Circa 1985 ish, I used to buy 8201A's by the five unit case.
Still have ~ two dozen of the 8201A's ...and STILL use them for data collectors 
via soft-ware / programs I wrote and simple CMOS interface .
I wrote programs, in basic, to transfer data back and forth between the PC and 
the NEC.
Still use that VERY old ~64k BASICA.exe in a Windows shell on a linux operating 
system...
More recently I will monitor ebay any pick-up a 8201A ...if the price is 
'right'.

I have 'all' the circuit manuals, but generally just test, for example, a good 
screen - keyboard - etc. for the bad one to attempt to isolate the bad 
component or problem.

These are rugged units.  I don't remember one failing in the field where they 
were housed in a simple aluminum box in freezing cold or summer heat.
 ...arguably after working with both the RS cousin and the Kyocera (spelling?) 
I found the 8201A more fitting for my needs.   I still have both of the cousins.

I have two or three never used NEC 8300, which followed the 8201A, (...but 
TOTALLY redesigned ) in their pristine original 'handled' boxes and the 
original five unit shipping case. All with matching serial numbers.
Likely, a couple of very few virgin machines in the world.

Hope you can make your 8201A's operational.  They were AND still are good 
little machines...

Regards,

Richard Oaks
=====================
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Sent: Saturday, May 25, 2019 16:40
To: [email protected]
Subject: M100 Digest, Vol 101, Issue 13

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Today's Topics:

   1. Dead NEC Units (Kurt McCullum)
   2. smoke on the water.... (Ed Graffius)
   3. Re: Dead NEC Units (Stephen Adolph)
   4. Re: Dead NEC Units (Josh Malone)


----------------------------------------------------------------------

Message: 1
Date: Fri, 24 May 2019 17:22:56 -0700
From: "Kurt McCullum" <[email protected]>
To: [email protected]
Subject: [M100] Dead NEC Units
Message-ID: <[email protected]>
Content-Type: text/plain; charset="us-ascii"

I've got two NEC 8201s that are both dead. I'd like to get them up and running 
again. Especially the one with the Japanese keyboard. Has anyone put together a 
list of what to check to diagnose where the problem might be. I have done the 
power supply test from the service manual and the CPU seems to be correct but 
I'm not sure where to start. Both units turn on with a blank screen.

Kurt
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Message: 2
Date: Sat, 25 May 2019 04:32:43 +0000 (UTC)
From: Ed Graffius <[email protected]>
To: [email protected]
Subject: [M100] smoke on the water....
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"

no I didnt blow it up in the bathroom tub.? I programmed it to play smoke on 
the water.?? didja know the docs about the sound function are wrong?? the tone 
gets higher as the number gets LOWER, not the other way as the docs state
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Message: 3
Date: Sat, 25 May 2019 08:22:39 -0400
From: Stephen Adolph <[email protected]>
To: [email protected]
Subject: Re: [M100] Dead NEC Units
Message-ID:
        <CAMCMnV6RHe2Lw_DXC-d-_e=jRjY9Gp=obg3fxivyp3waxew...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Kurt, do you have a scope?
I would certainly try reseating any socketed parts.  Main rom is socketed
for sure.
Then I would start at the clock and work forwards.
* verify the CPU has clock
* verify the CPU control lines are toggling
* look at the address and data lines for toggling and level

if that all looks ok then, pin by pin on the main rom, check for toggle and
level.
again for the ram modules.
to make it easy remove as many ram modules as you can.

check DC on the power supplies of course.

On Fri, May 24, 2019 at 8:41 PM Kurt McCullum <[email protected]> wrote:

> I've got two NEC 8201s that are both dead. I'd like to get them up and
> running again. Especially the one with the Japanese keyboard. Has anyone
> put together a list of what to check to diagnose where the problem might
> be. I have done the power supply test from the service manual and the CPU
> seems to be correct but I'm not sure where to start. Both units turn on
> with a blank screen.
>
> Kurt
>
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Message: 4
Date: Sat, 25 May 2019 09:37:18 -0400
From: Josh Malone <[email protected]>
To: [email protected]
Subject: Re: [M100] Dead NEC Units
Message-ID:
        <CAB==womgofo0mw01-nbykjptjyjgjbygvzfusqlxbjtdsch...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Does the no-screen BASIC test work? (Cold-start, enter, B E E P, enter)

On Sat, May 25, 2019, 8:22 AM Stephen Adolph <[email protected]> wrote:

> Kurt, do you have a scope?
> I would certainly try reseating any socketed parts.  Main rom is socketed
> for sure.
> Then I would start at the clock and work forwards.
> * verify the CPU has clock
> * verify the CPU control lines are toggling
> * look at the address and data lines for toggling and level
>
> if that all looks ok then, pin by pin on the main rom, check for toggle
> and level.
> again for the ram modules.
> to make it easy remove as many ram modules as you can.
>
> check DC on the power supplies of course.
>
> On Fri, May 24, 2019 at 8:41 PM Kurt McCullum <[email protected]> wrote:
>
>> I've got two NEC 8201s that are both dead. I'd like to get them up and
>> running again. Especially the one with the Japanese keyboard. Has anyone
>> put together a list of what to check to diagnose where the problem might
>> be. I have done the power supply test from the service manual and the CPU
>> seems to be correct but I'm not sure where to start. Both units turn on
>> with a blank screen.
>>
>> Kurt
>>
>
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