Title: NextStation Video Problem
Post by: codepoet80 on August 03, 2020, 01:31:37 PM
Post by: codepoet80 on August 03, 2020, 01:31:37 PM
Picked up a NeXTSTation with matching monitor, keyboard and mouse this weekend -- only $250 complete. Seller reported that it worked last time he used it but that it was showing "diagonal lines" when he tested before the sale. I got it home, checked the logic board and clock battery, then fired it up. This is what I got. Image is stationary and stable...just useless.
The world-famous Rob Blessin suggested RAM in a FB discussion, so I cleaned it up with contact cleaner and re-seated half (a full set of 4.) I noticed some white gunk around the RAM slots, but no obvious cap leakage. I do plan to re-cap, but I thought I'd check for signs of life after a bath (a trick that works on Color Classic logic boards that leak.) After thoroughly drying I re-assembled and powered back up -- no change. Same image on the screen. Finally I tried booting without RAM...same thing.
It seems like all of that should at least have changed the symptoms if the problem was on the logic board. Now I'm starting to wonder if the issue is in the monitor. Anyone have any ideas?
The world-famous Rob Blessin suggested RAM in a FB discussion, so I cleaned it up with contact cleaner and re-seated half (a full set of 4.) I noticed some white gunk around the RAM slots, but no obvious cap leakage. I do plan to re-cap, but I thought I'd check for signs of life after a bath (a trick that works on Color Classic logic boards that leak.) After thoroughly drying I re-assembled and powered back up -- no change. Same image on the screen. Finally I tried booting without RAM...same thing.
It seems like all of that should at least have changed the symptoms if the problem was on the logic board. Now I'm starting to wonder if the issue is in the monitor. Anyone have any ideas?
Title: Re: NextStation Video Problem
Post by: barcher174 on August 03, 2020, 01:36:33 PM
Post by: barcher174 on August 03, 2020, 01:36:33 PM
That issue could very likely be the monitor. I've fixed a few that looked like this. Do you see any changes at all on the screen during boot? One way to test would be to split out the vga signal and hook to another screen.
Title: Re: NextStation Video Problem
Post by: codepoet80 on August 03, 2020, 01:50:38 PM
Post by: codepoet80 on August 03, 2020, 01:50:38 PM
OK, I painstakingly ran jumper wires between pins to a VGA cable then connected it to green on a newer VGA monitor. Definitely a hack, but this appears sufficient to prove that the image problem is coming from the computer, not the monitor. Thanks for the suggestion! Alas, there's no change as it boots (or fails to boot) and no amount of key smashing gets the image to do anything different.
So no solution yet, but at least I know where to focus my attention...
Title: Re: NextStation Video Problem
Post by: Scutboy on August 04, 2020, 07:53:19 AM
Post by: Scutboy on August 04, 2020, 07:53:19 AM
Maybe need more than one stick of RAM in that guy?
Title: Re: NextStation Video Problem
Post by: codepoet80 on August 04, 2020, 10:44:16 AM
Post by: codepoet80 on August 04, 2020, 10:44:16 AM
RAM is installed in groups of 4 in this machine, so a minimum configuration is 4 SIMMs and a max is 8. The picture was taken with 0 SIMMs, but tests were done with 4, the other 4, 8 and 0 SIMMs installed, to try to rule out RAM as the issue.
You can read more about supported RAM configurations here: https://www.ding.net/info/next/next3.html
You can read more about supported RAM configurations here: https://www.ding.net/info/next/next3.html
Title: Re: NextStation Video Problem
Post by: barcher174 on August 04, 2020, 02:55:28 PM
Post by: barcher174 on August 04, 2020, 02:55:28 PM
Ok no easy answers from here. 1st thing is to replace the electrolytic caps and give the board a good clean. Does the LED next to the battery blink?
Title: Re: NextStation Video Problem
Post by: codepoet80 on August 04, 2020, 07:55:58 PM
Post by: codepoet80 on August 04, 2020, 07:55:58 PM
As mentioned, the board has been cleaned, and I do plan to re-cap. Everything powers up -- the fan, the LED, the hard drive and the floppy. A clean and steady 12v can be read from the 12v pins on the video connector.
What I've done so far should have had some effect -- leaving me convinced that a significant chip has failed. Fortunately, Rob Blessin has a replacement logic board winging its way to me. As grateful as I am for his assistance, it appears he has a lonely job as the only remaining source of expertise and parts for these computers!
Once I have a working board to compare to, I'll start a more methodical replacement of parts on the failed board until I can narrow it down. If it is a cap, it would be nice to know which one results in this particular symptom -- this failure mode appears to be undocumented anywhere on the Internets.
What I've done so far should have had some effect -- leaving me convinced that a significant chip has failed. Fortunately, Rob Blessin has a replacement logic board winging its way to me. As grateful as I am for his assistance, it appears he has a lonely job as the only remaining source of expertise and parts for these computers!
Once I have a working board to compare to, I'll start a more methodical replacement of parts on the failed board until I can narrow it down. If it is a cap, it would be nice to know which one results in this particular symptom -- this failure mode appears to be undocumented anywhere on the Internets.
Title: Re: NextStation Video Problem
Post by: codepoet80 on August 20, 2020, 09:28:45 AM
Post by: codepoet80 on August 20, 2020, 09:28:45 AM
Replacing the logic board did the trick, which narrows the problem down to...something on the logic board (but not the RAM, since that tested fine on the new board.)
I'm happily up and running now, and have ordered some parts so I can setup a SCSI2SD. Thanks again to Rob for selling me a compatible SCSI optical drive -- I cobbled together a way to connect it via an old Mac Plus hard drive enclosure (3rd party, not Apple original). See pictures.
I'll eventually re-cap the old logic board to see if I can narrow down the problem further. At the moment I have a backlog of Macs that need to be serviced and sold...
I'm happily up and running now, and have ordered some parts so I can setup a SCSI2SD. Thanks again to Rob for selling me a compatible SCSI optical drive -- I cobbled together a way to connect it via an old Mac Plus hard drive enclosure (3rd party, not Apple original). See pictures.
I'll eventually re-cap the old logic board to see if I can narrow down the problem further. At the moment I have a backlog of Macs that need to be serviced and sold...
Title: Re: NextStation Video Problem
Post by: codepoet80 on September 14, 2020, 10:24:09 AM
Post by: codepoet80 on September 14, 2020, 10:24:09 AM
Here's my restoration journal entry:
https://www.jonandnic.com/2020/08/21/nextstation/
Check out my other projects while you're there!
https://www.jonandnic.com/2020/08/21/nextstation/
Check out my other projects while you're there!
Title: Re: NextStation Video Problem
Post by: BillAnderson on September 22, 2020, 07:56:44 AM
Post by: BillAnderson on September 22, 2020, 07:56:44 AM
Quote from: codepoet80 on September 14, 2020, 10:24:09 AMhttps://www.jonandnic.com/2020/08/21/nextstation/
Check out my other projects while you're there!
I like your article on ditching the news algos.
Title: Re: NextStation Video Problem
Post by: rbz on September 22, 2020, 12:24:54 PM
Post by: rbz on September 22, 2020, 12:24:54 PM
Quote from: codepoet80 on September 14, 2020, 10:24:09 AMHere's my restoration journal entry:
https://www.jonandnic.com/2020/08/21/nextstation/
Check out my other projects while you're there!
Great posts in the retro museum!