Help to identify IC Supermac 8*24 PDQ

[johnnyilblasco]

Hi guys, I've a faulty 8*24 PDQ, provably is something around U24 or the U24 itself. I can't find anything about this card: schematics, parts list and so on...
The IC is a clk-02 9146 (see the photos), but I dont know what it is. Maybe a clock buffer but I dont know.
Any help ?

Thank you so much

 

[Phipli]

The IC is a clk-02 9146 (see the photos), but I dont know what it is. Maybe a clock buffer but I dont know.

It's a PS047301. 9146 is the date code, 46th week of 1991.

It is a RAMDAC manufactured by Bt.

473 family RAMDACs were pretty common on 24bit cards.

Attached datasheet might not be the exact part, but it is the same family.

 

[cheesestraws]

It's a PS047301. 9146 is the date code, 46th week of 1991.

that's U26, not U24

 

[Phipli]

that's U26, not U24

My bad

I got distracted by the huge RAMDAC in the photo.

 

[johnnyilblasco]

Yes the U24, not the U26...

 

[Phipli]

Its probably the dot clock generator if it is any help.

SuperMac PDQ, Spectrum 8, 24, Thunder ROMs

I have this card, which appears to be a Spectrum 24 IV, but looks very similar to higher end cards. I was wondering if it might just be a Spectrum 24 IV ROM in a higher end card, but it also has an ASSY sticker with 0008235-0001. Here is a closeup on the ROM, and it also has a 40MHz crystal...

68kmla.org

 

[johnnyilblasco]

From a quick check it seems to me that the pinout is not compatible. I don't know if it's because one chip is clk-02 and the other clk-03. But anyway it's a starting point...

 

[Arbee]

That's the dot clock generator. What problem are you having with the card? If it creates a syncable image at all, that chip is doing its job.

By way of speculation, it's likely a remark of something off-the-shelf. Programmable PLLs were pretty new in the early 90s so there weren't a lot of options. Apple used the National Semiconductor DP8531 (Q700/900/950) and DP8534 (Wombat) and the Sierra Semiconductor SC11412 (Q605/LC475/LC575), to give some popular examples.

 

[johnnyilblasco]

At the beginning the card generated a wobbly image which was stabilized by touching the R39 resistor. Now she is completely dead. There was a moment that generated something by holding down the IC. I reworked all the soldering and checked the traces... I probably damaged the IC further by doing some checks on the traces and shorted it out. All the components around are ok...