up something...
So I replaced the PSU with an
ASTEC LPT42-M (PS.: This one should also do the job: MW RT-65B). The Emax draws roughly 15-20 watt - depending on your configuration - so no need to go overboard.
What can I say - everything works perfectly fine again. I even feel like it reduced the noise on the audio jacks to an absolutely inaudible level, speeding up menu response times as well as the bank loading times.https://www.flickr.com/photos/75453658@N08/46848507344/in/dateposted-public/It takes a little effort, but it's well worth it. (Also works for the Emax II)
1) Buy one: Depending on where you live, they should be less than ~40 (euros/dollar/pounds) with all the major electronics shops. There's a guy on eBay Germany selling them for 20euros:
https://www.ebay.de/itm/2233530895202) Also search for something along the lines of "3.96 Connector Housing" and get the corresponding "crimps" as well. Usually the housing and the crimps are sold as a bundle. They are available on every continent so make sure you don't get ripped off and pay more than 5 quid (incl. shipping).
3) Cut and drill a little wooden (etc) mounting plate as the new PSU is slightly smaller than the old one.
4) Familiarise yourself with the datasheet of the PSU:
https://www.jameco.com/Jameco/Products/ProdDS/173104.pdf5) Familiarise yourself with the colour code of the Emax power cords; page 7:
https://nonaudio.files.wordpress.com/2013/06/emax-diagnostics.pdf6) Remove the old PSU (and dump it. There's really no point in trying to fix or recap anything). Modern day PSU's are of better quailty anyway.
7) Crimp, solder and isolate (heat-shrink tubing) the wires as can be seen in the picture above.
Only one lead per colour code needs to be connected to the PSU (But it's fine if you use the other 5V and Ground pin). Solder the other ones to the cable which goes into the PSU (and isolate the junction).
8 ) OPTIONALLY: From the PSU documentation: "Mounting holes M1 and M2 should be grounded for EMI purposes". M1 already is, so solder a short wire from M2 to GRD. Not sure about the exact physical effect behind it, but you may as well do it while you're at it.)
9) Connect the PCB power connector, the (green) ground wire as well as the "ON/OFF" switch to the new PSU. Ignore the two cables of the 110/220V switch and isolate them using heat shrinking tubes. The new PSU automatically recognises whether it is connected to 110V or 220V.
THINK AGAIN: ARE THE COLOUR CODES CORRECTLY ALIGNED TO THE PINS OF THE NEW PSU? IS EVERYTHING PROPERLY ISOLATED?
10) BEFORE switching on the Emax. Turn the little poti on the PSU all the way to the
left (just in case its default position has been all the way to the right.)
11) Connect a multimeter to the PSU (5V and Ground) and turn on the machine. You should be measuring 4.8V. Also the HD and floppy drive might not spin yet.
12) Carefully turn the little potentiometer to the right until it reaches 5,05V.
13) Turn off the machine again, and switch it on again.
It should boot /operate normally now and your issues should have disappeared. If your still facing issues, at least you know for sure the problem lies elsewhere and you got a new PSU for the future. If it smells burnt/something has "snapped", immediately switch off the device, get a beer and cry into a pillow.
DISCLAIMER: Even though this is a simple and straightforward fix for anybody who knows how to operate a solder iron or who knows how to ask somebody who knows how to operate a solder iron, I do not assume responsibility for any errors or damage caused by replacing the PSU. NEVER FORGET: The exposed metal on the supply conducts high and potentially LETHAL voltage! Do not touch the supply while it is operating AND connected to the power plug.
Author