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Author Topic: Apple II+/IIc/IIe/IIgs/III Computers  (Read 15145 times)

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Offline channelmaniac

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Apple II+/IIc/IIe/IIgs/III Computers
« on: May 04, 2014, 06:45:03 PM »
Subject: Diagnosing RAM errors on Apple IIc/IIe

The Apple IIc and IIe computers have built in diagnostic routines that can be enabled by pressing the Ctrl-Open Apple-Closed Apple-Reset key combination. Depending on the system ROM it will either emit a high pitched squeal followed by a series of high resolution colored screens or will have a series of low resolution colored blocks.

If yours has the series of low res blocks then it will have the newer ROMs which will do the test much faster to completion.

If an error is found there will be a set of 8 zeros and ones. Where there is a 1 it will point to a bad RAM IC on the motherboard.

If there is an asterisk (*) next to the numbers it signifies that the bad RAM is in the 64k to 128k upper memory range on the Apple IIc or on the 80 column card in an Apple IIe.

Run the test again after replacing the bad IC. Do not be surprised to find additional RAM chips that are bad! The test stops as soon as it finds a bad chip so the test will have to be run again and again until it tests with no errors.

If you want to do a continuous memory test to "burn in" the system simply leave the keyboard unhooked from the logic board and it will run continuously.

Enjoy!
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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #1 on: May 04, 2014, 06:45:17 PM »
Models: Disk II and 5.25" Uni/Duo Disk drives
Symptom: Drive continuously runs. Any disk inserted gets erased.

This happens if the disk drive cables get hooked up backwards. Replace the 74LS125 IC on the Disk Drive's internal controller board.
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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #2 on: May 04, 2014, 06:45:29 PM »
Model: Apple II+/IIe
Symptom: Will not power on

Replaced a 22ohm resistor & a nearby small electrolytic cap in power supply. This is a common problem on the non-Astec model supplies.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #3 on: May 04, 2014, 06:45:42 PM »
Model: Apple II+/IIe
Symptom: Dead - no power.

Power supply tested good. The +12v line was shorted to ground causing the power supply to shut down. Replaced a shorted monolithic cap on the +12v line to fix.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #4 on: May 04, 2014, 06:45:54 PM »
Model: IIc/IIc+
Symptom: Floppy disk will not spin or read

Replaced the defective IWM (Integrated Wozniak Machine) IC. This IC controls the floppy disks and is prone to dying if the drives are added or removed with the power on.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #5 on: May 04, 2014, 06:46:54 PM »
Apple Custom Chip Numbers can be found in a text file in the downloads section of http://www.arcadecomponents.com

These numbers include PALs, HALs, ROMs, PROMs, EPROMs, and custom logic chips.

If you know of any that are missing, please PM me through the board and I'll add them.
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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #6 on: May 04, 2014, 06:47:12 PM »
Model: Apple IIgs
Symptom: Dead keyboard & mouse

This actually has two different causes/repairs.

The first is to open up the keyboard and repair cracked solder joints on the ADB (Apple Desktop Bus) ports.

If that's not it the second is to replace the 8 pin square black plastic filter network on the IIgs logic board. It is situated next to the ADB port on the back corner of the motherboard. It has 4 toroid core filters built into it. If one of the 4 filters has no continuity then the ADB port will be dead.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

http://www.arcadecomponents.com

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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #7 on: May 04, 2014, 06:47:24 PM »
Model: Apple II+/IIe Power Supply
Symptom: Dead.

This was the Astec version of the Apple II Power Supply.

Replaced a blown 2.75A metric size fuse and a shorted bridge rectifier. Bridge rectifier can be replaced with an NTE5319 but it will require the holes in the board to be enlarged to accomodate the larger legs of the replacement device. This replacement device has a higher current rating and should last longer than the original part.

Replaced C7, a 10v 220uf 85 deg C capacitor with a 16v 220uf 105 deg C capacitor. This cap is a common failure item and should be replaced in any Astec version Apple II+/IIe power supply.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #8 on: May 04, 2014, 06:47:54 PM »
Model: IIe motherboard
Symptom: Dead. Garbage on screen.

Checked the activity on the DRAM legs with a logic probe and found they were pulsing in slow sync which was an odd pattern. Replaced the 6502 CPU and ran diagnostics on the board.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #9 on: May 04, 2014, 06:48:06 PM »
Model: Apple II+/IIe power supply
Symptoms: Makes funny noises. Does not work.

Power supply was not an original Apple supply but rather a clone. Found 3 burst capacitors and 4 leaking capacitors in the output section. Replaced the bad caps and tested the rectifiers for shorts. None were found shorted. Reassembled and tested the power supply.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

http://www.arcadecomponents.com

Offline channelmaniac

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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #10 on: May 04, 2014, 06:48:45 PM »
Model: Apple II+
Symptom: Dead, Screen full of @, #, and $ symbols

Removed a 64K DRAM chip that was plugged into the DRAM socket the language card normally plugs into. This is an incorrect chip (5v only... The 16K chips are +5/-5/+12v) and was getting red hot. Replaced every 4116k DRAM as they were all blown - 23 dead DRAMs (the 24th chip being the incorrect 64k chip). Replaced a bad 74S86 at location B2.

The system would then try to boot but would fail. The address lines on the DRAMs were incorrect. Two were dead, 1 was stuck high, and 1 was racing. Replaced bad 74LS153 chips at E11, E12, and E13 to fix. Now the system would boot but drop down to the Monitor ROM. Replaced the D8 and F0 ROMs and burned in the board for several hours.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #11 on: June 05, 2014, 08:50:25 PM »
Model: //c
Symptom: Dead. Blocks on screen.

Replaced bad 65C02 CPU, ran the built-in tests, and tested the floppy drive.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

http://www.arcadecomponents.com

Offline channelmaniac

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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #12 on: June 06, 2014, 08:13:03 PM »
Model: //e
Symptom: Dead

Board had physical damage to the CPU socket and 1 resistor pack.

Replaced missing CPU, CPU socket, broken resistor pack, and the socket on the 74LS10 IC. Replaced defective HAL chip. Tested.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

http://www.arcadecomponents.com

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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #13 on: September 07, 2014, 07:00:11 PM »
Model: Apple IIgs
Symptom: Dead

Replaced bad 470uf @ 16v, 2x 1uf @ 50v, and a 10uf @ 25v cap that had high ESR and replaced an open 100K ohm 1/2w resistor in the power supply. Ran built-in diagnostics and tested the floppy drive port.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

http://www.arcadecomponents.com

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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #14 on: September 15, 2014, 07:38:24 PM »
Model: Apple II+
Symptom: Random crashes

Reseated bank 1 RAM (tarnished legs), reseated multiple chips that were raised up in their sockets, tested the ROMs and D8 was bad. Board would boot but would not recognize all of its RAM. Replaced bad RAM at D10, and reseated the 74LS194 at B4 as pin 8 (ground) was outside its socket. Ran memory tests and Apple DOS 3.3.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #15 on: September 15, 2014, 10:06:28 PM »
Model: Apple II+
Symptom: Dead. Garbage on screen

Replaced 4 bad RAMs in bank 1 at C4, C7, C8, and C9. Replaced bad 74LS11 at B12 that had a weak output. Replaced 2n3904 transistor and ran RAM tests. Replaced bad RAM in bank 3 at E10.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

http://www.arcadecomponents.com

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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #16 on: September 15, 2014, 10:17:12 PM »
Notes: Apple II+ memory test:

Open the monitor by typing: CALL -151<ENTER>

Type in the following (with a space at the end before hitting <ENTER>!!!):
C050 C053 C054 C057 N 265:FF N 266<265.BFFEM 266<265.BFFEV 265:0 N 266<265.BFFEM 266<265.BFFEV 34:14 <ENTER>

The screen will show graphics at the top with text at the bottom and will alternate between a black screen with ? for the bottom four rows and a white screen with inverse @ symbols for the bottom four rows.

Watch the screen carefully! If it finds an error, it will flash the text on the screen just before it switches to the next test. The error will look like this for example: 8000 (FF) 7F   where the 8000 is the address, FF is the data written, and 7F the data read.

Addresses: 0000-3FFF = Bank 1 (chips C3 - C10) = 0 to 16k
Addresses: 4000-7FFF = Bank 2 (chips D3 - D10) = 16 to 32k
Addresses: 8000-BFFF = Bank 3 (chips E3 - E10) = 32 to 48k

Data lines start on the left. 7F in the example is 01111111 in binary. The 0 is the bad bit in this example and is the upper most data bit. Reading from left to right, the upper most bit would be the chip at position E10

Enjoy!
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

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Offline channelmaniac

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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #17 on: September 16, 2014, 06:57:59 PM »
Model: Apple II+
Symptom: CTRL key not working

Replaced bent pin 23 on the keyboard to controller board connector and tested.

Note: Pin 1 on the socket is unused and is a spare pin that can be taken to replace a bent one.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

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Offline channelmaniac

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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #18 on: March 14, 2015, 11:40:03 PM »
Model: Apple IIe
Symptom: "-" key not working

Keyboard had physical damage. Replaced bad key switch and missing key cap. Tested
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

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Re: Apple II+/IIc/IIe/IIgs/III Computers
« Reply #19 on: March 14, 2015, 11:40:42 PM »
Model: Apple 3.5" drive
Symptom: Intermittent read errors

Cleaned and lubricated drive. Tested
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

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