Hello everyone.
New to the forum and first post.
I recently got my hands on an Apple II europlus and a monitor iii, with disc drive
When i power it up I get a beep
But the entire screen is green with a flashing cursor.
I type in anything , hit enter get a beep
Cant see any characters - Just a green screen with a flashing cursor
the direction keys work
when i boot it up with the disc drive card installed it boots a game ( choplifter screen) but then freezes.
I think the machine is mostly working but have little to no experience with Apple II
I have some pictures but it says below to NOT upload images. Where do i upload images
Thank you for any advice
Update - Ive cleaned all the chip legs , one by one - removed chip , cleaned legs with a rubber, reseat chip - every one on the board , but no change.
no chips seem to be getting warm
board is fitted with all 6 roms
tried removing roms , leaving just F8 and FO - still the same.
i removed top 2 rows of ram chips - still no change - powers on , beep , screen is ramdom lines, grids for a spilt second, then video memory is filled. But its filling the screen with all green. with the cursor flashing away
I have 1 spare board that does not work at all
I swapped ROM SPCL (a5) with same from spare board and i now have a green screen with a series of dots. As if one pixel of a character is appearing But this has now caused a variation of the screen being all on - i can see very slight changes in pixels at the top of the screen - it is the area where the machine is displaying 'AppleII'
if this rom at A5 ROM SPCL is faulty might it cause a problem like this
Im reading all I can on the forum and trying all i find. Can someone tell me what chips are related to video and video memory
Have you checked the service manual? Chapter 10, "Motherboard Video Failure Symptoms" lists the chips which likely cause each described symptom - like the "screen all white (green)" issue:
https://apple2online.com/web_documents/Apple%20II%20Level%20II%20Service%20Manual%201981.pdf
Couldnt follow the link but found the manual - Perfect!!
Exactly what I need
Thank you Macfly
Update
FIXED!!!
Thanks for that link MacFly
the problem was the A5 Character ROM.
I reprogrammed it with a minipro tl886c6 with an image og the 341-0036
at first i got better resuts
I did it again and increased the VDD write voltage from 5 to 5.5 volts
Powered it up and my Apple II europlus is working 100%
Thanks again MacFly - That manual is a must have
Johnaton27 wrote:
Nice! Did you just reprogram the original PROM device or did you replace it and program a fresh (E)PROM?
Yes, the Apple engineers certainly did a great job when they wrote those service manuals. I wished today's service manuals would still be on the same level as they were in those days...
the original rom was the generic apple one
I swapped it with the eprom from the spare board - went from all white to grids of dots and the repeating pattern was disturbed at the top of the screen , telling me it is trying to display applle ][
downloaded the image and re flashed the eprom - got better results ( more dots) -
increased the vdd voltage by half a volt and reflashed it again
perfect picture
I am at it now all day .
nothing will load from the discs i have.
read about testing the ram with HGR and HGR2 command
found lots of junk on display for HGR2 - bad ram
stripped back to first bank - got a clear hgr2
kept going untill all 3 banks are now full with good hgr2 but i dont think hgr2 is is using 48K
i just managed to load dos ver3.3
trying to find some diagnostic program on the old floppys to test the memory but i cant find anything
opened and cleaned the head of the drive
is there a program i can type in to see what ram i have
i had an apple ii e years ago , but cant remember anything.
But al least I have a machine , good keyboard,
can you reflash a prom ?
i didnt even try
I thought you can only flash the eprom ( the one with the glass window)
Well, no, I'd be really surprised if you could. That's why I was aking, since your original description sounded like you reprogrammed an original chip. It now makes sense when you say the chip was an EPROM though.
The programming of a PROM should be irreversible, since the bits are stored by blowing fuses. Well, you could probably blow further fuses, but otherwise I had never heard of a PROM which lost its content, unless its completely broken (and then nothing helps). EPROMs are different, of course, since they are made to be reprogrammable.
Having a great time with it.
At first I tried to enter small program. Listing the prog resulted in crash. Bad ram
Swapping ram chips results in program listing and running.
It came with language card with lead going to top left ram chip.
But because some of my ram chips are dead I cant use it ( i assume i need 3 full banks to add the card)
I have 2 rows of ram and im not sure if they are all good.
When i list a program i see some pixels on some characters flasking on and off- i imagine it is bad ram -
i want to buy good ram chips
MacFly - can you reccomend replacement chips , what i should be looking for
You need 4116 DRAMs.
https://www.jameco.com/z/4116-15-Major-Brands-Dynamic-RAM-16kx1-150ns-DIP-16_41339.html
Man this all sounds so familiar! :-)
I had good luck with this AliExpress vendor: https://www.aliexpress.com/item/4000115812498.html
(in fact I just ordered another 20 to help me diagnose my Apple II europlus)
Good luck! I found the best way to test individual memory chips was to stick them in the first few slots of the first row. That way if they were going to fail, they'd fail on first boot.
(Mine is being very tempramental. Just got my language card working and now the main memory is being twitchy again.)
John