Uncreative Labs

Joined: 27 Jan 2007 Posts: 274 Location: USA

i think i found the issue... aparently the package of ram chips i found wasn't all 60ns, it seems someone slipped in 4 70ns ones too, so i ened up soldering 7 60ns chips and 1 70ns chip Razz

. they all looked the same, but now im gona use the mem chips off the junked pci card

Joined: 27 Jan 2007 Posts: 274 Location: USA

seems like the salvaged ram chips might be messed up, altho it could be my half assed soldering job , one of the mem chips got realyh hot to the touch while the other 7 were not hot at all. should i try esoldering the chips again?
if i cant fix this, how much ya think the 2mb memory module upgrade is worth by its self?

Joined: 27 Jan 2007 Posts: 274 Location: USA

arg, re soldering didn't work, and im loosing traces everytime i redo it. i think its safe to say im not gona use the salvaged chips again..boards all soaked in solder flux now wich looks realy dirty. not sure if i should keep going, i know that the vpu is still good and only issue is getting all the memory chips soldered right.

Joined: 02 Oct 2004 Posts: 594 Location: Western NC

Quote:

and im loosing traces everytime i redo it.

Then it's time to abandon the project. As mentioned, it takes quite a good hand and specialized equipment to do proper SMT soldering...

Joined: 27 Jan 2007 Posts: 274 Location: USA

well im out of ideas, replaced it with 2 sets of mem chips, swaped the vpu from the pci version and im still gettin screen coruption, i think i repaired the rip ram traces with 30 awg kynar wire with the help of a multimeter, the vpu i scrapped of the pci one has pin 7 missing, but it still powered up and displayed some graphics, with was the same screen it had with the other vpu.

there are only 2 ideas that come to mind, the capacitors near the mem chips are overburned from using a heat gun to long over and over, or the Spectra DAC is bugged, i do got a spare DAC too. mabey i should start lookin for a resonalbly priced one for sale that has the 60ns memory so i can use my mem upgrade card on it

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

Wow, I thought I was nuts for trying to reverse engineer a 2mb memory upgrade module, but your efforts are truly impressive. I've swapped SMT chips before, but nothing nearly as complex as the VPU on a Mach64. What kind of equipment are you using to desolder SMT chips? Are you using a blow torch to melt them off, followed by a chemical bath to remove the excess solder?

Is the Mach64 ISA really that rare that you need to go to these lengths? By the time I finished my PCB layouts for my memory module, I had already managed to find one for 5 bucks on ebay.

Joined: 27 Jan 2007 Posts: 274 Location: USA

i is using a hot air gun to desolder smt chips, then i solder the corners of the ram then soldering iron on the ram, then use kynar wire to fix broken traces, for the vpu its self, i desoldered with hot air, solder coners, then with an untinned screwdriver tip i filed my self i pressed on the pins to heat em up, the flux came from the solder i used to clean it up with, by flooding it with solder, then sucking it off, leaving just a little on. i use a 25watt weller if anyones intrested. mabey i should post a pic of it now and a screen shot of it running. just cant figure out whats still broken, could i have burned up the capacitors near the ram or resitors, or is that pin 7 on the salvaged vpu important?(it came l ike this when i got it) is the DAC damaged, i can replace the DAC, an i do got a few more ram chips, but i dont wana solder all the kynar wire again. whole back side looks like a red haired girls armpits with all the red kynar wire. any one sees a cheap mach 64 isa on ebay, let me know, i'll make a ebay acount just for it!

edit: heres a pic of what its now, http://i46.tinypic.com/15qept4.jpg some of u might have seen it before it went belly up

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

If you've already gone to the trouble of replacing the VPU and memory, why not try the RAMDAC and EEPROM too?

Damn, that's an ugly card. What can you expect after what it's been through though. I replaced some memory chips on a VL card recently, and it is also a big mess like yours. I'd never bother with a VPU though, that looks like a serious PITA.

I'll keep an eye out for one. The DRAM version is far more common, but I see the VRAM version every now and then.

Posted: Wed Dec 09, 2009 3:55 am

that poor card, i can see half the traces have went MIA, does the thing still work even?

Joined: 27 Jan 2007 Posts: 274 Location: USA

it actually displays graphics mode, with artifacts tho, im wondering what i should do to it now, try more mem chips/ fix pin 7, swap ramdac, change all the capacitors/resistors near mem/vpu? i know the roms are still good i think

is the samsung km428c256j-6 fully compatible with the OKI m548262-60? cause the samsungs were off the pci card, and the oki's were stock, can i combine them?

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

I'm pretty sure those chips should work fine together. When in doubt, download the datasheets and compare.

Joined: 27 Jan 2007 Posts: 274 Location: USA

its time for plan S, s as in SSOP, the mach 64 also has traces for 512kb ssop vram chips, as seen here http://i45.tinypic.com/2eg41es.jpg, thought id scan it before solding chips on as its probly the only time were gona see a naked mach 64. i found an artist netvison 2000i pci with 512kb ssop 60ns, wich i will replace with 70ns ones so i can use the netvision upgrade card thats 70ns too, the 70ns ones were from a ded pci speedstar 64 video..

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

Looking at your photos almost makes me want to cry. I'm just glad it was already broken.

Those traces are really interesting. I don't think I've ever seen an ISA or VLB version of the card fitted with those chips. It's too bad they didn't provide additional traces on the back of the card so that you could solder on all 4mb without having to use the proprietary expansion module.

Joined: 27 Jan 2007 Posts: 274 Location: USA

if this works, we'l have one thats fitted with ssop, possible the only pics of one too, also, the ssop's dont need me to heat gun it to solder it, so i wont over heat the ssop vrams

Joined: 27 Jan 2007 Posts: 274 Location: USA

well, i installed the ssop's and now the card is acting like there is 0 kbs installed, so im thinking that its missing some of the little capacitors/resistors needed to use this type of ram.. i cant seem to find a pic of a mach 64 with this mem config to compare too, just one pic of a pci one.. this is realy confusing