I want to strangle this //e

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I want to strangle this //e

It has been almost six years since my registration on this forum, but I don't think anyone would care. What comes to the table is my nice flea market find; a revision B //e, with what appears to be some printer card, an unknown peripheral card and a Disk ][ interface. So let's cut to the chase.... doesn't work.

All I got when I did a bench test was a bunch of striped blocks, and when I wiggled around the PCB, lines started to spaz and show up out of nowhere. I could type in a bunch of keyboard keys and find that key inputs did work, and each press caused the screen to spaz out more. So it was barely alive, but one thing I could notice was that even with the proper speaker the machine made no beeps, meaning that the speaker isn't receiving the correct voltage or that the machine isn't actually getting far. Tried transplanting a speaker from my previous //e, with no results.

So I tried removing the RAM chips. Instead of question marks... more garbage, except that the screen was completely spastic and entire gibberish. It was like this for an hour until I turned it off. Replaced the 6502 did nothing to help, and swapping out the HAL did not help either.

So I tried cleaning the motherboard with all chips completely removed. Nothing. On the way, I also broke the CAS line to a certain DRAM chip by breaking resistor R73 and somehow accidentally messing up it's solder pads to the point where I can't use them any more. Which means that I will have to patch up a nice little wire before I can use all the RAM again.

At this point, I might just get it sent out for repair, but I'll post photos for anyone who wants to take a look later.

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Should have posted that in

Should have posted that in "Hardware Repair Help" by the way...

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Hi. Sorry for your troubles.

Hi. Sorry for your troubles. Do you have another IIe to swap your unknown parts into to determine if any parts from the "bad" one are good parts?

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http://www.appleii-box.de
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OK, with no functioning RAM

OK, with no functioning RAM chips, the system either boots to something like this: https://imgur.com/a/UuY6pkg, or, something like this: https://imgur.com/a/hUlGaJc

A video of the latter symptom: https://imgur.com/a/hUWjFMW

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Did you try to measure

Did you try to measure Voltages from powersupply ? Results?

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The power supply is from a

The power supply is from a completely working //e. So it can't be the problem.

I think that one of the problems is a conflict within the video ROM's bus. If I replace the video ROM with one from the same working unit, I still see complete garbage that does not look like anything in the video ROM whatsoever.. The IOU has been swapped from once again, the good machine, and nothing has changed there, so the problem is probably within...

More resistors and capacitors that are likely to be dead and thus causing the video ROM bus to go haywire. Quick, someone make me bleed faster...

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Hello

Hello

i neither want to waste your nor my time....

When i passed the link above, i expected you to read that page...

next posting should have been:
I have a enhanced IIe with mainboard of US version or something similar....

Also i would assume that you have checked the ROM-set to make sure
that the ROMs are not mixed up between enhanced or non enhanced ROMs and that
the languaghe version of the Char ROM fit with the version of the mainboard as well
and that the CPU matches the version ( enhanced or non enhanced )....

for serious diagnostic this is vital information If i ask to check voltages thats not just for fun and telling me that the
supply is OK in another system isn't the expected answer:
You are talking about a damaged mainboard and in such case voltage measurement is also
vital info because a "drifting" voltage might indicate a damaged chip !

50% to 80% of damages to enhanced versions of the IIe result from wrong storage
and killing of the CMOS CPU by static discharge !

Indicating to me that you did not read the page related to the link above
is your guess about the IOU ! That chip is nearly not at all involved in that kind of mistake !

If you make a guesss about a text with a "blank" IIe ( without any Interfacecard inserted )
the startup process is rather more dependent to the HAL and the MMU because the Mainboard needs
correct clockcycles and the MMU handeles the communication between basic 64KB of RAM, ROM access and CPU !

so are you asking for serious diagnostic or hunting for a "lucky shot" ?

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Hi, let me explain. The

Hi, let me explain. The enhanced board does not have any problems. The nonenhanced one does. I specifically stated that the problematic board was an original Revision B. The closest match to the symptoms you described that match my board is this: http://www.appleii-box.de/APPLE2/_resurection/Errorscreens/crash%202.jpg

The CPU is working fine. I tested it in another machine with a socket for a 6502. I have the original video ROM for this board. I just used the video ROM from an Enhanced //e for testing because despite that it has different graphics data, I know it is good and there are no dead lines or any other sign of damage. All voltages in the power supply are normal. All logic chips that I could test in my TL866A programmer test out OK.

But, I will say this: The power supply that originally came with the nonenhanced //e was dead. Completely dead out of the water; Astec variant. Firing it up with both boards that I have did nothing. No magic smoke though.

I'll have a go at putting the nonenhanced CD, EF and Video ROMs including the 6502 into the enhanced board to see if any ROMs are faulty. If nothing else, it is probably that the MMU in the nonenhanced board is bad after all; unfortunately, I have no substitute for the MMU.

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Changing the 3 ROMs ( CD, EF

Changing the 3 ROMs ( CD, EF, and Video ) together with the CPU should result the change from a IIe to a //e and result to a working enhanced model. The MMU in the enhanced and unenhanced are same. So you can make proof of the damage of the MMU. Like explained in my page there is no chance to purchase a MMUchip except steal from another mainboard.

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