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I try to repair an Apple II Europlus and the only thing I get are some vertical bars at the screen. No beep and the keyboard doesn't respond. Where can I start with troubleshooting? Is it possible to start the Apple without a keyboard?
In theory (someone correct me if I'm wrong) no beep would indicate the 6502 isn't active. Not likely the chip is bad, pins could be corroded though. Careful not to break pins taking it out to check You could check the speaker to see if it's bad first. Did you pull all cards and try it?
One thing is bad ram ICs or bad logic ICs (the 74LS-something). Have you tested the chips in a testing device or in another working apple II?
The keyboard is not necessary for the Apple II to start.
In the meanwhile , the computer works but not reliable. Because the motherboard is mounted with spacers in the case, the board can bend a little bit. When I put a little force on the board the screen is filled with strange characters or the computer crashes. It seems there are one more bad connections in the board or the chip sockets. The connector of the power connector seems not the problem because the voltages on the board remains stable and the computer don't restart it selfs. How could I determine where this bad connection is?
Ps. The RAM chips are replaced by new ones and I have repaired the power supply but the problem is not disappeared.
Reseat all 74LS, ROM, and CPU.
Using Contact Cleaner in the sockets may help.
If that doesn't help, then it could be bad traces on the board or bad solder joints.
Finally I found the solution, the pins of 74LS174 at B5 are oxidized and also after cleaning the pins of the IC, the connection with the socket is not reliable. After replacing of the chip socket of the 74LS174 the Apple works without any problem again!
Feels great doesn't it?!
Yes, It was a great moment that it works stable and I have already 2 working Apple IIe's and I like this Europlus very much.
Do you know if it is possible to add a Z80 card and an 80 Column card to an Europlus?
Yes to both. The 80 column card I presume is a combined 64K / 80 column expansion card in the appropriate slot adjacent slot 3 in a Europlus.
The Z80 card usually goes into slot 4.
The combined 80col/64k card is for European //e where the AUX slot is in front of slot3 instead of beside slot 1 (in the area where slot 0 is on a ][+ or Europlus). Most 80 column cards that work in a ][+ generate NTSC video. They normally only have 2k of RAM for the text buffer not 64k like a //e. For a Europlus I'd think what you'd want for an 80 column card would be something that generated PAL or SECAM or whatever the video standard used in the particular country for composite video was. I don't know a lot about that. Europlus are super rare over here in the US. I've rarely ever seen one, only people who moved here from Europe or a few collectors have them really.
As for the Z80 card... slot 4 is indeed the normal standard place to put one. And its no different really US or Europe I don't think. Excepting possibly there might be language specific CP/M software I suppose. Again, not something that was common over here.