View Full Version : NEC APC No Video and More

August 22nd, 2010, 08:21 PM
I just got back from a trip up to meet Glitch and get some machines from him, among which was the NEC APC he was holding for me from that thing where somebody was giving out a whole bunch for free with docs.

Anyway I hooked mine up and tried turning it on, and nothing. The power light in the on/off switch lit up, so it got power. I heard no noise, and saw no image - not even a black glow, the screen didn't appear to power on.

Now, my first assumption was that something should happen with no disk. I have no 8" disks with which to test this machine, and I know little about it. The Operator's Manual said nothing about how to open it, and I couldn't figure out how to remove the top cover, so I can't check inside.


August 23rd, 2010, 04:31 PM
Figured out how to open it - there are two clippy things made of metal on the bottom on either side. You have to make sure that nothing is screwed through them to hold them in place, and then move them, pushing up on the cover as you do so.

Anyway, after opening it I was able to guess better. The fan inside doesn't spin, and when one combines that with the fact that no image displays, I'd wager that it's either a PSU problem or a problem with the battery. The battery is in OK shape, it's a lithium 3v cell, a tall battery.

Does anybody know anything about these units?

Found this thread:

Mine's completely different inside.. I have two cards in mine, and after pulling them out and cross-examining them with his list (and looking at the chips) I've determined that I have a graphics card/fdc and an 8086 cpu card. I don't have a second graphics controller, but that isn't necessary for operation.

Again, nothing except the power switch has power, it seems.. I think the PSU is under the CRT, so it's not easy to examine. All the caps I am able to see (mostly around the CRT) look to be in good shape, no bulging...

Still at teh same conclusion, either the PSU or the Lithium Battery. I am going to see if I have a coin cell that's 3v to test with..

Edit 2:

Found two fuses (one thinner one thicker wire inside) near a moderately large capacitor on a board next to the CRT. I pulled them out and checked them, both look OK as far as I can tell.

Edit 3: Got my multimeter working (wouldn't turn on last night for whatever reason) and tested the battery. As far as I can tell (can't read this electric multimeter for crap) it has power, so I'll assume it's the right amount.

This leaves the PSU, but I have no idea what else to check besides those fuses I already checked - I'm not even certain how to open the machine further to look at the PSU. I really could use some help.

Just realized - maybe this should have been in the CP/M section..? It's got an 8086 and can run CP/M, so tough call. :P

August 24th, 2010, 10:13 AM
Can a moderator move this to the CP/M section? I don't think I'm getting the right people to look at this.

August 26th, 2010, 07:58 AM
Nobody knows anything about this or has any idea based on my descriptions? If I need to give you more info, pictures, anything, please ask.. :/

August 26th, 2010, 09:27 AM
It's a tough one, I'm not seeing much documentation for it out there other than a few comments from collectors. When you've had it apart you don't see any glow at all from the back of the tube? You're right as far as the first step is verifying your power supply is putting out the needed/required voltage. Is there an obvious connection from the power supply that you can unplug and test the voltages? Keep searching for some documentation/manuals/schematics. You may even try contacting anyone else around here or the web that you find has one to see if they have any tips on troubleshooting or if they've scanned the docs.

August 26th, 2010, 09:47 AM
If anyone spent any time searching this forum, they'd know that it's been stated more than once that the NEC APC was known as that only in Western (mostly US) markets. Otherwise, it was known as the N5200. I find it remarkable that NEC maintained support and documentation (http://www.nec.co.jp/contactus/business.html#n5200) on this model right up through 2009. Of course, that's gone now, but I suspect there are a fair number of copies floating around in the Japanese PC98 community--all one need do is run down a forum and ask.

Don't leave it to gray-haired technologically-backward geezers like me to do it for you. Information on anything is easy to come by in comparison to the days when you'd spend hours on the telephone and FAX trying to get a glimmer of light.

And keep off my lawn. :cursemad:

August 26th, 2010, 01:25 PM
The problem is that sometimes you have to know what to look for - I had read somewhere that the internal name was the N5200 but didn't think to search for docs under that name. Thanks.

I'll report back with whatever I find to further our forum's collective knowledge.


I'm unable to find a damn thing. :(

I can't even locate a PC98 forum, English, Japanese or otherwise. The only thing I did find was the NEC n5200 FAQ which seems to have ended up being composed of information for several machines and the only information pertaining to the n5200 itself was pretty useless (at least to me).

As for searching for the information directly, the n5200 is the model name of many things, but even after a selective search omitting several phrases I turned up very little in the way of technical information. Mostly I found Japanese sites containing broad overviews of the PC98 series and a brief mention or short page on the n5200/APC.

August 26th, 2010, 02:42 PM
Blind advise (usually I do the search myself first) but have you tried things like google groups, google books, other publication archives? Maybe (odd and malware prone) a torrent site search which may have docs or search the forums here? You said you got this from Glitch, Glitch, have you tried yours or have some docs hiding anywhere?

August 26th, 2010, 03:12 PM
Crikey, in about 10 minutes I found a N5200 emulator, as well as lots of threads taking about this system.


Try dropping an email to Toshiya Takeda and see if he can point you in the right direction.

August 27th, 2010, 09:18 AM
I did find an emulator, but that didn't really help, heh. I must admit, the thought never crossed my mind to ask the guy who wrote it - I've done so now.

I suppose I've been spoiled by the abundance of information on the machines I've worked with so far.. :/

Newsgroups reveal a lot of N5200/APCs for sale in the late 80s and early 90s, but little else that I hadn't already found through a web search.

August 27th, 2010, 11:54 AM
My point is that the APC was never really popular outside of a few institutions in North America. Because it's part of the PC98 family (the business section), it hung on for a long time in Japan. So Japan is where you want to go for information.

Asking here is like asking for advice on getting a Multi-16 going.

August 29th, 2010, 08:47 AM
This leaves the PSU, but I have no idea what else to check besides those fuses I already checked - I'm not even certain how to open the machine further to look at the PSU. I really could use some help.

The PSU on my NEC APC is accessed by removing two screws under the monitor.



October 4th, 2010, 05:57 PM
Thanks for that info - dunno how I missed that panel.

Inside the PSU is an open circuit, no metal box like today. On the bottom of the circuit I saw some brownish residue I assume is normal around each solder point. One area was black, but it doesn't appear to be from a dead component. I found a fuse and it's black and silver on the glass part, so I assume it's blown.

It's rated 125V/5A for anybody who might search this up later. I am going to try to find a replacement tomorrow and let you know how it goes.

Wish I'd seen your post sooner, SteveH, heh.

October 4th, 2010, 06:46 PM
Post pictures of the power supply board -- if a fuse that hefty blew, there's probably a reason for it.

October 5th, 2010, 07:26 AM
Upon closer (daytime) examination of the board, I noticed slight corruption on the bottom of a pin sticking through the blackened area of the board. I took pictures of the whole board on both sides, closeups of 1/4 of the board at a time top and bottom, and then special closeups of the suspect area and the big middle... thing.. (wonky coil?)

http://img215.imageshack.us/img215/7161/p1010191i.th.jpg (http://img215.imageshack.us/i/p1010191i.jpg/)http://img535.imageshack.us/img535/2697/p1010192f.th.jpg (http://img535.imageshack.us/i/p1010192f.jpg/)http://img80.imageshack.us/img80/8187/p1010193l.th.jpg (http://img80.imageshack.us/i/p1010193l.jpg/)
http://img837.imageshack.us/img837/3408/p1010194iq.th.jpg (http://img837.imageshack.us/i/p1010194iq.jpg/)http://img214.imageshack.us/img214/1469/p1010195q.th.jpg (http://img214.imageshack.us/i/p1010195q.jpg/)http://img59.imageshack.us/img59/2411/p1010196i.th.jpg (http://img59.imageshack.us/i/p1010196i.jpg/)
http://img696.imageshack.us/img696/7685/p1010197w.th.jpg (http://img696.imageshack.us/i/p1010197w.jpg/)http://img713.imageshack.us/img713/6980/p1010198o.th.jpg (http://img713.imageshack.us/i/p1010198o.jpg/)http://img687.imageshack.us/img687/556/p1010199xq.th.jpg (http://img687.imageshack.us/i/p1010199xq.jpg/)http://img835.imageshack.us/img835/1805/p1010200o.th.jpg (http://img835.imageshack.us/i/p1010200o.jpg/)http://img839.imageshack.us/img839/301/p1010201p.th.jpg (http://img839.imageshack.us/i/p1010201p.jpg/)http://img201.imageshack.us/img201/1285/p1010203f.th.jpg (http://img201.imageshack.us/i/p1010203f.jpg/)http://img178.imageshack.us/img178/6434/p1010204.th.jpg (http://img178.imageshack.us/i/p1010204.jpg/)

Again, nothing on the topside looks blown (to my electronics amateur eyes) - it's possible that the blackened part of the board is from an old part that blew and was already replaced..

October 5th, 2010, 07:55 AM
If you could get a better picture of diode D7, that'd be good. It looks like it might be blown, or just fractured. It's near the large device in the center (which is a high-frequency transformer...so yes, a coil of types)

October 5th, 2010, 08:08 AM
Oy - don't need another picture - it's cracked down the middle! :O

I dunno how I didn't see that, hah - was too busy looking at the big teal bugger next to it I suppose.

So.. need to replace that, eh? Mine's rather unreadable, any shot of you opening your unit and letting me know what that part is?

Once I have a part number I'll see if my friend (who has a far more modern soldering iron and actual soldering training) will replace it for me.. That and I'll replace the fuse.

Wait.. you said "just fractured" as though that wasn't a bad thing? I assume it's not fixable without a new component still, it's just better for the board if something doesn't explode?

October 5th, 2010, 08:13 AM
One step ahead of you -- already pulled the board and looking at it to figure out the part #!

"Just fractured" means it died non-catastrophically. Since yours did in fact burn out, there's a possibility it took something else with it. Really it's probably just an overloaded diode though, being next to that big power resistor probably overheated it.

EDIT: I pulled the diode D7 out of my power supply...the only marking on it is "14" which isn't very helpful. You can /probably/ replace it with a UF4004, unless it's used in an application where more than 1 A will be flowing through it. One of its traces leads up to a bunch of high-wattage resistors and a film capacitor, so I'd guess it's some sort of suppressor circuit and won't have much continuous draw.

October 5th, 2010, 08:19 AM
Well it has a huge crack down the middle, but it doesn't look "exploded" - i.e., all the pieces are there, it's just not easily readable with the big split and blackened tone covering the text. If it weren't for the blackness on the bottom of the board I'd call it fractured rather than burnt.

Agent Orange
October 5th, 2010, 02:31 PM

When you yank that diode (assuming you can get it out in one piece), take a multimeter and check for 10 to 1 front to back ratio (ohms). On second thought, before you take it completely out of the circuit, lift one end and then check it. If you see 10 to 1 chances are something else went 'bump in the night". So, I wouldn't just stop there - poke around a little.

October 5th, 2010, 03:14 PM
After removing the diode (or one end of the diode) you should also make some resistance readings
between the diodes endpoints and the circuit ground to see if there is a short somewhere. If glitch
has a working system and could measure those same points in his power supply it would help.

October 5th, 2010, 08:28 PM
I shall do these things when I get a chance to get my friend over to assist - not sure when that will be, however.

October 7th, 2010, 04:37 AM
Thanks for this informative post.


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