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minimum suitable voltage for a 5140?

E

erikarn

Experienced Member
Joined
Dec 14, 2020
Messages
65
Location
Oakland, California
hi!

I've acquired a 5140 in bad shape and missing the battery/power supply.

I've cleaned it up as best i can and I'd like to power it with what I have here. Yes, I've ordered a NOS (hopefully!) 15v 5140 power supply that'll be here in a couple weeks.

So!

* can I run it without the batteries installed?
* what's the minimum voltage I can supply it and have the thing come up?

I tried a regulated 12v 5A supply but it will just beep once with the boot-up beep, then go dead. I'm guessing power-good isn't very good :)

thanks!
 
It will run without the batteries installed, but it'll be annoying because it'll lose its setup information and make a fuss out of it if you unplug it.

If you happen to have the original battery pack and are planning to re-cell it please take a lot of pictures of what's inside and what the polarity of the contacts are. I don't have a pack at all; it's been on my list to try making a simple taped-up substitute after I can find suitable thermal fuses to keep it from going nuclear if something goes wrong with charging, but I don't think the service manual has the polarity of the connector documented.
 
modem7 said:
That information is in the 5140's technical reference.
See also, post #4 of the thread at [here].
Click to expand...

Hi,

Well, mine doesn't really do very much at a regulated 12v or 13.8v.

Does anyone have schematics? I can see 12/5v power on the power edge connector, but I'm at a loss right now figuring up if the right bits of the board are receiving power and how the power sequencing works.


-a
 
ok, i lie - it's a busted power switch. delicately poking it so it does its momentary thing works.

now, the display is busted. time to figure that out.

thanks!


-
 
Eudimorphodon said:
It will run without the batteries installed, but it'll be annoying because it'll lose its setup information and make a fuss out of it if you unplug it.

If you happen to have the original battery pack and are planning to re-cell it please take a lot of pictures of what's inside and what the polarity of the contacts are. I don't have a pack at all; it's been on my list to try making a simple taped-up substitute after I can find suitable thermal fuses to keep it from going nuclear if something goes wrong with charging, but I don't think the service manual has the polarity of the connector documented.
Click to expand...

I don't have the battery pack but i can just go measure the battery pack voltage for you when charging. That'll tell you what it needs to be for wiring.

I mean, I have some 90C thermal fuses for other reasons but they're likely too high for the NiCDs. My bet is it needs to be something lower like 50C.
 
And my 5140 works fine save a dead screen, and replacement 640x200 LCDs from that era are like $300 a pop minimum. So, I may have to go learn Verilog and make a bloody scan converter to VGA. The timing is a bit oddball, 50Hz refresh rate @ 640x200. I'm hoping that doubling it to 640x400 and adding the needed padding for VGA will fall within spec of le olde LCD monitors so i don't need to do it a /frame/ at a time...
 
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