Performa 475 Video Ram

[clockchip]

Hi,

I bought an recapped Performa 475 from ebay and the mac worked perfect.

So i bought two new 512 Kb video ram modules to extend the graphics capabilities.
Unfortunately after swapping the video memory modules I recognices that the graphic output has some faulty pixels (please refer to the attached picture).



Depending on the resolution the faulty pixels are on different locations at the screen.
Does ths mean the new video memory modules have defect ram soldered on it?

 

[Phipli]

Hi,

I bought an recapped Performa 475 from ebay and the mac worked perfect.

So i bought two new 512 Kb video ram modules to extend the graphics capabilities.
Unfortunately after swapping the video memory modules I recognices that the graphic output has some faulty pixels (please refer to the attached picture).

View attachment 71297View attachment 71298View attachment 71299View attachment 71300

Depending on the resolution the faulty pixels are on different locations at the screen.
Does ths mean the new video memory modules have defect ram soldered on it?

The first thing I'd try is cleaning the contacts. I tend to use contact cleaner on some paper towel, but if you don't have any, alcohol (IPA, not the beer) might do, but give it a good scrub.

Also, spray some contact cleaner in the slots...

Except, the errors do actually look like dodgy VRAM rather than bad contact. Still clean them and the slots first, but if it makes no difference, you might want to return them.

 

[clockchip]

Ok I will try to clean the contacts.

 

[clockchip]

Ok after some unsuccessful cleaning it seems that there is a defect VRAM chip on the memory module.
I will return it and get an replacement.

 

[Phipli]

Ok after some unsuccessful cleaning it seems that there is a defect VRAM chip on the memory module.
I will return it and get an replacement.

That's frustrating - hope you're not out of pocket.

 

[MacKilRoy]

Ok after some unsuccessful cleaning it seems that there is a defect VRAM chip on the memory module.
I will return it and get an replacement.

Where / who did you buy that from? It's likely a bad solder joint between a chip leg and the PCB, making poor contact at random times.

 

[clockchip]

Where / who did you buy that from? It's likely a bad solder joint between a chip leg and the PCB, making poor contact at random times.

I bought it from ebay from a french guy, and he was very nice and he will send me an replacement.
Regarding the bad solder joint i investigated the modules with my microscope and found no issues.

 

[franklyn]

I think the Performa 475 has 512kB Video Ram build in and can be updated to 1MB in total so you can at two 256kB Module ...

 

[Phipli]

I think the Performa 475 has 512kB Video Ram build in and can be updated to 1MB in total so you can at two 256kB Module ...

Unlike the LC 3, the 475 doesn't have any built in VRAM, it's all on SIMMs, so your two options are a pair of 256k or a pair of 512k SIMMs.