• Please review our updated Terms and Rules here

Who knows something about the old NEC PC-6001A around here?

My PC-6001 had a bad diode in the AC DC rectifier that once replace fixed things up. If you can disconnect the rails from the main board, you can measure resistance on those rails to see if any are shorted. Though they may not show as shorted until power is applied, and small clamp meter on them could show you the current to see if it is over spec. Also, if there are any bad tantalum caps, if you have a thermal camera, they will show up as heat if they are shorted.
 
Thanks, the NEC C2373 looks like a package with two diodes back to back. Normally one of the output voltages is fed back to a control circuit on the primary side.
Regards,
John
 
alank2 said:
My PC-6001 had a bad diode in the AC DC rectifier that once replace fixed things up. If you can disconnect the rails from the main board, you can measure resistance on those rails to see if any are shorted. Though they may not show as shorted until power is applied, and small clamp meter on them could show you the current to see if it is over spec. Also, if there are any bad tantalum caps, if you have a thermal camera, they will show up as heat if they are shorted.
Click to expand...
Alank2 do you live in the US? Do you feed your 6001 120ac or do you use a step down converter to 100?
 
I've always just fed it 120 VAC, and my house tends to run 125 VAC-ish and it has not been a problem so far. (Though who knows, maybe that is what took out that diode the first time I got it. The VERY first time I turned it on after getting it from eBay it lasted about 3 seconds).
 
1980s_john said:
Thanks, the NEC C2373 looks like a package with two diodes back to back. Normally one of the output voltages is fed back to a control circuit on the primary side.
Regards,
John
Click to expand...
You were right John I ended up measuring 5v while attached to the board and it brought it down from 5.4 to a steady 5. It was on the lower side when I initially tested it on the board since I had adjusted that variable resistor so I reverted that back to 5.4.

12v is still shorted to ground on the logic board so could not measure but measured not connected to the board it was 10v. I think you are right it probably needs a load on the 12volt side as well. I am just going to focus on the 12v short on the logic board now and leave power supply alone.
 
Caps came in. I replaced C3 and C4 which were shorting the 12 and -12 rails on the board. I hooked her back up and bingo she lives again!

IMG_4047.jpeg

Voltages all look good so going to leave power supply alone for now. Keyboard also working. Speaker seems to be working as well, obnoxiously making chirps with each key press. Ill try to get some software on it to test it out further. Thanks for all the help getting it back up and running :)
 
You can switch to an orange screen coloring as well using the screen command!
 
I have a similar problem as mbliss11. Recently picked up another PC-6001. I get a blank screen, unresponsive unit. I'm using 120v US wall current.
-12 comes up as 13.5
+12 comes up as 16
+5 comes up as 5.4
without load, which may correct with load, from what I'm reading.

I found the 4 blue tantalum capacitors on the main board C4 and C5 demonstration continuity between the legs- does that mean they are shorted? C2 and C3 do not.

If that is the problem, what are the suggested replacement parts? Are there any other caps or parts I should replace prophylactically while I have this computer disassembled?

And it was fun reading the earlier posts in this thread. Way back in 2017, I was the guy who was sent the cart dumper to dump my collection of carts.
 
Yes, if there's close to zero resistance between the legs of the tantalums closest to the power entry connector, they're shorted and pulling down the output from the power supply.

I replaced mine with cheap 22µF aluminum electrolytics, but keep in mind that the polarity markings are different on tantalums (positive has the stripe on those.)
 
You can also use a thermal camera if you have one to spot shorted tantalum caps.
 
So I am revisiting the 6001. I have a Maxduino cassette loader and I believe a cable that should work with the machine (5 pin din for cpc and msx standard). Trying to load some games using cload command but am not getting anywhere.

From my research programs expect a certain page size and mode when launching. My machine is stock so maximum amount of pages I can do it 1 or 2. Screen mode I am lost on. Is that just the screen command?

Any suggestions on a game that will load on a stock 16k 6001 via cassette?
 
Let me look around and see what I can find. I know it is released in digital .p6 format, but trying to load it from that isn't always so easy. It has a loader which then loads the binary part from cassette. I think I converted it to from from diskette which you could probably get working in an emulator, but on the real thing you probably need the cassette. You can search nec trek demo on YT to see what is on the demo cassette. I have one, but my tape deck I used to make copies has died from drive belt failure. Let me see if I have it in digital form - I might have a .WAV copy of it I can post to archive.org for you.
 
alank2 said:
Let me look around and see what I can find. I know it is released in digital .p6 format, but trying to load it from that isn't always so easy. It has a loader which then loads the binary part from cassette. I think I converted it to from from diskette which you could probably get working in an emulator, but on the real thing you probably need the cassette. You can search nec trek demo on YT to see what is on the demo cassette. I have one, but my tape deck I used to make copies has died from drive belt failure. Let me see if I have it in digital form - I might have a .WAV copy of it I can post to archive.org for you.
Click to expand...
That would be awesome thank you!!
 
Look for : "NEC Trek Demo (Magicsoft Corp USA - NEC)"

There is a p6towav program I found on a Japanese website that I *think* can convert p6 to wav files.
 

Attachments

  • p6towav.zip
    10.4 KB · Views: 3
You must log in or register to reply here.
Back
Top