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Need help identifying crystal on Macintosh IIX board

Verault

Well-known member
I am doing a repair on a macintosh IIx board and the crystal in postion Y1 fell off. all that is stenciled on the side of the crystal is f1 japan or f-japan. I cannot find any schematics for this board. Can someone pleast tell me the value of this crystal so I can source a replacement?
 

Verault

Well-known member
Again I am looking for the value of the Crystal at Y1 on a Macintosh IIx. If anyone knows where I can find a Schematic that would be incredibly helpful. Thank you!
 

desertrout

Well-known member
Just looking at the board, it appears Y1 is the oscillator for the RTC/PRAM, which generally is 32.768kHz. Considering the II board is fundamentally the same as the IIx board, the Bomarc II schematics indicate Y1 as that.
 

Verault

Well-known member
Thats great news Desertrout! I actually have a small baggie of those already from an Apple IIgs board repair I did a couple of years ago.

Now if you can tell me where I can get the SMD 74LS651SG IC's (positions UC7 and UC8) Ill be in great shape to start the repair. I cant seem to find any of these online. Another IIx board I have has them listed as ALS651 or TI 831BF
 

Verault

Well-known member
Id rather find a NOS replacement or alternative. IF I get another MAC II board I will be compelled to fix it...
 

desertrout

Well-known member
I'm certain there are some bombed ones out there that are not fixable and just collecting dust under someone's bench... it's worth asking in the trading post forum. Sometimes it's the only place to find these old parts. But in this case some NOS of these particular chips may surface on eBay in due time.

There appear to be a handful of DIP versions of the 74als651 available on eBay at the moment... if you're really stuck (or in a hurry) you could get or make a couple DIP to SOIC adapters... lol (but also kinda serious)

Sadly this is now an all-too-common problem with our hobby; obsolete parts that die / get harmed and no modern replacements exist.

What happened to yours? Battery leakage?
 

Verault

Well-known member
Yeah, battery leakage on a few of them. I received 2 complete MAcintosh II systems and 2 complete Macintosh IIx systems and one spare Macintosh II board. I fully repaired one MAcintosh II board and one Macintosh IIx board. I have another II board which I have repaired to the point of the startup chime but no futher (its a work in progress). A few have damage by leaky batteries and the rest are damaged by leaking SMD caps which do just as much trace damage. I try and save every system I come by; I like to challenge myself.

I took a gamble and bought these from a seller in Poland: https://www.ebay.com/itm/293876685174

Figure they are faster than the originals but.. should.. work. Maybe.

These systems came from IBM in thier New York Office and have stickers for "R&D" with Hard Drives loaded with Xenix so I was pretty excited to get them.. Until opening them up. But hey they didnt cost me anything.
 
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mg.man

Well-known member
They came from IBM in thier New York Office and have stickers for "R&D" with Hard Drives loaded with Xenix
Wow... Xenix... that's a blast from the past. I worked for IBM back in the late 80s, and we had a Mac in our development lab... not for Xenix, but for (Graphical)UI study... This was before Windoze had "Program Manager" and IBM TopView (tiled, non-overlapping 'windows') was all you had on IBM DOS... Long time ago...

Is there any chance those Xenix drives will boot??
 

Verault

Well-known member
Well you know how old SCSI drives are. I will try and post back. They are 5.25" single height scsi drives so thats an odd size (then again I have a SCSI 2 one Gigabye dual 5.25" monster of a drive working in my IBM 5160 so maybe its not to weird. Weird for a MAC.

If I can get the drive working I was thinking I could do something with Xenix and my TRS-80 Model II when I get that thing working with Xenix as well.
 

Verault

Well-known member
Will do. So many broken traces to repair before even knowing if the logic is working. Now if only somone will make a modern 68040 ( or alternative) cpu upgrade for the Macintosh II that wont break the bank...... I have a portrait monitor and two page display which will pair nicely with these units (yes the cards too). I intend on getting a nice setup with them when I am done.
 

mg.man

Well-known member
Well you know how old SCSI drives are.
Yep... but... I still have several working HD20s and Rodime (also 20Mb) drives... *love* the noises they make!

They are 5.25" single height scsi drives so thats an odd size ... Weird for a MAC.
Not really, I have a H/H 5.25" SCSI drive that came in my II... I believe that one is a Seagate tho...

Out of curiousity... whereabouts are you located? Europe somewhere?
 

mg.man

Well-known member
Why do you ask?
I was curious given your mention of Poland, but also reference to these systems being at IBM NY. Also, I have a "spare" IIx logic board which is not bombed and visually in pretty decent shape - a number of the RAM clips got busted in transport, though, so I've not had the energy to see if I can get it working... I thought we might work out some kind of swap for one of your "big SCSI" drives or internal drive bracket or... So wanted to see what the shipping situ was...
 

ScutBoy

Well-known member
These systems came from IBM in thier New York Office and have stickers for "R&D" with Hard Drives loaded with Xenix so I was pretty excited to get them.. Until opening them up. But hey they didnt cost me anything.

Xenix for Mac? Don't think I've heard of such a thing. Xenix for Lisa, yes...
 

Verault

Well-known member
I was curious given your mention of Poland, but also reference to these systems being at IBM NY. Also, I have a "spare" IIx logic board which is not bombed and visually in pretty decent shape - a number of the RAM clips got busted in transport, though, so I've not had the energy to see if I can get it working... I thought we might work out some kind of swap for one of your "big SCSI" drives or internal drive bracket or... So wanted to see what the shipping situ was...
I just buy things from where I can get them. Those chips are not easily available so I took the chance on what that Polish seller had. As far as a trade I think Ill pass thanks anyway. I dont have enough brackets to go around, same goes for hard drives and again.. If I get another board I will only be compelled to fix it.. even if its missing parts.... I just cant help myself...
 
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