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My Apple //e repair - No boot

Clint

Experienced Member
Joined
Aug 3, 2013
Messages
176
Location
Sevenoaks, Kent, United Kingdom
So a couple of years ago I picked up a non-working Apple IIe, it lights up but produces no beep on reset.

Anyway I just stored it for a winter project and this is the winter it gets fixed, so I am completely new to the IIe so I have a massive learning curve, so I thought it best to document it here so I can remember what I have done and also grab some advice.

Last night I did some reading about fault finding and decided just to start with basics. Tonight I measured the PSU outputs and although they are not too bad they seem to be out of spec especially the negative rails.

5v = 5.18v
-5v = -4.85
12v = 12.43
-12v = -11.13

Unfortunately my PSU is riveted so I need to drill them out before going on.

You all think it might be as simple as dodgy capacitors ?


IMG_1338.jpg
 

KC9UDX

Space Commander
Joined
Jan 27, 2014
Messages
7,468
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Lutenblag
Those readings tell me that the power supply is not the problem, at least at this point.

Have you disconnected everything except the power supply from the motherboard? If you disconnect everything, including the keyboard, the board should do a self test.

Which //e is this? The motherboard revision will be helpful.

Have you reseated all the socketed chips?

Is the clock running? Do you get a proper reset pulse?

Do you have a logic probe? Oscilloscope?

Is all the RAM socketed?
 

Clint

Experienced Member
Joined
Aug 3, 2013
Messages
176
Location
Sevenoaks, Kent, United Kingdom
Thanks for the reply, I took a closer look today and the chips are really dirty, so I will remove them all and clean the motherboard and chips and refit them.

Here is a picture of my board it has the part number 820-0001-07 and 1979 on it:

IMG_1349.jpg

Here are the dirty IC legs:

IMG_1354.jpg

I have a ram expansion board, to remove it I took a ram chip off the board 4116 and refitted it where the ribbon cable went:

IMG_1352.jpg

IMG_1353.jpg

I do have an Oscilloscope and Logic Probe, I will clean the board up first and go from there :)
 

Dwight Elvey

Veteran Member
Joined
Jun 21, 2003
Messages
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Santa Cruz
Hopefully the leads are not rotted.
You'll soon know. With that much moisture damage,
you may need to replace sockets.
Dwight
 

Clint

Experienced Member
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Aug 3, 2013
Messages
176
Location
Sevenoaks, Kent, United Kingdom
Well I managed to remove the cpu and all the ROMs clean them and replace them bar one which leg stayed in the socket.

So I now need to replace this rom - 341-0014-E8

That said all the ROM's were pretty corroded, so if I replace 1 I think I would like to change them all.

Some questions, can I replace this with a standard ROM, if so where is the best place to find the images and is there a later set of ROM's I can upgrade to while I replace them.
 

Call-151

Experienced Member
Joined
Mar 16, 2011
Messages
75
Location
Canada
depends on how you cleaned the legs. if not done already, i would lightly sand the legs on each chip, then so do the same on all sockets to ensure conductivity. then reinsert. As for the broken leg. depending on your soldering skills and where it broke off, you can successfully re-solder it and atleast continue with your testing.
 

KC9UDX

Space Commander
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Jan 27, 2014
Messages
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Lutenblag
The simplest way to repair that is to
1) remove the broken pin
2) insert the chip
3) insert a length of wire into the socket where the broken pin was
4) solder the wire to the chip
5) cut the wire

By the way, what you have is not an Apple //e at all, it's an Apple ][ or Apple ][+. Completely different animal. (More desirable generally, than a //e).

A quick search suggests that the ROM images could be found here: http://mirrors.apple2.org.za/ftp.apple.asimov.net/emulators/rom_images/

There are two different sets of ROMs for a ][, as far as I know (there are others here with better knowledge). One does not auto-start, and has Integer BASIC. The other auto starts and has Applesoft BASIC.
 

KC9UDX

Space Commander
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Messages
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Lutenblag
Speaking of which, you can ignore what I said about a self-test. That does not apply to your Apple.
 

Dwight Elvey

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Messages
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Santa Cruz
It depends on where it broke. The problem is that there was moisture on
the lead, for some time. The center of the leads were iron with plating
on the outside ( done quite often ). The moisture caused electrolysis that
corroded the leads. It is likely that the sockets may also have oxide on them.
This will mean that you either replace them or you'll have to measure each
on with an ohm meter or test light. They should be 0 resistance from pin to
board. If inserting and removing the part several times does not give you
contact, replacing the socket is the only option.
I don't know how good your soldering skills are. The board is the important
part. If a beginner, removing a socket is not something you want to attempt.
Should you think your skills are up to it, with many of these older sockets,
the pins are pressed in from the bottom. The plastic can be pried off.
Then, using a pair of needle nose and a clamp to hold the board, one heats
the lead from the bottom of the board. When the solder melts, grab the
pin from the tops and pull it out quickly before the pliers heat sink the solder.
Once all the pins are removed, use a solder sucker to clean the holes.
I often remove sockets intact but knowing how to do that without damaging
the board takes years of practice.
Again, the board is the most important part. If you lift a trace by not timing
the pull at the right time, it will need to be repaired. Do not heat the pin
with the iron any longer than needed to remove the pin.
Use a well tinned iron and lots of rosin flux ( never use acid flux on electronics ).
Dwight
 

Dwight Elvey

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These ROMs can often be replaced with EPROMs. Often, some of the address select
logic is in the ROM as well and may not match the minimal selects on the EPROMs.
One can often make simple adapters by stacking machine pin sockets, three high.
One then removes the pins that one doesn't want to cross connect. There is usually
enough room the add some glue logic, a 7404 or 7400, depending on the decoding
required.
I have done this many times when trying to extract ROM data from pinball machine's
ROMs.
It is easier than it looks.
Dwight
 

Dwight Elvey

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I was looking at the apple 2 schematic. It looks like you could
make a simple adapter. If you were not using the expansion adapter
( not often used ), you can make a simple adapter with no glue logic.
You need to pull 2 pins, #21 and #18 on the center socket. These
can be easily popped out. I have a piece of wood with a hole big enough
to let the pin drop out.
You place the socket over the hole with the solder pins facing up.
I then us a short needle nose pliers to push the pin and they pop out.
For these two pins, on the top socket, I cut the small solder pin in half
to make sure it doesn't contact the bottom socket.
On the top socket, run a small wire from pin #18 to the ground
pin, #12, and a small wire from pin #21 to VCC, #24.
You can now use a 2716 EPROM in place of the ROM.
If you need to use the expansion connector, you'd need to add an
inverter, such as a 7404. You'd remove the wire from #18 and
put an inverter between the bottom #18 and the top #18.
The 7404 also needs VCC and ground pins connected. On a 7404,
you can just leave the unused pins open.
Dwight
 

Clint

Experienced Member
Joined
Aug 3, 2013
Messages
176
Location
Sevenoaks, Kent, United Kingdom
Thanks Dwight, as the pins were quite rotted on a few IC's I have decided to do the following :

Replace all ROM Sockets and ROMS (I might make some PCB adaptor boards for this)

Replace the CPU Socket and fit new CPU.

The RAM Chips were less affected so I am just going to replace all the RAM chips with new Mostek 4116's.

Ill try and get this done over xmas will report back with pictures.
 

Dwight Elvey

Veteran Member
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Messages
4,735
Location
Santa Cruz
If you make a PCB adapter, it makes sense to use a single larger
EPROM and make wires to the other sockets for the enable signal.
You'd only need to do one programming.
If you waste some EPROM space, you'd just need one glue chip to
AND all the selects together ( negative select ) and NAND the external
enable. Then use a single address for each select.
You have to figure where to skip addresses in the data file for the
EPROM but makes the simplest adapter
It would take a 1Meg bit EPROM but they are easily available.
Dwight
 

speedyG

New Member
Joined
Mar 25, 2011
Messages
6
Location
munich
Hello Clint,
at this point: there is a link above that leads to the ROM images.
The Eproms should be 2716.
depending to the programmer you have you may need either those that need 25 Volt programming voltage or those
that will get programmed with 12,5 Volt ( see datasheets ).

Besides the task of "resurection" of an Apple II ist explained step by step at my site at the page:
http://www.appleii-box.de/D04_resurection.htm

and at applefritter i have explained several times some debugging of an Apple II after long time storage...
besides at my site there are several other pages related to the topic...

speedyG
 

Clint

Experienced Member
Joined
Aug 3, 2013
Messages
176
Location
Sevenoaks, Kent, United Kingdom
I initially thought this was not too much of a problem, I’ll just write a compatible EPROM and replace them, however the original 9316B ROM’s were not that standard so I can not just use a 2716 EPROM, the issue is that the 9316B had 3 Chip Select lines, while the 2716 had Output Enable and Chip Enable lines as well as a Program line that needs to be kept high during reads, which looks somthign like this:

Pin 9316B 2716
18 CS Active High CE Active Low
20 CS Active Low OE Active Low
21 CS Active Low Vpp Read High

On the Apple 2 Pins 20 and 21 are shorted, Pin 18 is used to disable all on board ROM’s when an upgrade card is installed in a expansion slot.

So to replace the 9316B with 2716′s we need to invert both Pins 18 and 21. I decided to do this with a dual hex inverter 2704 SMD packaged device. I will create a PCB to do this for all the ROM’s but will test with a birds nest type method first.

The Device I have decided to use is a 2704, a small 6 pin dual inverter:

Screen Shot 2016-12-26 at 10.56.14.jpg

I have never used any PCB design software before so if anyone has some experience can they take a look at this and see if it will work, I will use a piece of through hole development board to test first then I will get a run of PCB's done.

Screen Shot 2016-12-26 at 10.52.31.jpg
 

David_M

Veteran Member
Joined
Oct 1, 2016
Messages
647
Location
Melbourne, Australia
The damage ROM is AppleSoft basic, not integer basic so you will have the autostart ROM which in a working system will clear the screen and in the middle of the top line display "Apple ][" once you have it working.

I'd not worry about that ROM just now, it wont prevent the screen clearing and display, without that ROM you will get the monitors "*" prompt instead of the "]" applesoft prompt.

2716 eproms are not quit compatible, one of the enable lines is inverted. So to use an eprom you would have to isolate that pin (common connection to all the other ROMs) and use a 74ls04 to invert it while leaving the other ROMs not inverted. To avoid that drama the simplest solution it to use a sacrificial chip to donate some legs. Keeping the donor pin straight bend it back and forth with some pliers so it snaps right where it enters the ic casing. Then tin the shoulder (wide) part of the broken pin on the ROM before soldering the shoulder of the donor pin to the ROM. Easy peasy.

Finding the actual problem, is going to be a pain given the condition on the chips and most likely the sockets also.

You can make it a little easier using one of these..
http://www.ebay.com.au/itm/Multi-Fu...528456?hash=item2355ee2f88:g:Xl0AAOSwOyJX36dC

It will test most of the TTL chips on the board and eliminate a lot of potential problems. it won't test the cpu, rams,roms, 8t28 or the 74ls259 or ne558. It can test all the other chips though.
If you dont find any faulty chips, test the RAM chips in another system if you have one that uses 4116. The 8t28's you can easily test with a logic probe.
If having done all that it still doesn't work.... you are in for a hell of a time finding a bad socket.

Back when they were new being sockets made them easy to fix.. now those sockets are a liability. Almost any chip failing in an apple2 will give similar non boot symptoms.

But post a photo of what is displayed on the screen, you might be lucky and have one of the rare faults that gives an indication of the cause.
 

Clint

Experienced Member
Joined
Aug 3, 2013
Messages
176
Location
Sevenoaks, Kent, United Kingdom
Thanks David, there is nothing on the screen and no beep after pressing reset, I will buy a cheap logic tester now :)

I took another look at the EPROM's today and decided as I wanted to change them all the easiest way for me was to convert the Mainboard to run them.
So I disconnected the INH Line from the edge connectors and tied all the pin 18's low for now (I will run an inverter on this line as soon as they arrive).
Then I split all the VPP Lines (Pin 21) and tied them high.

IMG_1404.jpg

I took a read of the ROMS's as they came out, 1 would not read, 1 read but was corrupt and of course I have one with 3 legs off, so this would have needed to be done anyway.
I burnt new set of ROMS into 2716's and fitted them and checked leg to solder side with a continuity tester.

IMG_1403.jpg

I am going to replace all the RAM with new as a lot of the legs have the same issue as the ROMS, most other chips although tarnished seem to have not rotted.


I also took a scope to the 6502 and I have no clock ! - so I guess that's my next step.

IMG_1407.jpg
 

Dwight Elvey

Veteran Member
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Jun 21, 2003
Messages
4,735
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Santa Cruz
Also use the idea of the NOP tester. That and a 'scope can do a lot of debugging.
I'm not a big fan of logic analyzers. If you have a socket for an EPROM, one can
do a lot more debugging with simple code test.
Even with an analyzer, one has to know what the code is suppose to be doing.
One also has to make the useful connections. Test code is much more directed
and controlled.
Using a signal to sync on, one can follow logic much easier with a 'scope.
In years of debugging systems, I've only used an analyzer once and that was
to catch a logic design that happened only once in about three hours.
Even then, I found it to be clumsy and not able to handle the complicated triggering
needed to find the problem source. I had to constantly baby sit it and check
each trigger to see if it were the event I was looking for and then start it again.
The analyzers have gotten better but still have a steep learning curve to be
efficient.
Writing simple code and a two channel 'scope are all you need.
Dwight
 

Clint

Experienced Member
Joined
Aug 3, 2013
Messages
176
Location
Sevenoaks, Kent, United Kingdom
Well today I cleaned up every IC and reseated, I also replaced all the RAM with new.

I went on to look at the clock, I have no 1mhz clock at pin 37 of the CPU.

I took a look at the oscillator and surrounding IC's:

The Oscillator works:

B2PIN10.jpg

However the input to B1 looks slightly different at the bottom of the waveform, odd because the schematic shows these directly connected.

B1PIN9.jpg

The Video Generator Output looks correct:

Pin 3:
B1PIN3.jpg

Pin4:
B1PIN4.jpg

But the CPU output isnt there:

B1PIN7.jpg

I also noticed that C2 Was running very hot:

FLIR0217.jpg

So anyone got any ideas, I dont have replacement IC's here so need to order some, but pleased I can see an issue :)
 
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