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matsondawson
April 21st, 2010, 05:32 PM
Hi,

I've been looking for an Apple 2c repair guide on google but can't seem to track it down, so I'm asking you guys. I bought a 2c recently and when turned on it produces the screens as below, can someone tell me what they think is wrong?

I put read all the roms in a reader and they seem fine. I tried a different cpu, which made no difference. Re-seated all the socketed chips. Check there is clock and bus data (it looks like the cpu is working). It looks on the first screen like there is a cursor running through memory, maybe a ram test? I'm thinking DRAM or something in between? (This is the 2c board version that has 4, 64k x 4bit DRAMs)

Cheers,
Matt

http://imgur.com/25qWhl.jpg
http://imgur.com/Xvr1Pl.jpg

channelmaniac
April 21st, 2010, 05:37 PM
Bad RAM.

Can you turn it on without the keyboard plugged in and see what it does? If it can start up enough you can get a report back on which RAM is bad. Otherwise you'll have to shotgun the 2 lower chips... luckily it's not the version with 16 DRAM chips. ;)

matsondawson
April 21st, 2010, 05:50 PM
Same problem with no keyboard. I've removed the disk drive as well. The ram is shown as D41464-22, (off the top of my head), is it ok to use a higher speed DRAM? I know it would be ok with SRAM, but not sure on the DRAM front. I may solder 4 dip sockets in and try booting with 2 chips to see if I can get somewhere.

Thanks for the help.

matsondawson
April 21st, 2010, 05:51 PM
Also the keyboard reset appears to work, so if that is a software not hardware thing then it suggest the ROM code is running fine.

channelmaniac
April 21st, 2010, 05:53 PM
Yup... they are 200ns DRAM. Actually anything 300ns or faster will work. It's easy to come across 80, 100, 120, and 150ns 4464 chips.

RJ

Drken
April 22nd, 2010, 12:29 PM
I hope I'm not about to show some real ignorance here but...

I have the same problem when I tried my Apple IIc with an Apple monitor - got the same pattern you show in the first photo. When I tried another monitor on the IIc, both the monitor & the IIc worked just fine. So my suggestion is to try another monitor & see if the IIc is fine and its the monitor that is having the problems.

matsondawson
April 22nd, 2010, 12:34 PM
I hope I'm not about to show some real ignorance here but...

I have the same problem when I tried my Apple IIc with an Apple monitor - got the same pattern you show in the first photo. When I tried another monitor on the IIc, both the monitor & the IIc worked just fine. So my suggestion is to try another monitor & see if the IIc is fine and its the monitor that is having the problems.

I tired a 2c LCD with it too and it has the same output.

barythrin
April 22nd, 2010, 02:16 PM
Does the screen change when you type on it or give it a basic command for screen mode changes? My guess is bad ram also but that may also help you know that the video is displaying changes but the contents of the video to display are corrupt.

matsondawson
April 22nd, 2010, 06:22 PM
Does the screen change when you type on it or give it a basic command for screen mode changes? My guess is bad ram also but that may also help you know that the video is displaying changes but the contents of the video to display are corrupt.

No, typing has no affect, only control - reset changes the screen.

jwbavalon
April 23rd, 2010, 12:24 PM
Hi, have you tried the IIc diagnostics? With power on Control+Open Apple+Closed Apple+Reset then release the reset first and it gives a screen like you show only smaller. Once it runs through the MMU, IOU, ROM and RAM if all is OK returns "System OK". If not it stops and displays an error message, that is of course assumes that the ROM isn't corrupt and it doesn't run at all. On the Apple web site there is a description of the IIe component diagnostics which is similar to the IIc. It may help.

How long have you had the IIc LCD display? I've been looking for one for a couple of years .

Good luck.

dorkbert
April 23rd, 2010, 01:49 PM
Earlier IIc's do not have built in diagnostics.

Wikipedia (http://en.wikipedia.org/wiki/Apple_IIc) has a run down of varies revisions to the IIc's over the years. I was incorrect in stating that version could be identify by part number under the unit. In actuality it requires that you pop the unit and look at the part number on the ROM chip, or have the unit running and perform some peek(), which you can't since the unit is dead at the moment.

matsondawson
April 23rd, 2010, 02:35 PM
Earlier IIc's do not have built in diagnostics. You can find out looking at Apple P/N under the unit (this does assume that the inners of the unit hasn't been swapped out at some point in the past.)

I can't find a P/N on the bottom, but the model number is A2S4000. When I use the key combination the screen starts off as the 2nd picture looks, and when I release reset it goes back to as the first picture looks. Also the speaker clicks a lot.

matsondawson
April 23rd, 2010, 02:37 PM
Hi, have you tried the IIc diagnostics? With power on Control+Open Apple+Closed Apple+Reset then release the reset first and it gives a screen like you show only smaller. Once it runs through the MMU, IOU, ROM and RAM if all is OK returns "System OK". If not it stops and displays an error message, that is of course assumes that the ROM isn't corrupt and it doesn't run at all. On the Apple web site there is a description of the IIe component diagnostics which is similar to the IIc. It may help.

How long have you had the IIc LCD display? I've been looking for one for a couple of years .

Good luck.

I just got the screen, I paid a packet for it... untested... and when I got it the screen is all black, I assume the LCD fluid has leaked. If I look at it at an angle though I can barely see the characters come up.
So if anyone has damaged driver electronics, and wants to sell their LCD I'd be interested :)

channelmaniac
April 23rd, 2010, 03:18 PM
Bad RAM.

Can you turn it on without the keyboard plugged in and see what it does?


Hi, have you tried the IIc diagnostics? With power on Control+Open Apple+Closed Apple+Reset then release the reset first and it gives a screen like you show only smaller.

Powering up a IIc or IIe without the keyboard connected does the same thing, except that the diagnostics will run repeatedly if no error is found. It's a good way to burn test a system. ;)

RJ

matsondawson
April 23rd, 2010, 07:12 PM
Ok, all ram chips have been tested and work in a C64c.
The GLU chip appears to be hot, could that cause these symptoms?
Is there a 2c schematic around somewhere I can look at?

MikeS
April 23rd, 2010, 07:17 PM
I just got the screen, I paid a packet for it... untested... and when I got it the screen is all black, I assume the LCD fluid has leaked. If I look at it at an angle though I can barely see the characters come up.
So if anyone has damaged driver electronics, and wants to sell their LCD I'd be interested :)Sounds like maybe the backlight's not working; check for a loose cable, bad caps, or loose or cold-soldered SMT caps or resistors.

There's a how-to out there somewhere by a guy who put an LCD with a bad backlight into an old monitor case with a light bulb behind it; kinda cool...

matsondawson
April 23rd, 2010, 07:29 PM
Wait!?... it has a backlight? I thought it was transreflective. It smelt bad when i pulled it apart (gets on your fingers), and it looks like right at the corners it has the normal reflective backing, I can even see bit of a character in one of the corners where it hasn't gone black.

Just checked wikipedia and it says no backlight.

matsondawson
April 26th, 2010, 08:10 PM
Ok, all ram chips have been tested and work in a C64c.
The GLU chip appears to be hot, could that cause these symptoms?
Is there a 2c schematic around somewhere I can look at?

Bump! any ideas what ic's you'd check next. There's a latch there I'm wondering if it could be part of the problem?

channelmaniac
April 26th, 2010, 09:19 PM
CPU, GLU, MMU, IOU, IWM, and the filter on the drive side of the IWM can all cause the computer to go wonky.

MikeS
April 26th, 2010, 10:19 PM
Wait!?... it has a backlight? I thought it was transreflective. It smelt bad when i pulled it apart (gets on your fingers), and it looks like right at the corners it has the normal reflective backing, I can even see bit of a character in one of the corners where it hasn't gone black.

Just checked wikipedia and it says no backlight.Oops - sorry, crawling back under my rock ;-)

matsondawson
June 10th, 2010, 02:18 AM
Ok, I've figured out the issue. I picked up another 2c off trade me for $40 and swapped a bunch of chips. It turns out to be the CPU.
I did try another CPU, must have been broken too.

Gibsaw
February 3rd, 2014, 08:37 PM
Just a bump to this along a similar line... I have a IIc that's working mostly (won't load disks and shows a few bad characters)

It's definitely behaving like faulty RAM. I held down both apples and reset..Mine's been doing various RAM patterns in the HGR screen for some time. It seems to be orderly like it's still going, but it's sure taking a while.

My actual question is... Does anyone know how long the self diagnostic should take to run on an original rev IIc?

RWallmow
February 4th, 2014, 04:47 AM
Just a bump to this along a similar line... I have a IIc that's working mostly (won't load disks and shows a few bad characters)

It's definitely behaving like faulty RAM. I held down both apples and reset..Mine's been doing various RAM patterns in the HGR screen for some time. It seems to be orderly like it's still going, but it's sure taking a while.

My actual question is... Does anyone know how long the self diagnostic should take to run on an original rev IIc?
Usually takes about 60 seconds or so to complete, but like others have said with keyboard disconnected it runs in a constant loop.

For what its worth, I had a //e that PASSED its self test with BAD ram, so it's not a sure fire diagnostic test.

Toysoft
October 18th, 2014, 10:38 AM
Have got a problem yesterday on my //gs, here is the screen when I turn it on, the front led is green (ON), but there is no sound (beep when turning it on).

Any idea what could be wrong ? T21041hanks !

TS

RWallmow
October 21st, 2014, 06:23 AM
Have got a problem yesterday on my //gs, here is the screen when I turn it on, the front led is green (ON), but there is no sound (beep when turning it on).

Any idea what could be wrong ? T21041hanks !

TS

The IIgs is a VERY different beast from any of the earlier Apple II's, I would post a new topic, but off hand I would say check the RAM.