Apple II graphic fault

hello mjnurmey,
there are several causes possible that result with bad interaction of RAM with CPU:
bad busdriverchip ( those chips in the same line like CPU ),
bad timing ( chips in the line from oscillator to lineadressing decoders ),
noise on powersources ( bad capacitors that don´t filter the noise away from the power ),
and of course bad RAM-chips themselves....
not to talk about bad interfacecard blocking the adressinglines....
my advice:
start first tests without any interfacecard and only one row of RAMchips.....
this should lead up to a prompt - if the chips are O.K. and the lower adresslines are O.K.

( otherwise there is a problem with eiter the datalines or with a RAMchip in the first line )
then expand by inserting second line of RAMchips.... it should end up again with a prompt.....
next step would be to add the third line of RAMchips ( don´t forget to move down the one from the language card
and make mark to remember orientation of that chip on the card !)
thereafter you may put back the one chip to the language card and add the language card.

then the next step would be to add the floppydisk contoller with one drive connected....
if somewhere in between the problem raises again, the problam can be located within the chips swapped in back...
sincerely
speedyG

Hello mjnurney,
indeed a bad power supply can not only cause that mistake - it can ruin - if the use is continued - more and more chips with continued usage ! If the PSU smells funny ( like burned chemical ) it must be repaired before any other test can proceed..... trace where the smell is coming from... normaly you can follow that smell even if the PSU is switched off and the smell willl bring you to a burned or at least damaged component that must be replaced....
thereafter the PSU shall be tested at the outputs for the correct voltages and connecting a old harddisk with the 0 Volt, + 5 Volt and + 12 Volt is obligatory because the correct voltages can only be measured reliable with a connected load.
The measured voltages should then remain within a tolerance of +/- 0,5 Volt .......
you should not continue with tests at the mainboard unless you have confirmed the PSU to act reliable within specifications - otherwise the damages at the mainboard might be expanded !

BE CAREFULL WHEN WORKING INSIDE THE PSU ! THERE IS DANGER OF LETHAL SHOCK WITH 220 Volt or 110 Volt !

the chip at the row of the keyboard connector is the Character ROM and at is sometimes replaced with a Eprom....
normal is a 2708 or 2716 compatible ROM or Eprom. If some adapter-like constrution is used - then this leeds usually to a switch and indicates a popular modification of the old days....
some users added a second characterset....
normally the Apple II has only ony character set onhly upper case and one country code....
in U.S. Models the modification was used to add a lowertcase set to the Apple II... and in european Models
also a modification was popular to enable switching between U.S. char set or european charset or if 2 switches were added the switching of US/European and Upper/Lower case....

the correct purpose of modification shows up after Boot if title displays Apple close-bracket open-bracket or
Apple ( U with points above ) and ( A with Points above ).... dependent to switch position....

If like you told - no interface card is inserted - a common mistake is to forget to put back one of the RAM-chips back to that socket, where the flatcableplug had been inserted that went up to the language card.....
make sure that in the third row of RAM-chips ( the row most close to the CPU ) and the socket ( most close to the PSU ) is not left empmty ! This causes also the Apple to crash at Boot.... pay attention to the orientation of the notch of that chip !
sincerely
speedyG

The likely culprits are the electrolytics.
While other capacitors can go bad, generally most will remain fine.
Also be sure and check/touch up the soldering on the trace side.
It wouldn't hurt to check the diodes either.
If one shorted or opened, it would take out the electrolytics that much quicker.

opened up the PSU this afternoon and the following look very ill

Astec power supply AA 11040c
230vac 50mhz 0.5a

C23 capacitor 0,01uf X
C1 capacitor 0,1uf x

capacitors here look very old too and i'll change them..

c11 0,22uf +-10%
c17 0,022uf M
c10 0,22uf +-10%

C23 has exploded in half and smells like a burnt fire type smell

can anyone guide me on the voltage of these ? i haven't taken the pcb out yet to see if its on the 230v line.

Hello mjnurney,

first the data in your inquiry, then a summary...
C1 = 250 Volt ( min. 250 Volt )
C10 = 0,01µ 1000 Volt Ceramic ( min. 400 Volt )
C11 = 100 Volt( min. 60 Volt )
C17 = 100 Volt ( min. 60 Volt )
C23 = 47µF 250 Volt electrolytic radial
There is a bridge-reticifier at DB1 ( entry of the 230 Volt line that must be able to handle at least 250 Volt ( better 400 Volt ) and at least 1 Ampere ( better 1,5 Ampere ).

The damages indicate that a shortcut has occured ( probably a lightning stroke close to the house )
and that the wall plug had no safty circuit protection against overload.... ( old house and old slow fuses )
a lightningstroke is that fast that sometimes even the internal fuse is left intact due to the fact that its too slow....

the residy oily dirt outside of the exploded capacitor is bor-acid.... this must be cleaned carefully away
- it etches copperlayers away.

In such cases the bridgereticifer MUST be replaced too as well as also the Foilcapacitor
parallel to the powerinputplug
0,47 µ 275 Volt ( carefull this one can only be replaced with EXACTLY the SAME one ! )
and this one is really difficult to get.....

If Powersupply is O.K. and starts working again you must examine very carefull the mainboard too for shortcuts !
In regelar cases a part of the lightningstroke enters the mainboard and damages at least one buslinetranciever
and one RAMchip !

I have tried several times to repair such a damage and these Powersupplies failed very short later again...
My advice is to better immediatly try to replace the powersupply as entire unit.....

This might be a point to think about something like the description in my website:
http://www.harrowalsh.de/Elektronik/APPLEBOX/powersupply_upgrading.htm

by the way up to the time where the PSU is replaced you might use instead a old powersupply from an IBM Computer with some 150 Watt or so..... You just need to solder an adapter cable....
if the IBM Powersupply is ATX typ you must bridge 2 lines for the supply to start ... the instruction for that is availiable in the internet or in the mentioned page above....
sincerely
speedyG

With all due respect (and 37 years of experience as a component-level tech), it's much more likely that the electrolytics blew from age than a local lightning strike.
Switching power supplies place a heavy burden on their main filter caps.
High temperatures, high altitude and age can degrade these "wet" caps even more quickly.
I've repaired hundreds of power supplies and several Apple II supplies and in most cases it was only the caps and/or diode(s).
It's true that anything can fail, but it's still more likely to suspect aged components themselves instead of lightning.
Please note also that some diodes can be fast-recovery or zeners and should be replaced with exactly the same part type.

Hello Neon Forests,
i´d agree with most of the post - except one fact ( with respect ) - the one cap ( C23 ) exploded completly in the middle ( see explanation of mjnurney above ) and burned off..... i´ve seen this kind of damage 4 or 5 times in the past 35 years ( and once 30 years ago ) in one of my own computers , that occured during a thunderstorm and before i installed a ignition overload protection in my home powerlines.....
capacitors that die from age normally just start leaking the bor-acid - but they normally don´t blast just right in the middle....
sincerely speedyG

hello all,

I have removed one bank of lower ram *(near keyboard) and powered on - and i get a white screen ?

i have taken a HD pic of the ram in it original location so i can put them back exactly as they came out and placed them in line next to the Apple anyway.

CAP C23 is a metal oxide paper cap (X) it won't leak , it would just blow i would of thought?

i don't have a language card, just a disk controller card.

mike.

Hello Mike,

congragulations to the working PowerUnit.....

the instruction was clear......
( citation of first posting:
start first tests without any interfacecard and only one row of RAMchips.....
this should lead up to a prompt - if the chips are O.K. and the lower adresslines are O.K.
( otherwise there is a problem with eiter the datalines or with a RAMchip in the first line )
then expand by inserting second line of RAMchips.... it should end up again with a prompt.....
next step would be to add the third line of RAMchips ( don´t forget to move down the one from the language card
and make mark to remember orientation of that chip on the card !)
thereafter you may put back the one chip to the language card and add the language card.)

so the third line is the one closest to the CPU.......

the removal of rows of RAM MUST be executed from CPU towards to the keyboard !
The RAM closest to the keyboard are the FIRST 16kB of RAM ! This row is not reducable !
The Apple can´t relocate RAM like a PC, where you can just chose which bank you like to populate , it has fixed adessing by layer of the board !
0 kb RAM to 16 kb RAM is row closest to keyboard. It must stay populated.
16 kB to 32 kb RAM is the middle row.
32 kb RAM to 48 kb RAM is the row closest to the CPU.( the one with the chip moved up to the language card )
so if you reduce RAM removing the last row close to the CPU leaves the Computer with 32 kb of RAM !
if you remove the both rows towards the CPU leaves the Computer with 16 kb of RAM in the row closest to the keyboard.
so the reaction of the Computer is no miracle....

i have taken a HD pic of the ram in it original location so i can put them back exactly as they came out and placed them in line next to the Apple anyway.

The RAM-chips are interchangable.....
but they may differ by labelmarking at the top:
4116 - 3 ( -3 = 300 ns is very slow speed )
4116 - 2 ( -2 = 200 ns - nanoseconds - avarage middle speed )
4116 - 15 ( -15 = 150 ns - fastest chips )
so there is one thing to pay attention..... you may change row or position of the chips... but it is important to keep same speed within same row....
if possible each row should keep same manufacturer and same speed.....
so if for example the first row also fails you might instead replace the row with the chips from the second or third row....

if you drag out RAMchips remember to keep those chips in antistatic bag or on antistatic foam .... !

sincerely speedyG

Hello Mike
the purpose of pulling out RAmchips and reseating them back while testing is to detect WHICH chip is bad... and to at least keep the working ones remaining on the board...... by changing rows you can detect which row of chips are O.K.
by changing chips within the rowposition you may detect the single chip bad....

Hello Mike,
i´m still adding edits to the post 2 posts above.....
but yes your correct ... you can eliminate the bad chip by testing....
if you are not able to get at least the first row working then the problem occurs at the databus or the adressing bus
as explained in the first posting... in that case we have to go back to post one and continue into another testing branch...
speedyG

Hello Mike,
of course the character ROM could turn out to be bad, but that would cause other kind of mistake in display....
the graphical blocks indicate that the computer crashes while booting.... the bootprocess completes with a clear screen and the line "APPLE ][" or "APPLE ÜÄ" at the top and
a Prompt "]" blinking below.....
speedyG

Hello Mike,
yes i have....
i have been from 1978 till 1986 the local hardware freak in our Apple User Club Europe ( with more than 350 local members ... )and i have repaired several hunderds of computers from II and II+ up till IIGS..... I believe i have seen nearly every kind of mistake a Apple can generate.... and i am still able to draw the entire circuitplans of any Computer out of the II-series by mind without viewing the plan itself..... If you went to my website ( link was above )
you would find out that i have the entire line of II-series by my own at home...
i have also built 3 or 4 clones from the empty PCB up to working units....
so my explenations always follow up to my experiance of the most common mistakes first and then examining the more rare kind of mistakes....
speedyG

Hello Mike,
in fact this is not realy a problem, because the most Apple computers only require very less power at - 5 Volt ( less than 400 mA ) and most powersupplies have at -12 Volt 0,5 to 0,6 Amps ... so its very easy with simple soldering of few wires to extract the needed - 5 Volt by adding a 7905 powersupplychip ( it can regulate up to 1 Ampere ) and 2 capacitors with 100 nF to the - 12 Volt line and picking up the -5 Volt from the IC chip.... the chip must just be supplied with ( electrical isolated ) coolingsink....
speedyG

Not to elongate this or create a pissing match, but I've seen many electrolytic caps explode.
Not always from old age, but also not from lightning.
My own Imac had caps that exploded and it was a 2006 model.
Another Imac G5 did the same.
Neither saw lightning.

The pulses these caps see is far beyond what a linear supply's caps would have to deal with.
Some of these older caps are only rated at 85C too.
As they age, they become more like resistors. Their ESR changes.
So they get hotter and hotter and don't always vent from the top or push off their cans when they die.

It should also be noted that the current trend is to use multiple caps (like the Imacs.)
This is ok at first, but can create an avalanche effect of failure.
Some start going, then others follow.
But keep in mind that while capacitors have gotten smaller vs their voltage ratings, current still needs size.
I used to repair video monitors and despite a cap being the correct mfd and voltage, too small a size would explode.

Well we had a power cut last night as the Apple II was on and then the power came back on ...now the Apple II doesn't , blank screen that flickers when power is applied...

bad to worse....

..... that was the reason that i recomended to exchange the bridgereticifier too....
it´s under normal ciscumstances not solved by only exchanging the capacitors.... the shortcut usually damages other parts that much too that thay fail short time after the PSU is backup again....
so were back to my advice and link above......
otherwise if you use longer wires for soldering an adaptorcable ( see also link above given ) you could at least continue testing with a PC-Power Unit .....

as i explained above usually the bridge reticifier gets a shot too and soon fails afterwards by creating a shortcut...
sorry that this experience has confirmed again....
before continuing with another PSU at the motherboard please check the mainboard first for shortcuts or damaged Circuits ( topside or printing on it changed color as result of high temperature or bad smell of circuit... )

an now just besides to Neon Forests....
first remark.... neither of the posts given by you above bring up the user one single step ahead in solving his problem....
second remark... if you really like to startup academic discussion about manufacturing problems and mistakes that can occur with electrolytic caps your invited to join the thread:
http://www.applefritter.com/content/capacitor-handling-and-mistakes-and-details-manufacturing
i´ve opened that thread and you are invited to add there your comments ....
unless you have some constructive steps to bring this apple II up to run again plaese leave your comment in the other thread .... thanks a lot....
sincerely
speedyG

Hello Mike,
just added some remark to Neon Forest...
the bridge reticifier is within the PSU and is used instead of the usual 4 Diodes to change from ~ to polarized current with + and -. In the Aztec powersupply ( european version ) it´s located at the marking "DB1" between the 2 vertical coils that are covered with shrinking material.....

the voltages look correct but that must not be also correct if load is added to the supply and it is not worth anything at all if there is still a schortcut on the mainboard....

another problem in this PSU is the TIC123 at the side of the output and marked as "SCR1".... it is responsible for shortcut-protection of the PSU together with the Transistor Q4 and the resistor R30.....
If there is a shortcut at the output this part of the PSU starts some kind of very high fine chirping noise.....
so my advice remains to try and get a substitute PSU.... here in Germany there is a guy that offers periodically every 4 to 5 weeks at ebay a "heavy power supply" for the Apple II in black case and with ("wrong" linear Plug - not correct for the Applemainboard ) but it´s easy to change that cable and the plug from the bad supply to that unit.... and that unit offers nearly 60% more current at the availiable voltages ( so its thereafter no problem to add RAMcards and more diskdrives to the computer....

hello Mike,
you should not expect to see some kind of real burns.... more likely and common are IC´s the turn out to die as result of heat indicated by a slight change of color on the top of the plasticcase compared with others of the same typ ( manufacturer ) .....
the IC´s usually damaged by PSU mistakes are the bustrancievers
( location indicated by rowalphabet and linenumber of the outside border of the Mainboard )
Adressbus (location H3, H4 and H5 ) Databus ( location H10 and H11 )
and other IC´s "under risk of damage" are at
J1, H1, H2 and F2
and the first RAM-chips to be killed are located normally at
E3, E4, E5 or at D3.
If you want to get familiar with the Apple II circuitplans i recommend to download:
W. Gayler - The Apple II Circuit Description.pdf ( very good circuit description of function blocks ! )
Sams ComputerFacts - Apple II, II Plus.pdf at:
http://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Books/
and at the same link also :
Jim Sather - Understanding the Apple II.pdf
and for good instuctions on locating problems and strategy of repair:
Chilton - How To repair and maintain your Apple Computer.pdf
the last one has repair paths for the II II+ series and a second path for repairs of the IIe.
Gaylor has a very good description of the chips related to the graphics pages.....
but at the moment must understand that the problem is not the graphic page but more the path where the CPU accesses the RAM during boot-process - the graphic display is just the symptom ( of the boot crash ).....
unless you can´t get a straigt and correct boot to the prompt everything displayed is just like a photoshot of memory where the computer stucks up....
sincerely
speedyG

Hello Mike,
it´s more common that not the crystal is the problem but forgetting to adjust the monitor at HSYNC and Hight of picture.....
sincerely speedyG.