PowerBook 500 series logic board revisions. How many differences ?

[demik]

Hello,

This thread is mostly documentation. While probing on my lab board, I noticed that there is multiple revisions of boards around with major differences.
Is this something known ?

Having some minor revisions around is a common thing, but there it seems that there is a lot more going on in this series.
So far I've found the following differences

820-0456-B
- dated 1993, 1994
- has a Crystal CS4216 Audio Codec (same series used in a lot of beige PPCs)
- all of the components are on the bottom where the floppy drive is
- video memory is using TSOP II-40 chips, mostly on the bottom
- has ground pads for the floppy carrier on the PCB
- some were labelled 661-0054 "REV A"

820-0550-A
- dated 1994
- has an ASCO 2300 Audio Codec, which I believe is the one called "Singer" used in 660AV and 840AV Macs
- components are on both sides where the floppy drive is
- video memory is using SOJ-40 chips, top and bottom due to space issues
- doesn't have ground pads for the floppy carrier on the PCB
- some were labelled 661-0108 "REV B"

Other visible differences
- different battery management circuit
- due to different audio codecs, the sound support circuitry is different as well (except the excalibur op amp)
- the resistor pack layout for the LCD circuit is different
- most of the components, even if identical do have a different number

If you want to play the game, here is two pictures :

What's the reason for such differences ? Different OEMs ?

 

[aladds]

Could be all sorts of reasons, from unobtainable parts to cost reductions or maybe even the earlier versions have issues with the PPC upgrade or something like that.

I could believe that there also might have been a shift of suppliers who gave much better prices in bulk - if you can use a single Audio IC across all of your products that can be considerably cheaper (with the caveat that you are reliant on a single manufacturer)

 

[Byrd]

The Powerbook 550C motherboard is silkscreened as such, but I don't think it has any difference maybe apart from a slightly different RAMDAC or video chipset for the different LCD?

 

[demik]

I could believe that there also might have been a shift of suppliers who gave much better prices in bulk - if you can use a single Audio IC across all of your products that can be considerably cheaper (with the caveat that you are reliant on a single manufacturer)

That crossed my mind, except they used the ASCO Codec in the later revision, which is the IC that was "caned". Fair enough on the first part.

Could it be an US vs EU production as well ? I've always got hand on rev A boards over here. What do you guys have on the other side of the pond ?

The Powerbook 550C motherboard is silkscreened as such, but I don't think it has any difference maybe apart from a slightly different RAMDAC or video chipset for the different LCD?

Interesting, any pictures ? I believe the only difference is in the CPU board (LC040 vs full 040)

 

[Durosity]

The Powerbook 550C motherboard is silkscreened as such, but I don't think it has any difference maybe apart from a slightly different RAMDAC or video chipset for the different LCD?

I have a prototype PowerBook 550c, and the logic board in it is a stock one from a 540c (I think from memory it’s a rev A.. I’m guessing when they made it they just took an existing 540c they had sitting around and replaced a few components), and the video works fine on that one.

 

[jeremywork]

The three variants I've seen are 820-0550-A, 820-0615-A, and 820-0709-A (550c).

 

[demik]

The three variants I've seen are 820-0550-A, 820-0615-A, and 820-0709-A (550c).

View attachment 90249View attachment 90250View attachment 90251

Very insignful thank you! Looked a lot of them and didn't find anything really major. Guess the biggest difference is between

Found a dead 820-0615-A over here and it has the ASCO sound chip whereas yours are the CS4216 one. Reading through both data sheets, it seems that there they do have some common pins and control modes, so sort of pin compatible.

I have a prototype PowerBook 550c, and the logic board in it is a stock one from a 540c (I think from memory it’s a rev A.. I’m guessing when they made it they just took an existing 540c they had sitting around and replaced a few components), and the video works fine on that one.

Nice! That's my understanding as well, the difference is mostly the CPU board.

 

[croissantking]

Adding photos of my 820-0456B into the mix. This is an early revision board.

The two OS-CON caps and battery charging contacts have been removed from this example.



Here's a reference for the two caps (taken before removal).