Unknown board for car need fix.

[sean0118]

Zooming in reveals the part missing.

Where did you even find that pic? Or do you have the board in your possession?

It's good to have another image of the board but Jonazz did post an image of the missing part earlier, it's a National Semiconductor "8432 1573 REL".

I'm guessing 8432 will be the datecode and REL might mean high reliability? But 1573 doesn't seem to exist online. We need someone with some old National Semi databooks... 

I read on one of the car forums that the board is supplied with 12V. Both the HD44790 (which apparently drives the odometer display and records miles) and the 52801 EEPROM require 5V. So it seems this may be a 5V regulator? Unless 5V comes from off board as well?

[GeorgeOfTheJungle]

and the 52801 EEPROM

Where's that?

[sean0118]

and the 52801 EEPROM

Where's that?

It's the DIP package, you can just make it out with the photo Haenk posted. It's mentioned on the car forum i linked too. Maybe Jonazz could confirm it does say "52801"?

[SilverSolder]

I do think it is impossible to find a skrapped board to install it into my car..
Not many cars had these digital dashes...
Also for the time they.. where unstable but cool looking!
And this is only the first board the preowers all ready took it out... after this board i have to go into all the other boards.
Did not know that only that small part was that rare.. :/

If you are a big manufacturer (like AC Delco, who probably made this board), it is common to buy "special versions" of electronic components.  These specials will get unique part numbers for that particular manufacturer.  There may be no difference at all between the standard part that it is based on, other than giving AC/Delco a special quantity discount without depressing the pricing for the standard part!

So the trick here is to identify which standard part that AC Delco's "saturday night special" actually is under the hood.

Most of the "unstable" problems are likely to be the connectors, rather than the electronics themselves!  -  perhaps time to get acquainted with products like DeOxit and VW's "Stabilant 22" to keep this 'bird flying...

[Jonazz]

Eprom does say 52801 yes.

[YetAnotherTechie]

What is the part number for the little transistor next to the eeprom?

[PaulAm]

Should be pretty straightforward to follow the traces and confirm that it's a 3 terminal regulator (look up the data sheets on the other chips and see if the Vcc lines go to the chip.  That will also give you the voltage).  Back in 88 they're not going to be doing anything particularly tricky in a 3 terminal device.  Hopefully they used the standard pinout.

[jancumps]

Should be pretty straightforward to follow the traces and confirm that it's a 3 terminal regulator (look up the data sheets on the other chips and see if the Vcc lines go to the chip.  That will also give you the voltage).  Back in 88 they're not going to be doing anything particularly tricky in a 3 terminal device.  Hopefully they used the standard pinout.

I first thought it was a 3-terminal device too, but it's a TO-220-5. 5 pins.

[PaulAm]

Maybe something like an LT1529, but what was contemporaneous in 1988?

Same deal though, trace the connections and see if it looks like it should be a 5 terminal regulator.  Seems like the most likely thing, that package is for handling significant power.

[james_s]

I have seen linear regulators that have an enable pin in a 5 pin package like that. Either way tracing out that part of the circuit and drawing a schematic ought to make it obvious.

[fzabkar]

If it's a switcher, then where is the inductor?

Here is the EEPROM datasheet (5V only):
https://www.thirdgen.org/forums/attachments/electronics/302778d1463432237-hacking-into-86-88-ncr52801-datasheet.pdf

I have checked my 1982 NS Linear Data Book, but there are no "1573" parts.

Maybe it's worth trying here:

www.bitsavers.org/components/national/_dataBooks/

Nothing here either:

http://www.bitsavers.org/components/national/_dataBooks/1984_National_Linear_Supplement.pdf

It seems odd that the designer used vibration resistant capacitors (as per MIL spec), but did not anchor the regulator in a similar fashion.

Some alternative pinouts:

https://www.ti.com/lit/ds/symlink/lm2931-n.pdf
www.ti.com/lit/ds/snvs770i/snvs770i.pdf

[james_s]

I thought perhaps those cylindrical black components could be inductors but I'm not sure, if I had the board in front of me I could figure all this out in about 5 minutes but I don't so I have to rely on the pictures. If I can find the time I'll print out the pictures of both sides and reverse engineer the regulator section but I'm fairly busy with my day job and other chores so I can't make promises.

The part is almost certainly house marked, this is or at least was a very common practice. The numbers printed on it will have significance only to the manufacture, it is their own part number printed on what is almost certainly a standard part.

[fzabkar]

Here is a fixed, dual output, 5V + 5V, linear regulator that was available in 1984 (LM2935TV):

https://www.onsemi.com/pub/Collateral/LM2935-D.PDF

It was designed for automotive applications.

[Haenk]

(nonsense deleted)

[fzabkar]

@Jonazz, you have been asked twice to trace the Vout and ground pins of your mystery part. Please help us to help you.

You have the datasheets for the MCU and EEPROM, so you know their Vcc and ground pins. Now use the continuity mode of your multimeter to locate the corresponding regulator pins.

Also measure the voltages coming into the PCB. One of them will be the +12V battery supply.

[fzabkar]

From that other forum …

https://www.thirdgen.org/forums/electronics/732858-hacking-into-86-88-a.html

H: to F from speedometer, +12 V, hot in run
G: pin 15 (from big digidash conn), to H from speedometer, VSS input LT GRN/BLK wire
F: pin 16, +12 V, hot in run
E: pin 19, display dim input, did not use this one
D: not used
C: pin 21, +12 V, hot at all times
B: not used
A: pin 24, GND, to fuse G118

[stevelup]

you just kicking me and pissing on me.
Hope you feel good there back behind your screen.

I think you are -massively- overreacting. No one has been that rude really. The point about links -vs- embedded images was a fair one, as was the fact that you gave no information about the vehicle.

If anyone has been rude, I’m afraid it was you.

[fzabkar]

After reading the detailed explanation at thirdgen.org, it appears that the EEPROM stores the odometer reading in 10 mile increments. This is because it has a finite number of write cycles, namely 10,000. Its capacity allows for 8 odometer readings consisting of 32-bit words (including ECC bits). So 10,000 x 8 x 10 miles = 800,000 miles.

The in-between odometer readings are preserved in the MCU when the ignition is switched off. This would support the idea of separate 5V standby and 5V run supplies.

Edit:

Here is the OP's original thread:
https://www.element14.com/community/thread/74328/l/pontiac-firebird-88-board

Pontiac 1988 Firebird Service Manual
https://depositfiles.com/files/ty1vrpu5x (102MB)

Page 1425 shows connector C2.

pin 21 = battery voltage = memory input - hot at all times
pin 16 = ignition

[Jonazz]

@Jonazz, you have been asked twice to trace the Vout and ground pins of your mystery part. Please help us to help you.

You have the datasheets for the MCU and EEPROM, so you know their Vcc and ground pins. Now use the continuity mode of your multimeter to locate the corresponding regulator pins.

Also measure the voltages coming into the PCB. One of them will be the +12V battery supply.

Sorry i know. i been out town for work. now i have a little time again in this weekend. so im on it.

[Jonazz]

Hi all!

Im super happy for everyone trying to help me!
Im sorry that im so slow. but i been working last six weeks plus weekends.
Im 100% open to send it out in the world for who that want to play with it and analyse it. im paying for the shipping each way plus spare parts!
Who is up for the challenge?

//Jonas

[fzabkar]

Maybe Per Hansson (https://www.eevblog.com/forum/profile/?u=121676) could help you