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No video output on Apple Lisa 2/Macintosh XL

Brokoli1

Member
Hello all,

I am a proud owner of an Apple Lisa 2/Macintosh XL since 2 months. Before turning it on for the first time, I replaced ALL the capacitors.
Now I have the following problems:

1. no video, CRT completely dark. I got a videoboard sent to me by another collector, with this it works fine.
Now the question is what is defective in my videoboard? The caps are all new. What components are known to fail?
I unfortunately do not have an oscilloscope...

2. the 25MB SUN Remarketing HDD does not spin and flashes 3x slow, 3x fast. I have tried to turn this on manually, still it will not start. I have replaced the capacitors on the HDD board and the controller board. However, I know that old hard drive and especially MiniScribe are very likely to fail and can not be repaired.

3. a ProFile 5MB was also included. The self test completes without any problems. But as soon as I connect a parallel cable the LED is on and the check does not start.
I bought this cable from Amazon:

Thanks in advance for the support
 

stepleton

Well-known member
Hi @Brokoli1 .

1. Did the video board work before the recap? If so, you should probably inspect your work very closely and check that there aren't errors. As you have two video boards, you may be able to compare one against the other.

If not, even though there's no picture, do you have high voltage? Can you feel static electricity on the face of the CRT? When the Lisa turns off, do you see a flash?


2. I don't really know for SunRem hard drives and can't really offer advice about them. Someone over on lisalist2.com might know more.


3. Do I understand correctly that the ProFile refuses to do the self-test whenever it connects to a Lisa that's off? If so, I've seen this happen before. Try starting the Lisa and see if the ProFile begins the self test. If it works, the Lisa may try to boot from the ProFile and fail because the ProFile is busy self-testing, but just wait --- once it's done, you can click STARTUP FROM and select the ProFile from the menu.
 

mg.man

Well-known member
I bought this cable from Amazon:
You need to remove pin 7 from one or both ends - just break it off.
 

Brokoli1

Member
Hi @Brokoli1 .

1. Did the video board work before the recap? If so, you should probably inspect your work very closely and check that there aren't errors. As you have two video boards, you may be able to compare one against the other.

If not, even though there's no picture, do you have high voltage? Can you feel static electricity on the face of the CRT? When the Lisa turns off, do you see a flash?


2. I don't really know for SunRem hard drives and can't really offer advice about them. Someone over on lisalist2.com might know more.


3. Do I understand correctly that the ProFile refuses to do the self-test whenever it connects to a Lisa that's off? If so, I've seen this happen before. Try starting the Lisa and see if the ProFile begins the self test. If it works, the Lisa may try to boot from the ProFile and fail because the ProFile is busy self-testing, but just wait --- once it's done, you can click STARTUP FROM and select the ProFile from the menu.
Hello stepleton and thank you for your reply.

1. I have not turned on the Lisa before cleaning and replacing the caps (precaution because expensive device). I have absolutely no high voltage, CRT remains completely dark. However, the cathode lights up. I measured and compared the resistances of the transistors and the BU406 had completely different values. This I will now replace and test. This is probably responsible for the horizontal deflection...

The ProFile also does not make a self test, even if the cable is only plugged into one side of the ProFile. I have now ordered a new cable and will test it again. I had removed pin 7 before.
 

Brokoli1

Member
You need to remove pin 7 from one or both ends - just break it off.
Yes, i did this before. I bought a new one and will test this today.
 

mactjaap

Well-known member
Hi @Brokoli1 .

1. Did the video board work before the recap? If so, you should probably inspect your work very closely and check that there aren't errors. As you have two video boards, you may be able to compare one against the other.

If not, even though there's no picture, do you have high voltage? Can you feel static electricity on the face of the CRT? When the Lisa turns off, do you see a flash?


2. I don't really know for SunRem hard drives and can't really offer advice about them. Someone over on lisalist2.com might know more.


3. Do I understand correctly that the ProFile refuses to do the self-test whenever it connects to a Lisa that's off? If so, I've seen this happen before. Try starting the Lisa and see if the ProFile begins the self test. If it works, the Lisa may try to boot from the ProFile and fail because the ProFile is busy self-testing, but just wait --- once it's done, you can click STARTUP FROM and select the ProFile from the menu.
I checked the cable you bought. I don’t think that it is the correct one. I think you use a normal one and the Profile one is missing a pin… so that could be a problem. Do you need a picture how it should look?
 

mg.man

Well-known member
I bought this cable from Amazon:
Just looking at that cable again... I'd be highly surprised if all 25 pins are wired. I don't have a PC parallel (printer) cable pinout to hand, but I suspect some pins may be wired together or not connected at all. I recommend finding a fully wired 1:1 cable - or using a ribbon cable with DB25s either end.
 

Brokoli1

Member
Just looking at that cable again... I'd be highly surprised if all 25 pins are wired. I don't have a PC parallel (printer) cable pinout to hand, but I suspect some pins may be wired together or not connected at all. I recommend finding a fully wired 1:1 cable - or using a ribbon cable with DB25s either end.

I ordered a new cable and now the ProFile works and I was also able to install LisaOS 3.1 cleanly. The ProFile was running for over 1 hr and there were no problems.

Now I just need to fix my video board....
 

Brokoli1

Member
Hi @Brokoli1 .

1. Did the video board work before the recap? If so, you should probably inspect your work very closely and check that there aren't errors. As you have two video boards, you may be able to compare one against the other.

If not, even though there's no picture, do you have high voltage? Can you feel static electricity on the face of the CRT? When the Lisa turns off, do you see a flash?


2. I don't really know for SunRem hard drives and can't really offer advice about them. Someone over on lisalist2.com might know more.


3. Do I understand correctly that the ProFile refuses to do the self-test whenever it connects to a Lisa that's off? If so, I've seen this happen before. Try starting the Lisa and see if the ProFile begins the self test. If it works, the Lisa may try to boot from the ProFile and fail because the ProFile is busy self-testing, but just wait --- once it's done, you can click STARTUP FROM and select the ProFile from the menu.

Bad news...i replaced the BU406 but the videoboard is still "dead". I don't see any flash at startup or anything with high voltage....

Do you know which parts like to be broken or which are responsible for the high voltage? Maybe someone has a spare part for sale or can fix my board for money? Im from Germany by the way...
 

stepleton

Well-known member
i replaced the BU406 but the videoboard is still "dead"

Sorry to hear this.

Does the new BU406 measure the same as the BU406 you replaced? If it does, there's still a suspicious difference that might be worth tracking down.

Quick question: are both your boards the same revision?

What test equipment do you have?

-----

I'd now recommend having a nice, thorough probe around the board. (It sounds like you've done this to some degree?) It would be nice to be more certain that this is a component failure; even nicer to get lucky and find the problem.

Using your multimeter in diode test mode: test diodes. Compare with your other board. Test transistors too in diode test mode. (It sounds like you tested in resistance mode?)

Check shorts across capacitors. Check whether any of the trimpots at top are dead short or full open. Check connectors; make sure they look all right.

You've already inspected the solder joints (really thoroughly, under a very bright light I hope); get a good look at the components too and see if anything looks distressed or cracked.

Check the card-edge connector: does it look tarnished or damaged?
 

Brokoli1

Member
Sorry to hear this.

Does the new BU406 measure the same as the BU406 you replaced? If it does, there's still a suspicious difference that might be worth tracking down.

Quick question: are both your boards the same revision?

What test equipment do you have?

-----

I'd now recommend having a nice, thorough probe around the board. (It sounds like you've done this to some degree?) It would be nice to be more certain that this is a component failure; even nicer to get lucky and find the problem.

Using your multimeter in diode test mode: test diodes. Compare with your other board. Test transistors too in diode test mode. (It sounds like you tested in resistance mode?)

Check shorts across capacitors. Check whether any of the trimpots at top are dead short or full open. Check connectors; make sure they look all right.

You've already inspected the solder joints (really thoroughly, under a very bright light I hope); get a good look at the components too and see if anything looks distressed or cracked.

Check the card-edge connector: does it look tarnished or damaged?

Thanks for the tips. I will check everything in the next few days and give feedback
 

Berenod

Well-known member
Just FYI, I too have Lisa (2/10) with nothing on the CRT. Pretty much same as yours, no high voltage.
Boot goes as expected from the beeps, the "no keyboard/mouse" beeps, followed by the "no data from the drive" beeps which is to be expected from the widget drive.
I managed to source a videoboard from the USA, but it is taking it's sweet time getting over here (am in Belgium by te way).

Once I have it I can test to see that that one works (hopefully!), then start comparing and see where the current one goes wrong.

By the way, in case you haven't found it yet, full schematics of the videoboard (and pretty much anything else in your Lisa) can be found here:

 

Brokoli1

Member
Sorry to hear this.

Does the new BU406 measure the same as the BU406 you replaced? If it does, there's still a suspicious difference that might be worth tracking down.

Quick question: are both your boards the same revision?

What test equipment do you have?

-----

I'd now recommend having a nice, thorough probe around the board. (It sounds like you've done this to some degree?) It would be nice to be more certain that this is a component failure; even nicer to get lucky and find the problem.

Using your multimeter in diode test mode: test diodes. Compare with your other board. Test transistors too in diode test mode. (It sounds like you tested in resistance mode?)

Check shorts across capacitors. Check whether any of the trimpots at top are dead short or full open. Check connectors; make sure they look all right.

You've already inspected the solder joints (really thoroughly, under a very bright light I hope); get a good look at the components too and see if anything looks distressed or cracked.

Check the card-edge connector: does it look tarnished or damaged?

Today I measured the transistors with my new multimeter and compared them with the working board.

The U1 voltage regulator had completely different values on my board. 1.28V vs. 0.73V and 0.9V vs. 1.82V. So I think it is defective. Strangely enough, I was able to measure a clean 28V at point R39 when installed and also set this value with the "Width" pot.

Is this the correct transistor for U1 on eBay?
 

stepleton

Well-known member
Looks like the right kind of thing, but U1 isn't a transistor --- it's a voltage regulator, an integrated circuit. It might not surprise me too much if U1 differed between devices, particularly if they might have been made by different manufacturers, who have designed the underying silicon differently. See e.g. http://www.righto.com/2014/09/reverse-engineering-counterfeit-7805.html for an exploration of manufacturing differences for the 7805 +5V regulator.

In this case, also, the measurement seems likely to me to be affected by the width potentiometer R2. Are you sure that R2 on both of your boards was adjusted to exactly the same value?

If U1 was emitting +28V, it seems to me like it was probably working. If you want to buy a new one, though, I would avoid eBay and try a modern part first --- it may be cheaper. Farnell is happy to sell me a part in the UK for 50p.

Any information about some of the other things I asked about?

Does the new BU406 measure the same as the BU406 you replaced?

Are both of your video boards the same revision? Which revision are they?
 

Brokoli1

Member
Looks like the right kind of thing, but U1 isn't a transistor --- it's a voltage regulator, an integrated circuit. It might not surprise me too much if U1 differed between devices, particularly if they might have been made by different manufacturers, who have designed the underying silicon differently. See e.g. http://www.righto.com/2014/09/reverse-engineering-counterfeit-7805.html for an exploration of manufacturing differences for the 7805 +5V regulator.

In this case, also, the measurement seems likely to me to be affected by the width potentiometer R2. Are you sure that R2 on both of your boards was adjusted to exactly the same value?

If U1 was emitting +28V, it seems to me like it was probably working. If you want to buy a new one, though, I would avoid eBay and try a modern part first --- it may be cheaper. Farnell is happy to sell me a part in the UK for 50p.

Any information about some of the other things I asked about?

Does the new BU406 measure the same as the BU406 you replaced?

Are both of your video boards the same revision? Which revision are they?

I removed the U1 on both boards and then measured it, so the R2 could not have had any effect. I have ordered a new MC7824CT and then replace it.

The BU406 has pretty much the same values as the new one.
I have now measured all resistors, diodes and transistors and found that CR1 is defective (0V). On the other board I measure 0.73V. CR1 seems to be responsible for the 5V, if this is missing, this explains of course a lot. So i will order this 5,1V Zener from ebay, too.

To measure in the installed state is really difficult with the Lisa, I do not dare because of the high voltages.

Revision of my board is J, the working one is H.
 
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Berenod

Well-known member
To measure in the installed state is really difficult with the Lisa, I do not dare because of the high voltages.

Revision of my board is J, the working one is H.
My major worry as well once I get the parts and need to start working on mine!
 

stepleton

Well-known member
CR1 seems to be responsible for the 5V, if this is missing, this explains of course a lot.

This explains a whole lot if it's actually the case.

If you look at the bottom left of the schematic, you can see that the +5V supply is used to create a signal that inverts the horizontal drive signal (the horizontal sweep). If it's not there, then (following the trail through Q7, Q8, Q4, Q5), there's no oscillation going into the flyback, and that means that there's no high voltage (as well as no horizontal sweep).

Can you extract the CR1 that you believe to be defective and test it in a breadboard? It would be nice to confirm that it is actually broken. Find a resistor that's around 220 ohms (that's the value used on the video board) and hook it up with the diode in this arrangement. Supply, for example, 9V across U_in (positive to the top terminal, negative to the bottom) and measure across U_out. If you don't see +5.1V, then that zener was a goner. (The resistor may get hot, so don't leave this connected for too long.)

You may also want to use this setup to test your eBay order. I don't understand German, but is it really the case that the eBay seller wants you to pay two euros for a regular old zener diode? If so, this is pretty extreme. Just like it seemed you were paying ten times more than you needed to pay for a voltage regulator, here is the identical part for 13p, brand new from a major electronic component retailer. (You'll need to find a place to buy in Germany, I suppose, but the cost should still be very low.)

If you do find that CR1 is truly broken, I would actually try replacing it without replacing U1 and seeing if that fixes the video board. It's nice to know a specific cause.

To measure in the installed state is really difficult with the Lisa, I do not dare because of the high voltages.

Can't disagree with you here! Fortunately it may not be necessary to do that.
 

Brokoli1

Member
I have good news: The Lisa runs again like on the first day!

Actually broken was the capacitor C3 (10uF), which I had renewed, but that was a LowESR. Apparently it does not get along with the rest in the 5V rail. The voltage regulator U1 and the diode CR1 are ok.

Thanks for the great support! I will take some pictures of the Lisa soon and upload them here.
 

stepleton

Well-known member
Congratulations! I am surprised but will try to understand better how that mattered. How did you figure it out?
 
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