Board Repair - Page 2
6802/6808 Adapter for HP Logic Analyzers
In August 2009, I made an adapter to easily connect my logic analyzer to the address, data, and control lines of the CPU chip. It allows complete access to the operation of the CPU board core. This board is a modification of the 68B09 adapter from the WPC project.
Adapter board in operation on a System 11 board. This allows me to
accurately trace the program execution and better find what is wrong
with a board.
Typical view of Logic Analyzer connected to a CPU chip. The last two lines
are spare signals that the user can clip to the board (blue clip in image above).
Testing Power Supply Boards
I also built a test setup for the System 9/11 power supply boards. They include an AC multi-output transformer (left) for feeding the low voltage sections, and a connection to my variable transformer for the high voltage circuits. This latter arrangement allows me to turn the input voltage up gradually to prevent damage in case of a fault, and allows me to check how well the board regulates the output high voltage. These plug into the unusual 3x4 pin 3J1 connector.
Some early System 3-7 CPU boards use 2532 ROMs. These are similar to 2732s except for a slightly different pinout, and were originally made by TI. My PROM programmer, the Dataman S4, does not have an entry for the 2532, so I decided to make adapters to program these ROMs. I used a wire-wrap socket and a conventional socket stacked on top of each other. This is shown on the left in the image below. I found that using the Toshiba setting for the 2732 worked best on my Dataman.
and using a 2732 into a location meant for the 2532 (right).
Other CPU Testers
February 2006, this System 3-7 tester (6253871562) was $665+$70.
Close-up of the control panel of the above tester.
Feb 2006, this System 11 tester (6254290420) was $366+70.
It looks home-made.
Close-up of the test panel. Note lack of solenoid and lamp matrix displays.
Feb 2006, this System 3-7 unit (6255704954) was $474+shipping.
Closeups of the test panel.
Video of System 3-7 tester in operation.
February 2007, this WPC95 tester (110093911411) was $1500.
The I/O panel looks like it includes a matrix of lamps (similar to my tester),
and a matrix of switches. One can also see test lamps for solenoids and other
Close-ups of the above WPC95 tester.
September 2007, this System 3-7 tester sold for an amazing $1200
In March 2008, this System 3-7 tester sold for $515 (160213461303).
It is highly incomplete.
April 2008, this System 3-7 tester was $688 (130209246482).
June 2008, this System 3-7 tester was $236 (320258934586)
It was missing its boards and the upright panel.
Sept '08, this System 11 tester sold for an amazing $1435 (120300193798).
I am always amazed how much these units sell for compared to my tester.
Nov 2008, this System 11 tester (110312219131) was $550.
July 2009, this System 3-7 tester (140329614857) was $500+$50.
Oct 2009, this System 3-7 tester (250506825123) w/o driver board
was $160 (IL pickup only).
Oct 2009, this WPC89 tester (250506810477) was $635 (IL pickup only).
In Dec 2009, this new WPC89 tester (320457377514) was an amazing $3900.
In March 2010, this WPC-95 tester was $2600 (280476266131).
April 2010: This System 3-7 was $560 (260579868990).
- Leon's System 9 test page.
- Hard to find CPU parts at GPE.
- Okaegi's System 6 tester (scroll down "Williams part").
- Pinout of DE-9/DB-9/IDC RS-232 connector.
- Debugging sound on System 9 (photo of setup).
- System 6 Schematics.
- Mark's guide to Williams System 3-7.
- October 26, 2005 - Purchased first nonworking CPU board for $40 + $10. Previously, I had seen untested units on ebay in the range of $31 (burn damage) to $175 (clean).
- November 7, 2005 - Initial checkout complete. Board is mainly working. Only K1 still missing (on order).
- November 10, 2005 - Completed initial breadboard concepts for CPU tester.
on RGP regarding this device.
- November 25, 2005 - Initial layout of circuit board complete.
- November 26, 2005 - Purchased a second nonworking CPU board for $23+$14 on ebay. When powered up, it passes CPU self-test, and lamp matrix works fine. Further testing in the future.
- December 01, 2005 - Arrival of the finished CPU tester boards.
- December 03, 2005 - Initial testing of the CPU tester complete. Lamp matrix, switch matrix and LCD interface operational.
- December 11, 2005 - Software development of the Microprocessor in progress.
- December 26, 2005 - Software development mostly complete. Kit is made available.
- January 13, 2006 - Initial orders and parts are in. Manual is half written. Assembly of first round of units begins.
- January 21, 2006 - Initial orders complete and ready to ship.
- February 1, 2006 - First use of tester to repair a CPU board.
- February 19, 2006 - A nice endorsement
from Peter regarding the CPU tester.
- February 20, 2006 - Auctions for
testers on ebay.
- March 14, 2006 - Due to popular demand, I built a second batch of testers.
- March 24, 2005 - System 11 compatibility added.
- August 7, 2006 - First unit sells with BIN on ebay for $500 (item #170016357842).
- July 2, 2007 - Case #6 documented.
to MOSFETs for the high-side lamp matrix driver.
board was bought on Ebay for $35 (+$15).
- August 2009 - As of this date, I have successfully repaired more than 50 System 9 and 11 boards. I am glad to say that despite the varied challenges (battery leakage, burns, failed parts, etc), I have not failed to repair a single one. That is about one board per month since 2005.
- August 2009 - Made adapter board
connect Logic Analyzer to a 6802/6808 CPU chip.
- May 2010 - Added System 3-7 mode to CPU tester.
- October 2011 - Added power supply test fixture.
I have several repaired System 9 and 11 boards for sale,
I also repair these boards. Please contact me for details.
(c) 2009 Edward Cheung, all rights reserved.