It's in an old (mid-80's) industrial machine. The French mfr. is out of
business. The circuit I'm trying to resurrect takes a digital measuring
encoder as input and displays the measurement on 7-segment LED displays.
Display went wonky for a few weeks, then went blank, entirely. DC voltages
and ripple are all good. Tried reseating socketed components; no joy.

Lacking any documentation, I'm going to try some "shotgun" troubleshooting by
replacing the major components on the board (they're socketed).

Large components include:
D8085AHC
D8155HC
D8279C-2
uPB8212C
All parts NEC mfr.

When replacing with components available today, what are my limitations? (For
example, I know "H" means HMOS, and that is a "must".) What else should I be
careful re. the letter digits of the p/n's when selecting parts with the same
numerical digits of the p/n's?

I know that the 8279 is a programmable controller, so replacing that without
having the source code to program it with, is out of the question.

Just trying to help a client keep this otherwise good machine in service and
avoid "binning" it.

Thanks,
--
DaveC

This is an invalid return address
Please reply in the news group

On Fri, 24 Feb 2006 11:05:27 -0800, DaveC wrote:

It's in an old (mid-80's) industrial machine. The French mfr. is out of
business. The circuit I'm trying to resurrect takes a digital measuring
encoder as input and displays the measurement on 7-segment LED displays.
Display went wonky for a few weeks, then went blank, entirely. DC voltages
and ripple are all good. Tried reseating socketed components; no joy.

Lacking any documentation, I'm going to try some "shotgun" troubleshooting by
replacing the major components on the board (they're socketed).

Large components include:
D8085AHC
D8155HC
D8279C-2
uPB8212C
All parts NEC mfr.

When replacing with components available today, what are my limitations? (For
example, I know "H" means HMOS, and that is a "must".) What else should I be
careful re. the letter digits of the p/n's when selecting parts with the same
numerical digits of the p/n's?

I know that the 8279 is a programmable controller, so replacing that without
having the source code to program it with, is out of the question.

Just trying to help a client keep this otherwise good machine in service and
avoid "binning" it.

Thanks,

Hi,

All those parts are still available in the market.

Pieter

It sounds as though the instrument is a Digital Readout display
associated with machining or other production equipment.
I don't have much advice for troubleshooting other than what's already
been suggested by Arfa.
It's been too many years, and too little practice since my training in
these types of circuits. I have a completely dead Anilam DRO display,
and I've had difficulty understanding the circuits even though I have a
schematic.

If you proceed with IC replacement, check any datasheets you can find
to confirm that the operating voltages of replacement parts are the
same.

Newer used DRO systems are plentiful, depending upon your searching
abilities. If the linear encoder scales used with the DRO display unit
are the commly used 5 volt TTL squarewave types, you could possibly
just replace the display unit with one that's compatible.

Finding a suitable replacement will probably be a little tougher if the
DRO display also has outputs for interfacing with NC or CNC machine
controls, but numerous displays have various optional modules to
convert inputs to outputs.

There are numerous surplus suppliers of older ICs in the U.S, and more
semiconductor sellers are gradually appearing on eBay.

Cheers
WB
...............

DaveC wrote:
It's in an old (mid-80's) industrial machine. The French mfr. is out of
business. The circuit I'm trying to resurrect takes a digital measuring
encoder as input and displays the measurement on 7-segment LED displays.
Display went wonky for a few weeks, then went blank, entirely. DC voltages
and ripple are all good. Tried reseating socketed components; no joy.

Lacking any documentation, I'm going to try some "shotgun" troubleshooting by
replacing the major components on the board (they're socketed).

Large components include:
D8085AHC
D8155HC
D8279C-2
uPB8212C
All parts NEC mfr.

When replacing with components available today, what are my limitations? (For
example, I know "H" means HMOS, and that is a "must".) What else should I be
careful re. the letter digits of the p/n's when selecting parts with the same
numerical digits of the p/n's?

I know that the 8279 is a programmable controller, so replacing that without
having the source code to program it with, is out of the question.

Just trying to help a client keep this otherwise good machine in service and
avoid "binning" it.

Thanks,
--
DaveC

This is an invalid return address
Please reply in the news group

DaveC wrote:

It's in an old (mid-80's) industrial machine. The French mfr. is out of
business. The circuit I'm trying to resurrect takes a digital measuring
encoder as input and displays the measurement on 7-segment LED displays.
Display went wonky for a few weeks, then went blank, entirely. DC voltages
and ripple are all good. Tried reseating socketed components; no joy.

Lacking any documentation, I'm going to try some "shotgun" troubleshooting by
replacing the major components on the board (they're socketed).

Large components include:
D8085AHC
D8155HC
D8279C-2
uPB8212C
All parts NEC mfr.

When replacing with components available today, what are my limitations? (For
example, I know "H" means HMOS, and that is a "must".) What else should I be
careful re. the letter digits of the p/n's when selecting parts with the same
numerical digits of the p/n's?

I know that the 8279 is a programmable controller, so replacing that without
having the source code to program it with, is out of the question.

Just trying to help a client keep this otherwise good machine in service and
avoid "binning" it.

Thanks,

All of those parts were originally from INTEL. NEC was a second
source. What type of RAM does it use?

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

"Michael A. Terrell" a écrit dans le message news:
...
All of those parts were originally from INTEL. NEC was a second
source. What type of RAM does it use?

8155 contains a "small" RAM 256 bytes
Suffisant for the stack and some data.

Another saved RAM is probably located on another board

--
Guy Pastuzak

Adresse ANTISPAM
ANTISPAM address

guy pastuzak wrote:

"Michael A. Terrell" a écrit dans le message
news: ...
All of those parts were originally from INTEL. NEC was a second
source. What type of RAM does it use?

8155 contains a "small" RAM 256 bytes
Suffisant for the stack and some data.

Another saved RAM is probably located on another board

--
Guy Pastuzak

Adresse ANTISPAM
ANTISPAM address

Actually it is a whole 2 kB.
--
JosephKK
Gegen dummheit kampfen die Gotter Selbst, vergebens.
--Schiller

guy pastuzak wrote:

"Michael A. Terrell" a écrit dans le message news:
...
All of those parts were originally from INTEL. NEC was a second
source. What type of RAM does it use?

8155 contains a "small" RAM 256 bytes
Suffisant for the stack and some data.

Another saved RAM is probably located on another board


I've never used the 8155 and don't think I have a datasheet in my
collection, so I wasn't familar with it.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

http://www2.okisemi.com/site/product...bsolete_MPUDoc

The datasheet of 8155 is available at the above as MSM81C55-5RS

Allen

http://www2.okisemi.com/site/product...bsolete_MPUDoc

The datasheet of 8155 is available at the above as MSM81C55-5RS

Allen

On Sat, 25 Feb 2006 17:32:16 GMT, "Michael A. Terrell"
put finger to keyboard and composed:

DaveC wrote:

It's in an old (mid-80's) industrial machine. The French mfr. is out of
business. The circuit I'm trying to resurrect takes a digital measuring
encoder as input and displays the measurement on 7-segment LED displays.
Display went wonky for a few weeks, then went blank, entirely. DC voltages
and ripple are all good. Tried reseating socketed components; no joy.

Lacking any documentation, I'm going to try some "shotgun" troubleshooting by
replacing the major components on the board (they're socketed).

Large components include:
D8085AHC
D8155HC
D8279C-2
uPB8212C
All parts NEC mfr.

When replacing with components available today, what are my limitations? (For
example, I know "H" means HMOS, and that is a "must".) What else should I be
careful re. the letter digits of the p/n's when selecting parts with the same
numerical digits of the p/n's?

I know that the 8279 is a programmable controller, so replacing that without
having the source code to program it with, is out of the question.

Just trying to help a client keep this otherwise good machine in service and
avoid "binning" it.

Thanks,

All of those parts were originally from INTEL. NEC was a second
source. What type of RAM does it use?

The 8155 has on-chip RAM.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Every one of those is available as Intel, TI, or NEC, and maybe
others. They were very common components and turn up all the time.
You can get tubes of them on Ebay cheap, and a google search should
turn up sources for all of them.




DaveC wrote:
It's in an old (mid-80's) industrial machine. The French mfr. is out of
business. The circuit I'm trying to resurrect takes a digital measuring
encoder as input and displays the measurement on 7-segment LED displays.
Display went wonky for a few weeks, then went blank, entirely. DC voltages
and ripple are all good. Tried reseating socketed components; no joy.

Lacking any documentation, I'm going to try some "shotgun" troubleshooting by
replacing the major components on the board (they're socketed).

Large components include:
D8085AHC
D8155HC
D8279C-2
uPB8212C
All parts NEC mfr.