PowerBook 3500 video repair

[Sideburn]

Hi all,

Can someone point me to the VRAM on this 3500 board? On the Mack of the board there are four
V53C16258LT50 chips and the datasheet I found for these says they are 256K X 16 so that would mean 1MB. These are also sitting next to the vga connector and video display connector so I’m suspecting this is the VRAM

Do I need to be concerned with the LT50 if I can source these ram chips out? I’m having no luck finding LT50 but I am finding HK50.

V53C16258 Datasheet, PDF

V53C16258 Datasheet. Part #: V53C16258H. Datasheet: 556Kb/20P. Manufacturer: Mosel Vitelic, Corp. Description: HIGH PERFORMANCE 256K X 16 EDO PAGE MODE CMOS DYNAMIC RAM OPTIONAL SELF REFRESH. 45 Results. Part #: V53C16258HK25. Datasheet: 556Kb/20P. Manufacturer: Mosel Vitelic, Corp.

www.alldatasheet.com

Also on the back are two KM416V4104AS and the datasheet I found says those are 4MB so that would be 8MB total. Assuming this is the standard ram.

KM416V4104 Datasheet, PDF

KM416V4104 Datasheet. Part #: KM416V4104B. Datasheet: 806Kb/36P. Manufacturer: Samsung semiconductor. Description: 4M x 16bit CMOS Dynamic RAM with Extended Data Out. 3 Results. Part #: KM416V4104C. Datasheet: 808Kb/36P. Manufacturer: Samsung semiconductor.

www.alldatasheet.com

 

[Sideburn]

Nevermind about the LT50 vs HK50. I figured out they are completely different.

Does the 3400 board have the same VRAM chips as the 3500? If so I will source out a 3400 parts board to salvage them from.

Thanks any help.

 

[CircuitBored]

Nevermind about the LT50 vs HK50. I figured out they are completely different.

Does the 3400 board have the same VRAM chips as the 3500? If so I will source out a 3400 parts board to salvage them from.

Thanks any help.

The 3500 uses a much faster video controller than the 3400 so I would be surprised if they used the same VRAM. I can't say for sure, though. The 3400 and 3500 are essentially the same architecture constructed with different specification components so there's not as much interchangeability as you might think.

 

[Sideburn]

Ok that’s why I was holding off on buying a doner 3400. Well shoot. Sourcing out the video ram is looking impossible. Do you know which rams are the vram on the board? There’s ram on the top and two sets on the bottom of the board.

I’ll have to try and find a doner 3500 board.

 

[3lectr1cPPC]

What video chip does the Kanga use? If one of those RAM banks is physically next to it on the board, I'd expect that to be the VRAM.

Both the 3400 and the Kanga have 2MB of VRAM. The 3400 uses the Chips & Technologies 65550.

To anyone with a Kanga - you can check what GPU it has by going into the System Profiler on Mac OS 8.5 or above, click on the tab that shows all connected drives, then there should be a drop down for video.
Annoyingly, spec sites all just say "None" which obviously isn't true.

 

[Sideburn]

These are the ones closest to the video output:



But the datasheet says they are 256k x 16. Wouldn’t that be 1MB?

V53C16258 Datasheet, PDF

V53C16258 Datasheet. 154Kb/20P. Part #: V53C16258LT45. Manufacturer: Mosel Vitelic, Corp. Description: HIGH PERFORMANCE 3.3 VOLT 256K X 16 EDO PAGE MODE CMOS DYNAMIC RAM OPTIONAL SELF REFRESH. 45 Results. Part #: V53C16258LT50. Datasheet: 154Kb/20P. Manufacturer: Mosel Vitelic, Corp.

www.alldatasheet.com

I am guessing that this is bad VRAM:

 

[3lectr1cPPC]

Did this one have battery damage? If so, the battery is right next to the video out. Could easily be a bad trace or other connection somewhere I"d imagine if that was the case.

 

[3lectr1cPPC]

I just had someone with a Kanga confirm that it also uses the same Chips & Technologies 65550 video card. As such, I can't see any reason why a 3400 board wouldn't work as a donor.

 

[Sideburn]

Not that I can tell. The battery looks ok there was a little bit of white corrosion on it but not much and the board looks ok.

 

[Sideburn]

I just had someone with a Kanga confirm that it also uses the same Chips & Technologies 65550 video card. As such, I can't see any reason why a 3400 board wouldn't work as a donor.

Do you know where the video memory is on the board?

 

[3lectr1cPPC]

That's the video chip so I'd assume the RAM to the right of it is the VRAM.

 

[3lectr1cPPC]

Also - now that I think of it, would you mind if I used the photos of the motherboard on my website? Would be useful to add to Kanga documentation when I get to it.

 

[Sideburn]

Also - now that I think of it, would you mind if I used the photos of the motherboard on my website? Would be useful to add to Kanga documentation when I get to it.

Not at all I could clean the board and take some better photos tomorrow in daylight.

 

[Sideburn]

View attachment 70640
That's the video chip so I'd assume the RAM to the right of it is the VRAM.

That’s what I suspected but the size doesn’t seem to pan out. 256k x 4 = 1MB ?

And these are impossible to find.

 

[Hunter259]

I'm now questioning my own repair on a 3400c. It has two 256K x 16 chips next to it's 65550. Does the 65550 have it's own internal memory?

 

[3lectr1cPPC]

Not at all I could clean the board and take some better photos tomorrow in daylight.

Sure, if you'd like. And thank you!

I'm now questioning my own repair on a 3400c. It has two 256K x 16 chips next to it's 65550. Does the 65550 have it's own internal memory?

I've got no clue about that disparity.

 

[Hunter259]

That’s what I suspected but the size doesn’t seem to pan out. 256k x 4 = 1MB ?

And these are impossible to find.

According to the datasheet you have 2MB. 256K x 16 is in words not bytes. Double the 256 to get the byte total. Unless I'm mistaken.

https://www.versalogic.com/wp-content/themes/vsl-new/assets/resources/support/pdf/65550.pdf

 

[Sideburn]

ok so the 3400c board has Two of the 4 I need then? tempting to buy one on FLEEE BAY then...

 

[3lectr1cPPC]

Both have 2MB of VRAM so why would the 3400 only have 2 of the 4?

 

[Hunter259]

Mac Gurus and Low End Mac report the 3400c as having 1MB and based on the board layout that makes sense. To say I'm a bit confused would be an understatement.

ok so the 3400c board has Two of the 4 I need then? tempting to buy one on FLEEE BAY then...

The 3400c uses different pin spacing from the kanga so it's unlikely to be able to use them.