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PB1400: Restored, worked perfect, now this...

LaPorta

Well-known member
So last night, I went to fire up my 1400. A little preface: I fully recapped and restored this a few months ago. New PRAM battery, rebuilt the main battery, and have been moving onto PSU recap and repair. Installed IDE to SD. Works perfectly.

So, I used it last on Sunday to copy a Bolo map to another machine. I left it shut down since then. Last night, after replacing the capacitor in it's floppy drive, I started it up, and this is what happened:


I have no idea why the screen fades out from the center at startup. Is something fried? You can see from the image that is there that there is a video signal, and that the machine otherwise works fine...the extensions scroll, when the machine is on, I can move the move the mouse. I can hit the power button as at the end to shut the machine down. So, it is something definitely video based. The question is: is it the screen and related boards, a connection issue, or the video circuitry on the main logic board? Any suggestions would be helpful.
 

LaPorta

Well-known member
I did a little investigating and have some more to report. I forgot to include something else: the floppy drive no longer works. I tested another floppy drive module in there as well, and it is just as dead. Tried my known-good CD-ROM drive in there and, while it blinks the orange light, the drive does not spin. A few weeks past, every so often, the floppy drive would spin up out of nowhere and then proclaim that the disk in the drive needed to be initialized...when there was no disk. The sensor switches seem fine so I don't think that is it. Could all these be related, since the floppy drive issue went from an annoyance to it not working at all in the same time frame the screen went kaput? When the machine is up and running, the shadows that are on the screen see to indicate that it is basically showing a part of the top left of the screen, but it is all very distorted and way out of proportion. If I had a better handle on how all this circuitry was interrelated, I might be able to figure it out, but as it is I do not know much.
 

LCARS

Well-known member
I am not an expert on hardware faults but I'll toss in my two cents. The graphical issue seems in part to be caused by a problem with the ribbon cable. Those lines have been the give away for me in the past when a ribbon cable has been torn or shorted.

As for the other issues, I think it a must to check the new caps and see if one has any noticeable signs of failure. My thoughts go to the floppy capacitor as the place to start for the other issues.

Years ago, I left a recapped Newton 2000 plugged in overnight. One capacitor didn't settle in well and blew causing some very strange issues.
 

CircuitBored

Well-known member
The graphical issue seems in part to be caused by a problem with the ribbon cable.

The 1400 series doesn't use ribbon cables for the display so they're not likely to be the cause of trouble for this model. @LaPorta It might be worth checking the continuity on the video cables and connectors anyway.

It seems more likely that either your display panel has failed or your display's power supply has failed. Did you replace the caps in the display when you recapped the rest of the machine? Is it at all possible that you shocked the LCD somehow while doing some other work on the PowerBook? Low LCD voltage could potentially cause this kind of erratic behaviour. You should check that your supply is outputting a the correct voltage and continues to do so while under load. How did you select the capacitors you used for the recap? You could also check the voltage being sent to the LCD from the logic board - I'm trying to recall which pins are which and will update accordingly if I remember.
 

LaPorta

Well-known member
Thank you very much for that. The recap/overhaul was done a good 3 or so months ago, and the machine has functioned without issue. I replaced all electrolytics on all the display panel boards as well. Darn this site outage...I had an entire thread documenting the entire thing with photos...I'll have to recreate it. It is possible something became loose or disloged in there. One thing I was going to try and do is pop the video out board into the machine and see if the video is just fine there (which I assume it to be). Then, I guess I am looking at my screen boards in the display half of the machine. Still wouldn't explain the floppy issue, though.it is always possible that I messed somethig up. It is also possible the power supply I just recapped and repaired is doing something funky that messed something in there up...but again the floppy issue predates that PSU recap. I do know the PSU seemed to work just fine, powering the machine and charging the battery previously.

Here is a list of the caps I used for the recap. This was February, so don't quote me on exactly what went where (I have written notes for that):
 

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LaPorta

Well-known member
So, here is a bizarre turn of events. I opened it up, disconnected the display cable cover, then thought: "well, I have this display card in a bag, might as well hook it up and see if I can get any video on there to troubleshoot if the display is the issue." Turn the machine on to test, and:

1400 Screen.jpg

It works 100% fine without any issue whatsoever. So, that leaves me with many questions, obviously:

1. What in the heck caused the weird video issue? Strain on the video and inverter cables that I stopped when I took off their cover?

2. Though the floppy drive isn't working properly (looks like a mechanical issue) it IS now actually trying to read the disc instead of doing nothing. What could explain that if the issue was with the display cable?

3. If it was not either of the two, could there have temporarily been an issue with the machine by having it connected to the power adapter I recapped? What could actually cause a temporary issue like that that disappears after leaving the machine alone for about a week or so?

I have no good answers, though I am glad that the machine seems to be working well otherwise now. Obviously, I would feel much better if I new just what the heck happened and how to stop it from happening again. It does lead me to suspect that the issue is with the logic board and NOT the screen/inverter, thankfully, because working on the screen is painful.
 

LaPorta

Well-known member
Second update: it appears my floppy drive does't work for some reason, BUT there is another drive I tested in another 1400 I have that works...but it does not in this 1400. So, I have taken the top case off and am looking into if anything looks amiss.
 

LaPorta

Well-known member
I reflowed my capacitor work there, and also checked them with my ERS, and they work fine. Still, the floppy is not working properly. Not sure I understand it. Is it the end of the world? No, not at all. Still...I hate things not 100% working!

Edit: CD drive works, and I know that uses a different connector in there. Very bizarre...

Oh well, I am planning on rebuilding a second battery...I can just hold it in that side I guess!
 

CircuitBored

Well-known member
Thanks for updating this thread. This is extremely strange.

What in the heck caused the weird video issue? Strain on the video and inverter cables that I stopped when I took off their cover?

This seems somewhat plausible but obviously wouldn't explain all this weirdness being set off by you recapping the floppy drive. There was definitely something going on with your screen's inverter. I guess the only thing to do now is keep using the machine and report back if anything changes again. If it works forever we can chalk it up to "just 1400 things" - it's a system with quirks, for sure.
 

LaPorta

Well-known member
Ok, this happened to me again out of nowhere. I was able to attach the machine to the external monitor again, and the monitor works, so I can rule out video system issues: the issue has to be with either the connectors to the monitor or the monitor itself. My best guess is that it probably has to do with the cable/connector to the logic board. Why? Because it seems like the vertical information is missing somehow. I will take a look at this by disassembly soon and report back. Anyone else have any ideas, please feel free to chime in.
 

LaPorta

Well-known member
I found the issue: one of the tiny display wires was almost microscopically pierced by the screw that holds the front screen plastic bezel to the frame. If I hadn’t seen the screw piercing the friction tape, I wouldn’t even have known to look there. It was the pink wire, if anyone knows what signal runs though there. Basically, the signal was grounding off. New friction tape wrapped thicker, just managed to squeeze it in there behind the screw mount. Works fine now!
 

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