Thread
Another "Ticking" Macintosh Plus ED
Hello!
I recently scored three ED Macs, two Macintosh Plus EDs and a Macintosh ED (which is a 512ke).
The Mac ED only needed a quick reflow of the J1 connector.
The first Plus ED produced a very quick ticking noise no matter if the logic board was connected or not. I quickly noticed that the flyback diode was shorted. I replaced the flyback, the diode and the transistor and now it is working perfectly as well!
The second Plus is driving me crazy: it has a slower ticking noise, I don't think it is coming from the speaker.
The flyback seems in good shape, I swapped it with a NOS one and it still has the same issue. Did some other measurements on various diodes (according to Pina's books) and they all look fine. I also replaced two capacitors and the optocoupler.
If I disconnect the logic board the ticking gets a bit faster. After heating up the board, I was able to briefly stop the ticking, but still no chine and no video. I measured the +12V line and it was about 15V, the trimmer on the analog board does absolutely nothing. +5V is also way too high, about 6.5V. After taking the measurements I removed the logic board and tested it in the other Plus and it survived he high voltages. I also noticed that somebody clipped the third lead (output) of the 79045 regulator. maybe the power supply killed it (but it is used only for the serial ports, which I don't need).
There is very little dust inside, the HV area looks very clean, so it's possible that it broke when it was still in use (I got it from an Apple Dealer)
The analog board is the 220V INTERNATIONAL model with the W12 jumper removed.
I think there is an open/shorted component in the power supply area, but I cannot find it!
I recently scored three ED Macs, two Macintosh Plus EDs and a Macintosh ED (which is a 512ke).
The Mac ED only needed a quick reflow of the J1 connector.
The first Plus ED produced a very quick ticking noise no matter if the logic board was connected or not. I quickly noticed that the flyback diode was shorted. I replaced the flyback, the diode and the transistor and now it is working perfectly as well!
The second Plus is driving me crazy: it has a slower ticking noise, I don't think it is coming from the speaker.
The flyback seems in good shape, I swapped it with a NOS one and it still has the same issue. Did some other measurements on various diodes (according to Pina's books) and they all look fine. I also replaced two capacitors and the optocoupler.
If I disconnect the logic board the ticking gets a bit faster. After heating up the board, I was able to briefly stop the ticking, but still no chine and no video. I measured the +12V line and it was about 15V, the trimmer on the analog board does absolutely nothing. +5V is also way too high, about 6.5V. After taking the measurements I removed the logic board and tested it in the other Plus and it survived he high voltages. I also noticed that somebody clipped the third lead (output) of the 79045 regulator. maybe the power supply killed it (but it is used only for the serial ports, which I don't need).
There is very little dust inside, the HV area looks very clean, so it's possible that it broke when it was still in use (I got it from an Apple Dealer)
The analog board is the 220V INTERNATIONAL model with the W12 jumper removed.
I think there is an open/shorted component in the power supply area, but I cannot find it!
Wow man, are you making good $$ from all these score's + repair work you have been doing?
Well, most of the times I end up keeping the machine rather than selling it. So far I have 173 Apple devices scattered around my house and my grandparents garage.
As for repairs, I usually invest the money I earn in more (mostly broken) Apple Computers or Arduino/Raspberry Pi stuff.
Is the ED hard to find outside Europe?
As for repairs, I usually invest the money I earn in more (mostly broken) Apple Computers or Arduino/Raspberry Pi stuff.
Is the ED hard to find outside Europe?
Yes.
I actually have a Plus I just picked up that's making a slow ticking noise too. Is that something that I should be concerned about?
That's my kind of solution.
ferrix probably needs to turn the 5v cut out down.
The trimmer on the analog board does absolutely nothing. I desoldered it and it checks fine.
How do you control the +5V cut out? all of the feedback/control is done on the +12V rail.
Soon I'll check some diodes and the SCR, maybe one of them is open/leaky
How do you control the +5V cut out? all of the feedback/control is done on the +12V rail.
Soon I'll check some diodes and the SCR, maybe one of them is open/leaky
In my case, it is R59, but it does absolutely nothing, no matter if it is all the way to one side or to the other, the voltages still remains the same
then that is a problem...
Sure is!
checked most of the diodes and transistors, none of them are shorted or very leaky.
at this point, I'm quite sure there is an open circuit somewhere
checked most of the diodes and transistors, none of them are shorted or very leaky.
at this point, I'm quite sure there is an open circuit somewhere
Sure you changed all the caps, right? please say yes.
I've changed only a couple of capacitors (the ones after the two diodes), I don't have the rest of them in stock. I'll place an order soon.
out of the 5 or 6 ABs I've repaired, none of them had capacitor-related problems. They all had a mix of: broken joints, bad optocoupler , shorted diodes or flybacks. usually I recap them when I see wobbly video or random resets. I've never fixed a board with a recap only
out of the 5 or 6 ABs I've repaired, none of them had capacitor-related problems. They all had a mix of: broken joints, bad optocoupler , shorted diodes or flybacks. usually I recap them when I see wobbly video or random resets. I've never fixed a board with a recap only
yeah change the caps. they are a huge problem with these A/B.
But usually when a capacitor is shorted/leaky, the DC voltage is lower than it should be.
If a capacitor is open I will get loads of ripple on the rail, but I've never seen an electrolytic capacitor go open.
Also, I noticed that the Boards in the 128K/512K don't have as many problems as the ones inside the Plus, they are the same exact board (as far as I can tell) but with older components. Maybe Apple decided to use lower quality parts for mass producing the Plus.
If a capacitor is open I will get loads of ripple on the rail, but I've never seen an electrolytic capacitor go open.
Also, I noticed that the Boards in the 128K/512K don't have as many problems as the ones inside the Plus, they are the same exact board (as far as I can tell) but with older components. Maybe Apple decided to use lower quality parts for mass producing the Plus.
Optoisolator, or its loop filter network.
I did replace the Optoisolator with a brand new CNY17-3, which worked perfectly in the other ABs I've repaired.
Where is the filter network?
Where is the filter network?
yeah get on those caps, sometimes they look great and the lead on the inside is completely burnt up… i'v seen that bunches of times now.
i think its a bad resistor. the same thing happens with the focus pot. if the resistor is bad turning the pot does nothing.
i think its a bad resistor. the same thing happens with the focus pot. if the resistor is bad turning the pot does nothing.
If I power the machine with a Variac, I can get it to provide the correct voltages without ticking or going into protection, the voltage control trimmer lets me adjust (not by much) the output voltage.
But there is no chime, video or sound. The logic board is good as I've tested it in the other Plus ED, and I am measuring the voltages from the floppy port, so they are definitely getting there.
But there is no chime, video or sound. The logic board is good as I've tested it in the other Plus ED, and I am measuring the voltages from the floppy port, so they are definitely getting there.
Actually, the mac chimes and boots (using an external speaker and hard drive). So this board has no audio and no video + unregulated power supply.... Great!
At this point, I think I'll take a look at the video section (the flyback is new).
As for the sound, I don't think there is much on the AB, the only thing that could fail is the speaker (I can steal one from a dead Mac Classic or a dead SE/30)
EDIT: actually, maybe "no video" is caused by the fact that there is not enough voltage for the oscillator to start, so no voltage coming from out of the flyback
EDIT 2: Yup!, I should have +30V on C14, but I only have about +5V
At this point, I think I'll take a look at the video section (the flyback is new).
As for the sound, I don't think there is much on the AB, the only thing that could fail is the speaker (I can steal one from a dead Mac Classic or a dead SE/30)
EDIT: actually, maybe "no video" is caused by the fact that there is not enough voltage for the oscillator to start, so no voltage coming from out of the flyback
EDIT 2: Yup!, I should have +30V on C14, but I only have about +5V
The speaker tested fine, so I swapped the main logic board cable and...
It also brought sound back!
Now I can power the machine without the Variac and it chimes perfectly!
At this point, I need to find new contact clips for the cable and them it's ready to go!
Oh, and also get rid of those scan lines (they only appear when the brightness is all the way up)
It also brought sound back!
Now I can power the machine without the Variac and it chimes perfectly!
At this point, I need to find new contact clips for the cable and them it's ready to go!
Oh, and also get rid of those scan lines (they only appear when the brightness is all the way up)
I cleaned and bent back pins in the connector, adjusted the cut-off and... Done!
Now I only need to find some ROMs for it
Again, out of all of the ABs I've repaired, I've never found one that needed new capacitors (I haven't fully recapped this yet, just swapped two caps)
Now I only need to find some ROMs for it
Again, out of all of the ABs I've repaired, I've never found one that needed new capacitors (I haven't fully recapped this yet, just swapped two caps)
you mean out of the five analog boards you have repaired...
lol..
what a guy....
lol..
what a guy....
Yes!, But I've also seen (here in Italy) lots of listings for fully working machines. My Macintosh 128K works perfectly and it has never been repaired (still has the original double-sided sticky tape holding the vinyl cover to the AB). Maybe the International version of the board is slightly more rugged than the US model.
On the other hand, I've never seen a Mac LC or SE/30 with good capacitors on its logic board.
On the other hand, I've never seen a Mac LC or SE/30 with good capacitors on its logic board.