Trouble booting

It would be usefull to add pictures from top and bottom side of the mainboard.

view thread :
http://www.applefritter.com/?q=content/apple-ii-dont-store-apple-garage
for example...

Hello jpxl8ed,

the red coated wire from keyboardsocket to 74LS257 is defenitly wrong and hazerdous.

The row of RAM-chips from position D3 to D10 ( dark chips ) seem to be in extreme
bad conditon ( oxydated pins ). I would not trust a single chip out of that bunch.

Instead i would strictly recommend to remove that chips and swap the RAMchips from
row E3 to E10 instead in that row D for testing the bootup behaviour.

But for that purpose you also would have to relocate the on 4116 chip beside the plug of the
languagecard back to the mainboard and complete the row of RAMchips in row E.

The picture of the topside of the mainboard is rather bad with bad focus ( missing sharpness )
so that i can't zoom in and / or read chip labels.
Could you please take a second better picture ?
It seems that this mainboard has been resoldered by some guy and he wasted a lot of solderlead....

speedyG

First thing when I get a new classic computer that's acting up is to go over the ICs, reseat them, clean their pins. Use a mild abrasive like an eraser and then apply some Deoxit.

Whenever I read the word, "Deoxit" I go insane.

Whenever I read the word, "Deoxit" I go insane.

How so? It's a benchmark. A gold standard in contact maintenance.

Whenever I read the word, "Deoxit" I go insane.

How so? It's a benchmark. A gold standard in contact maintenance.

We are still back at posting #3, last section....
the last picture ist perfect in lighting and scale but it does not display the entire board...
by that i can't inspect the entire mainboard for possible trouble...

besides i recommend to check the following pages:

http://www.appleii-box.de/D04_resurection.htm

and

http://www.appleii-box.de/H198HomeRepairGuide.htm

speedyG

Whenever I read the word, "Deoxit" I go insane.

How so? It's a benchmark. A gold standard in contact maintenance.

I'll do my Levar Burton impression and then quote a member here...

But you don't have to take MY word for it.

De oxy will work... but it uses chemicals that remain at the surface and after cleanup
that area will very soon start again with oxydation - faster than normal.....
that´s the reason i never use it anymore....

Whenever I read the word, "Deoxit" I go insane.

How so? It's a benchmark. A gold standard in contact maintenance.

I'll do my Levar Burton impression and then quote a member here...

But you don't have to take MY word for it.

De oxy will work... but it uses chemicals that remain at the surface and after cleanup
that area will very soon start again with oxydation - faster than normal.....
that´s the reason i never use it anymore....

That's why you want to use PreservIt after cleaning it.

I've uploaded the picture back with some comments and markings.

A: ( yellow enlighted ) The first row and third row of RAM should be extracted -
at least till the tests with the computer are solved that far that the
computer boots correct ending at the regular prompt.

B: ( orange enlighted ) Use while performing the tests this row of RAM chips
and move them for the period of testing into the front row at position C3 to C10.
Test first time bootup before proceding to point C:.

C: ( blue enlighted ) If computer does not boot correct next step will be to
swap the 2 74LS08 chips in position and then check again for bootup.

D: ( violett enlighted ) If test B: and Test C: fail next step will be a kind
of "swap around game"..... The 4 violett merked chips are 74LS02 chips.

Each time you shall move/swap around the 4 chips 1 step counter clockwise.

Then try bootup.

If the bootup screen changes please take a picture from screen.

This helps to narrow down the problem.
If the test fails again perform next counter wise "swap around game" and try bootup again.
If all 4 changes do not change the display at bootup then post here for next procedure steps.

speedyG

Whenever I read the word, "Deoxit" I go insane.

How so? It's a benchmark. A gold standard in contact maintenance.

I'll do my Levar Burton impression and then quote a member here...

But you don't have to take MY word for it.

De oxy will work... but it uses chemicals that remain at the surface and after cleanup
that area will very soon start again with oxydation - faster than normal.....
that´s the reason i never use it anymore....

That's why you want to use PreservIt after cleaning it.

Not easy for the products of today which contain plastic.

That's one reason why I stay away from these kinds of products.

PreservITfi, P5S-6, 5% Spray, 142 g contains Stoddard Solvent CAS # 64742-88-7

Reference the MSDS: http://store.caig.com/core/media/media.nl?id=910&c=ACCT113328&h=ed5c576aa4bad5eb829a&whence=

Reference this quote about this substance:

"Stoddard Solvent attacks plastic rubber and coatings.

Reference this pdf file, page 3:

http://nj.gov/health/eoh/rtkweb/documents/fs/1736.pdf

I have tried many contact cleaners throughout the years and before the advent of environmental laws banning the use of CFC's, these products worked well.

After the laws were passed, the new stuff works terribly.

If I have a pot that I want to clean, I use a four step process.

1). I use a special chemical cleaner to remove all of the oxidation - this cleaner is something intended for another purpose but it works on any metal and it works 100%.

2). I use WD-40 to remove the first chemical.

3). I use alcohol to remove the WD-40.

4). I use axel grease to lubricate the pot and when I do so I make sure it does not touch the plastic - this process prevents oxidation permanently.

I sometimes substitute the axel grease with a mix of two different grease products.

I have done this for 25+ years and have not had a problem.

It is a permanent solution.

No need for spraying of contact cleaner again and again.

No need to worry about future oxidation.

Hello jpxl8ed,

let's think public about analytic thoghts about this device.....
and let's use the "IC-arbitrary Chart" on top of this page:

http://www.appleii-box.de/D04_resurection.htm

The picture of your bootup screen in the initial posting...
the unit displays at least 2 characters in correct manner without missing pixels...
this means that the unit has at least the correct access to this 2 specific chars in the
character ROM and forwards them correct to the RAM and outputs them correct at the display....

In the Char ROM that chars are stored as "pixel matrix" and then the unit picks
them from the ROM pixelline by pixelline and shifts them into the video RAM.

At the other Hand some other expected characters are not displayed at the screen
and it's at the moment not clear if the content of the Char ROM is empty there or
if the access to the ROM causes it to pass over a "invisible character" that simply won't display
like a Ctrl+N or any alternating "invisible Character".

At the other hand this "stage of booting" and the related crash happens rather late -
at a point where the bootup process is nearly completed.....

The related parts are for character display:
2513 Char ROM at position A5
Shift 74166 at position A3
and the 2 keyboard buffers 74LS257 at position B6 and B7.

At this point we may assume the regular RAM in the row C from
position C3 to C10 is working correct.... otherwise you would view
either empty white squares or bars of so called "early bootup crash" like displayed in lower part of that page.

And if adressinglines are affected by the mistake it will be rather more
at the regular Applesoft ROMs the higher adressing lines...
and we also may assume the datalines of the regular use in the
computer also to be O.K. - otherwise the display would show up with
some kind of "pixel mistakes" in the display of the characters at the screen...

We may also conclude that the Video clocking is O.K. as well as the
Byte-Dot conversion and the normal process of Char-Video conversion.
Similar is valid to the RAM-Video Conversion.

This gets the following chips off from the list of suspects:
74LS194 at position B4 and B9.
74LS257 at position A8
74LS151 at position A9
74LS194 at position A10

So the list of our suspects remains at the one hand at the Char ROM section listed above
and at the other hand within the section of the logic chips at position A11 or higher
or at position B10 or higher....

By the performed "swapping game" and tests and the fact that no change happened at the
screen while testing the "swapping game" we may with restrictions also take off the
4 x 74LS02 chips at position A12, AB14, B13 and B14 from the suspects list.

And the initial swap of the 74LS08 between position H1 and B11 also did not result
to change in behaviour so they may also be taken off from the list of suspects.

I'm not sure about the given pictures but it seems to me that at least at one of the last ones
the 74LS32 at position C14 is not really completly firm in its socket. I'd recommend to check that.

Some of the higher adressingline jobs are performed by 74LS138 and 74LS139 chips.....
so that's one trace of tests that should be now performed....

and the of the so called "control line logic" is also remaining at the moment without
verification....

So before ordering chips there are still some "swapping games" that might be remaining at the moment to
narrow down the problem.
For better understanding:
If a damaged chip is moved from one location to another location the fault won't be anymore the same
like viewed before.... if location changes - then also the mistake will change and affect the bootup
with a change in the bootup screen....

Unfortunately some chips are unique on the board and can't be swapped in postion for
testing purpose.... but a bunch of them can be tested by such swapping...

I'll try to order them by the experience that i've made with the amount of occasions
the that chips might fail... most suspicious ones first and least suspicious ones last...

if a swap happens that causes a change in the bootup screen - then one of the chips
you have swapped last verifies to be damaged !

Within the picture i enlighted again those chips of same kind in same color.

light yellow => 74LS74
light green => 74LS257
light orange => 74LS194
light blue => 74LS153
and finally the busadressingchips themselves:
light violett => 8T97
and
light purple => 74LS138

Remember: perform only one chipswap at a time and powerup hunting for change in behaviour !
If you swap too many chips at one time you don't know which chip caused change in behaviour.

If no swap at all causes a change in behaviour it gets time to order and replace that chips
that could not be tested ( unless you have another source for swapping ):
74LS04
74LS11,
74LS20,
74LS32,
74LS51,
74LS139,
74LS151
and
74LS166.

When you decide to order and replace bear in mind that most of these chips
are "common TTL logic chips" that can be ordered at price about half a dollar up to one dollar per chip.....
but some few are obsolete and difficult to find ( i.e. 8T97 )

Not to forget: there is still a chance of a damaged ROM ( F0 or F8 )...

just for completeness some download recomendations:
http://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Books/Sams%20ComputerFacts%20-%20Apple%20II%2C%20II%20Plus.pdf

http://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Books/W.%20Gayler%20-%20The%20Apple%20II%20Circuit%20Description.pdf

http://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Books/Chilton%20-%20How%20To%20repair%20and%20maintain%20your%20Apple%20Computer.pdf

http://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Books/Jim%20Sather%20-%20Understanding%20the%20Apple%20II.pdf

sincerely

speedyG

Well that's at least that far good news that seemingly 1 problem is located....
74LS138 a standard TTL Chip and in general if you don't order them from China
there is a rather good chance that even ebay may deliver the correct chips...

but in general i would prefer a reliable local shop in same country ...
If you are located in USA Jameco would be a reliable source:
http://www.jameco.com/z/74LS138-Major-Brands-3-TO-8-DECODER-DEMULTIPLEXER-DIP-16_46607.html