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Hi stepleton and others. Something really strange happend when I was working with the oscilloscope and the static RAMs. Suddenly the monitor is showing this. CPU error 41. I put in the I/O board , mouse and KB. Its working The text in swedish at the top is burned in on the screen when I...

Hi, I managed to get the logic analyzer working. Measured to all incoming pins of the MC68000. As I understand after reading the spec of the CPU. Its easy to attach test hook clips on the CPU. I had to solder thin wire on U2E to get proper signal. The analyzer save files in .sae format. her is...

Thank You stepleton for studying this ROM code. I double checked the CPU pins of earlier measurements and it was OK. Here is a picture of pins 1, 2, 3, and 4 of U2E, same signal of pins 234 and pin 7 of the expansion connector. Zero level slightly different for clarification. A neg puls of 25...

Some testing of the CPU board, without I/O board, no KB, no mouse, no floppy or HD. Pictures from ROM 341-0175-H Pin OE pin UA1 pin UA8 pin UD2 pin UD3 ROM 341-0176-H pin OE pin UA1 pin UA8 pin UD2 pin UD3 I have read in the Motorola M68000 user manual p 75...

Thank You mactjaap for that video. The videomonitor I use is an old Samsung LCD with a analog connection. Is working with the Apple II Europlus and my Apple IIc. see picture Its not working with Lisa. But if I connect the IIc monitor to Lisa I get this picture and video Rather strange but I...

Hi, its amazing how much knowledge is accumulated in this forum. Thank You all. In fact I tried yesterday to take out the I/O board and start it. RAM boards , KB, mouse and floppy drive connected. As lisa2 said its starting direct. Power lamp is on and the screen looks a little different. Most...

Thank You for suggestions how to proceed with this LISA 2. This is definitely above my level regarding retrocomputing and programming. I will take out the I/O board and do the tests next week and report.

Sorry stepleton. I apologize if I sounded rude. That was not my intention. I really appreciate your help and efforts to help me with this problem. I have read in Larry Pinas : Macintosh , Repare and Upgrade Secrets...

OK, that explains all the words without any specific help. The CPU clock signal is present at pin 8 at the expansion board socket Below is two videos of when I press the reset button three times. LISA is powered on for one min and then reset is pressed. First is when all bords are mounted...

Thank You both for Your comments. I have already cleaned all connectors, inspected the boards etc and didnt find anything wrong. The only thing that happended between when it worked and didnt was that I moved it from the garage to the table. I have tested without any memory board and in...

I have a LISA 2/10, (H/88) that has been working good. The harddrive is dead but it has worked with the floppy drive and booting from that. Recently its not working. When I put it on the screen is white but no click, no sound , no error sound. Just a white screen. The lamp in the on button is...

The Q9 was OK but I noticed a bad trace to the Q9. After reparing that the AIII is booting ( Apple III system utilities) and the keyboard is working, but there is a videoproblem. No text, only vertical lines.  I have replaced the RAM on the 5V memory board but the same results. According to...

The Apple III is alive - partially The reason for it to wake up was a little suprise for me. I measured the 5V line at the motherboard when using the ATX PSU, it was 2.9 V but when I measured it at the cable at the PSU it was 5.0 V.  The reason for the voltage drop was that I used thin, bad and...

I tested the motherboard (connected with memoryboard, keyboard and monitor) with different voltages from Velleman . Only 5 V line. The current is displayed on the PS. Resistance calculated from that. Output V       Measured Amps                 Calculated resistance 0.5                      ...

I tested with a Velleman  programmable DC Lab Power supply. When set to 5.0 V it drains 2.0 A. Nothing is really hot on the board, the only thing thats warmer is the SY6522 ic at B6 thats 36 degr C. Also tested with a working PSU from a Apple II.  All four voltages. Same results as the tests...

Thank You techknight for that suggestion. I have an adjustable bench power supply but it can only deliver two voltages. Maybe I can combine with several PSU and all " 0 Volt" line connected.  Is it dangerous not to feed the AIII with -5V or -12V?  Can I test the motherboard without the...

Yes, probably.  But its strange (at least for me) that the resistance between 0 and +5 on the AIII is 215ohm and that implies that there is not a constant short. Maybe a capacitor thats defect??  

I have an Apple III,  A3S1 no 57901  motherboard  820-0043-00E  5V memory board. When I got it the power supply was dead. I´m trying to restore it but I have tried with ATX PSU unit that delivers -12, -5, +5 and +12V. Put in a new keyboard lamp. When I turn it on there no sound, no video, no...

Hi nvdeynde and techknight. I got a defect Mac Plus (240V) that was dead. No power on the analog board so I started to check all components. It was exactly the same fault, R55 had no connection, completly open. It was 33k but I replaced it with a 20k resistor ( according to Larry Pina...

Hi bibilit. That’s a little confusing for me. For Mac II-series machines with ROM SIMM slots, check to make sure the W1 jumper is removed (if a ROM SIMM is installed) or installed (if the ROM SIMM slot is empty). http://www.ccadams.org/se/pickle-faq.html According to BMOW , Mac IIsi: Insert a...