Apple IIGS repair help needed

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Apple IIGS repair help needed

Hi everyone,

I'm stuck with one of my Apple IIGS.
It started, when I received my Transwarp GS card. The card seems to be unstable and I've found out, that the connector to the CPU socket seems to have connection problems. So I replaced the CPU socket with a new one on the GS board. Then my problems started Smile

When switched on, it displays only a white screen with a black border, regardless of what I am doing. There is no sound either. I've already switched chips from my other GS, but nothing seems to help. When I check the CPU with a logic analyzer, there seems to be "normal" activity.It even seems to respond on a reset via keyboard.

Has anyone a hint for me?

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Re: Apple IIGS repair help needed

Hello vintagebytes,
sounds to me like, while desoldering the damaged socket, that the solering iron
has been kept too long periods and too hot tip at the mainboard and it got "fried"....
do you have some hires pictures from top and from soldering side
( at least 3000 x 2500 pixels ) ?
speedyG

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Re: Apple IIGS repair help needed

Thanks for your answer!
Sorry for my delay in responding. Normally, I know, what I do when soldering, I've soldered several computers, mostly SMD. This ought to be a "normal" replacement, but now I'm stuck as I have no real experience with the GS. I can provide photos, when I'm at home, no problem.
Oh, btw. I think we already met at VCFe in Munich some years ago. I was the guy with the Commodore plus/4. Do you plan to go there this year, too?

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Re: Apple IIGS repair help needed

Hello vintagebytes,
the participation is dependent to the current health issues.....
and to posssible transportation of the expo stuff....

no problem with the delay of taking the pictures.....
its just the problem that i can´t view the problem - then i can´t spot the possible issue...

at the moment i just can explain the background of the issue...:

At the IIGS mainboard Apple started first time to "bond" the placed parts ( sockets and IC´s )
with a "laser beam shot" at the 2 opposite corners....( previous of the wave soldering of the board
with pupose to keep parts in place while board is moved along the productionline )

this results to 2 opposite pins not beeing soldered - but rather more beeing "welded" with the mainboard.

You recognize this by the fact that while desoldering - it´s nearly impossible tho suck out any soldering
material at that 2 pins ( due to missing higher heat )of the part. While desoldering this generally
leads to the mistake, that the throgh-hole connector ( a kind of mini metal sleeve ) at this pins gets
destroyed and removed with the pin -

resulting to a missing connection between top layer and soldering layer or to damage of the related
traces.

So it´s highly recommended to inspect very carefully the corner pins for such damage.

speedyG

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Re: Apple IIGS repair help needed

Hi SpeedyG,
so, best would be to check the "corner pins"? As I've already checked, that the CPU seems to do some work (so I assume, that +5V and GND (pin 1 and 21) are okay) and the reset line (Pin 40) is triggered, when I try to reset the GS via keyboard.

I will check Pin 20, which is A11 line. I noticed, that two wholes were hard to desolder, but I could not remember, that there was any damage. Normally, I'm very careful on soldering Smile

I will be on the VCFe this year. I want to show my GS with a Lego interface. So, what's better than one Apple II? Two Apple II Smile If I make this board working again, I will bring two GS to Munich.

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Re: Apple IIGS repair help needed

Maybe we can meet there if i can manage the transportation...

like mentioned above the problem splits apart to 2 issues:

damaged connection at either the top side of the PCB or the soldering side of the PCB

or damaged trace at that pin on either topside or at solderside.

Bear in mind that the fact that the supply voltages and GND are present at the CPU does not give
guarantee that a supplyvoltage leeding from the pin by a damaged trace to another pin of another IC
won´t be damaged leaving that IC without supplyvoltage......

therefor you should inspect very carefully also that pins at both sides ( top and soldering side ),
that are assumed at the moment to be O.K. ....

and similar is of couse also valid to the A11 line....

even when the trace might look visualy O.K. there might be a micro tearoff.... it is therefor recomended
to doublecheck a safe connection with a multimeter and also check possible connection to the
neighbor pin for possible shortcut....
speedyG

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Re: Apple IIGS repair help needed

Okay, I've checked the soldering points. All have contact as expected. I do not see any damages, that could cause a problem here. No via seems to be broken or is missing...

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Re: Apple IIGS repair help needed

If that would be true - the computer would be working - correct.....?
maybe 4 eyes can see more then 2 eyes...
probably it´s a good idea to take good hires closeup pictures ( that permit me to zoom in )
like explained in previous message...
take a short view to the pictures at this thread:
http://www.applefritter.com/content/faulty-ii-plus-motherboard-wont-boot-garbage-or-nothing-screen
as example for good closeup pictures....
speedyG

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Re: Apple IIGS repair help needed

So, why should I lie?
I've checked all Pins on CPU socket, they all have contact.
I can pull the CPU and the Rom from the board and it will still display the white screen with a black border. So, I'm not really sure if this is really CPU socket related. Could there be another issue? Anything, that I can check?

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Re: Apple IIGS repair help needed

I didn´t say that i accuse you.....
i just state that malfunction does not certify your statement sbout working connections.....
and the question about checking the other items.... ?

well 2 questions:
did you touch anything else at the mainboard with the soldering iron?
and the second question splits into 2 parts:
is your soldering iron antistatic decoupled ( meaning that the tip has antistatic protective ground ) ?
( check that in documentation of the soldering iron )
did you take action of protecting the mainboard against static damage while soldering ?

if not - well - then any static sensitive devicepart of the mainboard might have been damaged while soldering
starting with the RAM...... and continuing with the VLSI chips....

speedyG

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Re: Apple IIGS repair help needed

I am using a Weller WD1 soldering station and it's grounded. All work is done on an antistatic mat, there should be no problems here.

So, I will check the standard and fast ram. I think, that I've a couple of spare ICs to replace them.

Oh, could it be a problem, that there is no battery on the board?

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Re: Apple IIGS repair help needed

Hello vintagebytes,
in normal condition the missing Battery should not be a problem,
it just would result to the fact that the system "forgets" the
setup and date in the options panel after every power off -
while with battery it would keep that settings.
But if the Battery has been removed you should ensure that there is
no shortcut left by the removal.

And for primary testing it´s recommended to test without any card inserted to ensure
that not a involved card is causing the trouble.

If then poweron is working correct with completion of the boot process - then you may add
step by step the cards back to the system.

sincerely speedyG

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Re: Apple IIGS repair help needed

I am using a Weller WD1 soldering station and it's grounded. All work is done on an antistatic mat, there should be no problems here.

The question was not related to the grounding of the electronics in the station
- but rather more to the grounding of the soldering tip....
some tips aren´t protected there....
speedyG

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