Thanks; that's kind of encouraging, I guess.
Does anyone know what type of fuse it is? I can't see any writing on the one I removed from the Mac Plus.
EDIT: Never mind, I realised it is written there - it's 1.6 amp.
Last edited:
Got a tip for us?
Let us know
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
Mac Plus screen repair
- Thread starter daniel-b
- Start date
- Sort by reaction score
Thanks; that's kind of encouraging, I guess.
Does anyone know what type of fuse it is? I can't see any writing on the one I removed from the Mac Plus.
EDIT: Never mind, I realised it is written there - it's 1.6 amp.
MacTech68
macrumors 68020
Note that it is a "Type T" which means it is a delay type fuse. This is the opposite to a "fast" or "quick" blow fuse.
I've overlayed the two pics and it looks like a short occurred between the fuse and the negative pole of the discrete bridge rectifier. I would at least check the four diodes for shorts. The first pic is whilst looking at the solder side, the second pic is looking at the component side.
In the last photo, I've marked the bridge diodes in red. There should be high resistance (infinite) in one direction and low resistance in the opposite direction of each diode. If there is a dead short across one diode (ie zero ohms), then it will need replacement.
Attachments
Last edited:
I tested the diodes.
All four of them showed "1" in one direction, and around 660 Ohms in the other.
Are we good to go?
D.
All four of them showed "1" in one direction, and around 660 Ohms in the other.
Are we good to go?
D.
Last edited:
MacTech68
macrumors 68020
Since none showed the same reading in both directions, the diodes should be OK. I just can't be sure something else might be damaged, however It seems unlikely.
No guarantees though. 😱
Switch mode power supplies are lethal beasts. Please take all possible precautions.
Hi,
I'll put in a new fuse and see what happens. It will take a while to get the right fuse.
Meanwhile, it occurs to me that we still haven't actually found out what's making the screen flicker. When I started the Mac after completing the soldering (and before blowing it up) the problem was still there.
This is a long thread, so here's a recap of what we know:
- The Mac had no video at all when I first turned it on. I hit it and the video returned. At the beginning, the video would come and go until the machine warmed up.
- More recently, the machine has video all the time, however, it flickers until the machine warms up. After that the video seems quite stable.
- By flickering, I mean that lines appear briefly across the screen. This seems to mostly happen at the top of the screen.
Does this sound familar? I am wondering whether one of the following could be responsible:
- the cable between the analog board and the motherboard.
- The connector on the motherboard - The video seemed to stop disappearing altogether after I connected and disconected this.
This can be proven, I think - if I turn on the Mac with the motherboard disconnected, what should I see? I assume it's a blank white screen. If the screen is still flickering, then the problem is in the analog board, if not, then it is either in the motherboard or in the cable.
Also, could it be a grounding problem?
Thanks again for all your help,
Daniel
PS it looks like I'm getting that Quadra 700 I mentioned a couple of weeks ago.
Lil Chillbil
macrumors 65816
Hi all,
I have the appropriate fuse and I'm going to try to revive the Mac Plus later this evening.
I have a question about the insulating card:
Since I don't have the snap rivets mentioned earlier in the thread, I stuck it on with fresh double sided tape. It later occurred to me that this might not be a good idea, since I don't know whether this tape is going to melt or burn up when the Mac gets hot, so I think I am going to completely remove it before attempting to turn the Mac on.
So, temporarily, is it safe to simply lay the card in position without fastening it?
I have the appropriate fuse and I'm going to try to revive the Mac Plus later this evening.
I have a question about the insulating card:
Since I don't have the snap rivets mentioned earlier in the thread, I stuck it on with fresh double sided tape. It later occurred to me that this might not be a good idea, since I don't know whether this tape is going to melt or burn up when the Mac gets hot, so I think I am going to completely remove it before attempting to turn the Mac on.
So, temporarily, is it safe to simply lay the card in position without fastening it?
MacTech68
macrumors 68020
Not if the machine is re-assembled and vertical. The card will drop an inch or two, exposing the top where there is potential for arcing. I can't think of a reliable 'quick' alternative. 😕
Thanks. Looks like I'll just be testing that it works, and then leaving it off till I've sorted it properly.
D.
Hi all,
It works 🙂
Not only did it turn on, it also showed a perfect, stable display. I am not yet sure whether I can take credit for this with my soldering, or whether it had more to do with me giving all the plugs on the analog board a good push . . .
Thanks for all the help,
Daniel
It works 🙂
Not only did it turn on, it also showed a perfect, stable display. I am not yet sure whether I can take credit for this with my soldering, or whether it had more to do with me giving all the plugs on the analog board a good push . . .
Thanks for all the help,
Daniel
MacTech68
macrumors 68020
Hooray! 🙂
and.... phew! 😱
Probably either, since as you're aware, they're both probable.
Hi, I have a similar problem here. I recovered two old macs - a plus and the se fdhd. The second one required some cleaning and HD reformatting and have been working fine since. About the plus. I cleaned it. First time I switched it on - some weird noises and blurred screen. I switched it off. Cleaned again. Switched on and it worked fine - for first couple of minutes till warmed up with a little shaky borders but then fine. Would eject the proper disk so I decide to fix the fdd (or eventually replace it). Then I read a lot about the screen problems and resoldiering🙂 As much as I never made the soldiering chemp - I tried my chances with connectors. Turned it on - no change with the screan - shaky and after a while fine with the question mark. After a couple of days - arrived the metal frames for inside I ordered (the old ones were covered with rust - I cleaned them fine beforehand but simply wanted to get that plus fine on the inside too. Fired it up and... all it does it does is the sound of clicking (no beep on start and the screen black). Most advise is - bad soldiering or eventually bad part & etc. Tried to resoldier what I did befor - no results. I have to admit I did soldiering some 25-30 years ago. Never was good at it. Doesn't seem like I fried anything and doesn't look like an obvious bridge anywhere but I will take some photos tomorrow.
Hope can bring it back to life as the SE one. Both spent some long bad time in very humid environment, probably some basement (maybe some water around). Getting the rust out took a while.
Regards
Adalbert
Hope can bring it back to life as the SE one. Both spent some long bad time in very humid environment, probably some basement (maybe some water around). Getting the rust out took a while.
Regards
Adalbert
MacTech68
macrumors 68020
The clicking sound is indicative of a shorted Switch Mode Power Supply. The SMPS forms roughly half of the analog board.
The short could be anywhere, but there are some likely candidates.
Check the cable that runs from the motherboard to the analog board. It is keyed (ie, one pin is not fitted near one end). If you've managed to plug this cable in offset by a couple of pins, or reversely, this could be the cause.
However, given your description of the initial problem (shaky borders and blurred screen) it could well be a failing/failed flyback transformer, or other component in the horizontal circuit - nasty at best.
Other candidates are the rectifier diodes on the output of the SMPS. These are the two components mounted on large heatsinks adjacent to each-other on the LOWER half of the analog board.
Some clear pics of the component side (top edge especially) and solder side may yield some answers. For instance, if the heatsinks on the top edge of the analog board are blue-ish or purple in color, then the Horizontal Output Transistor is most likely fried but this often points to the FBT as a root cause.
Thank you for a quick replay. I'll inspect that further.
1) Will start with photos - you're right, there is a chance they might possibly point at some causes
2) The only thing that changed since it was working fine (but including shaky screen on warm up) was my soldering - possibly (a) it's my doing (b) coincidence - and sth that was going to break just did anyway (c) both🙂
3) In the meantime - since I had nothing better to do - I replaced the metal frames and the FDD for the one that arrived (plus is not working so didn't check - if I bring plus back to life and new drive is fine I will re-lubricate and clean the old drive (it worked mechanically but kept ejecting disks - the working and tested on SE 800k system disks) and share with those who might need it). That operation didn't obviously have any impact on the plus in terms of solving the clicking mystery.
I will come back with pictures.
ps. for later - I have a multimeter so If guarded right I might test some connections and parts. By guided I mean that I have no skills at that and basic understanding but if told which parameter and which part should be tested should complete that complex operation🙂
1) Will start with photos - you're right, there is a chance they might possibly point at some causes
2) The only thing that changed since it was working fine (but including shaky screen on warm up) was my soldering - possibly (a) it's my doing (b) coincidence - and sth that was going to break just did anyway (c) both🙂
3) In the meantime - since I had nothing better to do - I replaced the metal frames and the FDD for the one that arrived (plus is not working so didn't check - if I bring plus back to life and new drive is fine I will re-lubricate and clean the old drive (it worked mechanically but kept ejecting disks - the working and tested on SE 800k system disks) and share with those who might need it). That operation didn't obviously have any impact on the plus in terms of solving the clicking mystery.
I will come back with pictures.
ps. for later - I have a multimeter so If guarded right I might test some connections and parts. By guided I mean that I have no skills at that and basic understanding but if told which parameter and which part should be tested should complete that complex operation🙂
Last edited:
Here come the photos.
1) Analog/Power board overview
2) Some of my soldering work on connectors:
3) There is a nasty spot around the battery compartment (it didn't get worse, it was that bad before my work too I guess; it's just different but still bad🙂
4) The look at the board side with parts and yoke connection
This much for now
Regards
1) Analog/Power board overview
2) Some of my soldering work on connectors:
3) There is a nasty spot around the battery compartment (it didn't get worse, it was that bad before my work too I guess; it's just different but still bad🙂
4) The look at the board side with parts and yoke connection
This much for now
Regards
Last edited:
MacTech68
macrumors 68020
I'm afraid it doesn't look very good for this analog board. Everywhere on the tracks that you see dark spots (and clusters of spots), means that the copper tracks under the green lacquer are corroding. On thinner tracks, this can eventually etch a break in the track.
For longevity of this board, it needs some serious re-work, perhaps beyond your present skill level.
It would require removing the lacquer on affected copper, gently scraping back to nice shinny copper (rather than dull copper), probably soldering over the copper and even replacing the tracks with pieces of carefully shaped flat wire (often de-soldering braid works well). Also, other solder joints that are dull need to have all the solder removed, solder pads cleaned, the leads of the components cleaned and then resoldered. Finally, a new lacquer can be applied if desired.
It's very tedious work and over-heating tracks can cause bigger problems. Professional kits come with sections of track with solder pads that can be re-fitted.
You may also need to pay careful attention to the trim-pots, as these are not terribly well sealed and could suffer oxidization, causing intermittent jitter.
The fault you originally had could be caused by corroded tracks, corrosion UNDER solder joints (impossible to see with the human eye) or oxidization in the trim-pots.
With this much corrosion, I wonder how the motherboard has fared.
Sorry to be the bearer of bad news, but I wouldn't like to give you false hopes.
Your soldering doesn't appear to have caused any shorts, but when resoldering, it's a good idea to either:
1. remove original solder and apply sufficient heat to the pad and component leg to allow new solder to flow over both ... or...
2. apply sufficient heat to re-flow (melt) the existing solder, and apply a small amount of new solder.
In your case, the first is better, but you need better skills than a beginner to achieve it, and the use of de-soldering braid or a solder sucker.
With a board such as yours, often when removing the solder, you will see a dull copper color underneath. If that's the case, then the pad needs to be gently scraped back to bare copper. In other words, if you CAN'T remove the solder COMPLETELY, the new solder will 'take'. Conversely, dirty or oxidized copper will create a poor electrical join.
Sorry for the long-winded, bad news post. 🙁
Hi, I appreciate the quick response and much of good advise. Basically I plan to get that plus back to life. Not for commercial reasons. What I already put in it I would never get back, except for - hopefully - a smiley mac on startup🙂 I get all you expressed. As it's no art to break another plus to get such board I will simply ask a friend of mine - he knows the art of electronic fights - I mean he's an expert. And pass to him your comments as well.
Get back as soon as I have some news.
Regards
Get back as soon as I have some news.
Regards
Last edited:
Hi all,
In the end I used three very small cable ties to fix the insulator card on. It seems to me that this is a perfect solution: they're plastic, so they're not going to cause a short; they're not going to melt; I can take them off again if I need to, and they fit inside the case.
I tested the computer briefly, and it seems to be working OK. I also installed the new floppy drive, but I haven't tested it yet. It whirred when I turned the computer on so at least it got that far.
The screen is still apparently stable. I'll be testing the computer over the weekend and I'll let you know how it goes.
Thanks again,
Daniel
PS Adalbert, sorry about your dead analogue board 🙁
In the end I used three very small cable ties to fix the insulator card on. It seems to me that this is a perfect solution: they're plastic, so they're not going to cause a short; they're not going to melt; I can take them off again if I need to, and they fit inside the case.
I tested the computer briefly, and it seems to be working OK. I also installed the new floppy drive, but I haven't tested it yet. It whirred when I turned the computer on so at least it got that far.
The screen is still apparently stable. I'll be testing the computer over the weekend and I'll let you know how it goes.
Thanks again,
Daniel
PS Adalbert, sorry about your dead analogue board 🙁
🙂 Appreciate the compassion but... the little fat beige friend of mine woke up!!! As I said that friend I have knows his job well. For now it's working no worse than before. It turns out that I didn't harm it with my work too much. Today I'll have a tube TVs expert (hard to find now) come to see it too. To join in search for the cause of shaky screen on start up (apart from tracks and copper problem). Don't call a win yet, but there's much hope for my plus. When I get the details I will post what exactly happened and what has been done to it.
Regards
MacTech68
macrumors 68020
Sounds like you've got the right people for the job. They might find the following PDF helpful. Just one difference, you have a 240/120V version, which is a minor difference and component overlay numbers are different.
http://68kmla.org/files/classicmac2.pdf
Hi all,
I think I can confirm that everything works in my Mac Plus - I was able to boot from the floppy and the zip drive, and the screen is stable.
Thanks for all the help in the marathon thread.
This is Daniel, signing off . . .
I think I can confirm that everything works in my Mac Plus - I was able to boot from the floppy and the zip drive, and the screen is stable.
Thanks for all the help in the marathon thread.
This is Daniel, signing off . . .
MacTech68
macrumors 68020
Some update on my plus.
So, it's working the way I can turn it on. Actually no special lessons on that. As His Majesty MacTech68 said before - some of the tracks were in a pretty bad condition due to humidity and so. What was done:
1) All the electronic parts on video/analog boards checked - test passed and believe or not all seem to be fine
2) Minor yoke adjustment - didn't realy have much of the impact
3) Minor tracks cleanup (analog board) - only some of them got bad and those were cleaned, optically there is not all of that much of a difference, now all tracks pass the test with one restriction - it doesn't really mean that they may not go bad again. For such all the board would have to be totally reworked, which (in expert's opinion) did not make much sense.
The plus is back home and there is still much to do. I'll basically tell all of the story maybe y'all would have some suggestions. Guess would be better that way than just do sth bad to it🙂
The story. As some may remember initially I observed the shaky screen on startup. And - didn't mention much on that back then - the FDD problem. It would accept disks and eject right away all of them including the very right ones (800K with right system - tested to work fine in othere macs). Let's call it drive "A". I got me another drive, put in and more or less then my last problems accured. When plus returned home - with drive "B" it turned out that it was really "As-is" one and bad, i.e. wouldn't work and make awfull noise (possibly stuck or some part burnt) but the repair didn't cover it and I didn't dig into that either. Drive noise is a noise but... the shaking went away (!?).
Now it gets complicated. I got me a perfectly working external 800k drive. Let's call it "C" - now the combinations:
1) Pulled out drive "C" out of the case and put into plus - keps ejecting exactly as with drive "A" as described above; shaky screen on startup came back
2) Option one + external case with drive "A" in external case - sympthomas as in 1) plus startup from external drive gives - smiley mac for a few seconds and... disk is ejected (?!)
3) Drive "C" in external case, drive "A" in plus - disk with system in external - boots right but has the shaky screen for about 5 minutes; internal ejects disks; the same config but with scsi ribbon unplugged from the internal fdd... the same results (didn't check unplugging from the board yet)
More combinations to go. What's interesting - boots fine on external but with shaky picture. And then no shaky screen with broken "B" drive in plus (making awful noise). Seems like might be something related to board connection - fdd/motherboard or drives themseves. I replaced the ribbon itself - no impact.
This much for now🙂 I'll post pictures of warmed up working plus with system 1.1 on it (off the external drive) later.
Regards
Ok, I tried another combination which I suspected to work fine (based on previous ones):
- Drive "C" in original case as external drive and drive "A" (the original one and faulty) still in a bay but unplugged from the motherboard... And plus boots and there is no shaky screen effect. At any stage, i.e. in the very beginning before the external drive picks up (the grey screen), during boot and over normal work course.
Please correct me if I'm thinking right:
1) the fine working "C" drive didn't work as internal (kept ejecting as original)
2) with internal drive unplugged from the motherboard (which basically means any drive) and the fine working "C" drive in a case as external - everything works fine (boots and no shaky screen)
3) two different ribbons tested with no difference
...
this might be sth related to the FDD drive socket at the motherboard or eventually something further related to FDD at the motherboard controlling the internal drive in particular?
Regards
So, it's working the way I can turn it on. Actually no special lessons on that. As His Majesty MacTech68 said before - some of the tracks were in a pretty bad condition due to humidity and so. What was done:
1) All the electronic parts on video/analog boards checked - test passed and believe or not all seem to be fine
2) Minor yoke adjustment - didn't realy have much of the impact
3) Minor tracks cleanup (analog board) - only some of them got bad and those were cleaned, optically there is not all of that much of a difference, now all tracks pass the test with one restriction - it doesn't really mean that they may not go bad again. For such all the board would have to be totally reworked, which (in expert's opinion) did not make much sense.
The plus is back home and there is still much to do. I'll basically tell all of the story maybe y'all would have some suggestions. Guess would be better that way than just do sth bad to it🙂
The story. As some may remember initially I observed the shaky screen on startup. And - didn't mention much on that back then - the FDD problem. It would accept disks and eject right away all of them including the very right ones (800K with right system - tested to work fine in othere macs). Let's call it drive "A". I got me another drive, put in and more or less then my last problems accured. When plus returned home - with drive "B" it turned out that it was really "As-is" one and bad, i.e. wouldn't work and make awfull noise (possibly stuck or some part burnt) but the repair didn't cover it and I didn't dig into that either. Drive noise is a noise but... the shaking went away (!?).
Now it gets complicated. I got me a perfectly working external 800k drive. Let's call it "C" - now the combinations:
1) Pulled out drive "C" out of the case and put into plus - keps ejecting exactly as with drive "A" as described above; shaky screen on startup came back
2) Option one + external case with drive "A" in external case - sympthomas as in 1) plus startup from external drive gives - smiley mac for a few seconds and... disk is ejected (?!)
3) Drive "C" in external case, drive "A" in plus - disk with system in external - boots right but has the shaky screen for about 5 minutes; internal ejects disks; the same config but with scsi ribbon unplugged from the internal fdd... the same results (didn't check unplugging from the board yet)
More combinations to go. What's interesting - boots fine on external but with shaky picture. And then no shaky screen with broken "B" drive in plus (making awful noise). Seems like might be something related to board connection - fdd/motherboard or drives themseves. I replaced the ribbon itself - no impact.
This much for now🙂 I'll post pictures of warmed up working plus with system 1.1 on it (off the external drive) later.
Regards
Ok, I tried another combination which I suspected to work fine (based on previous ones):
- Drive "C" in original case as external drive and drive "A" (the original one and faulty) still in a bay but unplugged from the motherboard... And plus boots and there is no shaky screen effect. At any stage, i.e. in the very beginning before the external drive picks up (the grey screen), during boot and over normal work course.
Please correct me if I'm thinking right:
1) the fine working "C" drive didn't work as internal (kept ejecting as original)
2) with internal drive unplugged from the motherboard (which basically means any drive) and the fine working "C" drive in a case as external - everything works fine (boots and no shaky screen)
3) two different ribbons tested with no difference
...
this might be sth related to the FDD drive socket at the motherboard or eventually something further related to FDD at the motherboard controlling the internal drive in particular?
Regards
Last edited: