Chipper Checker Adapter
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These instructions are for building the special adapter needed for the following Thomson television chassis; CTC174, CTC175, CTC176, CTC177, CTC184, CTC186, & CTC187. These chassis's do not incorporate an interface connector to allow Chipper Checker connectivity. This project shows you how to build an adapter that will clip on the top of the EEPROM U3102 and plug directly into the Chipper Checker interface box.
Parts needed are
1....... 3M part# 5108 or equivalent 8 pin dip IC test clip
2....... 1K 1/4 watt resistor
3....... 1 PS-2 Keyboard extension cable
(Fig 1) is the 6 pin PS-2 connector used to connect the Chipper Checker interface box to the television chassis. This connector can have either a 3 or foot 6 wire cord attached to it. Only 3 wires will be used in this project. I was able to get these cables for about $6.00 through Comp USA. Any computer specialty store probably has generic PS-2 keyboard extension cables for under $10.00. The wires needed are connected to pins 1, 2, and 3. The interface cable is made by cutting off one end of this extension cable.
This schematic in (Fig. 2) shows how the simple interface adapter connects to the EEPROM in the television. The number on the the right side of the schematic relates to the pin numbers of the PS-2 connector shown above in Fig. 1.
* Illustrates that it is possible to initialize an EEPROM even if it is removed from the television.
Wired IC TEST Clip.
Disregard the colors of the wires in (Fig 3). The wires in my cable assembly may be different that yours. You will need to identify the wires by an continuity check. Compare the photo (Fig. 1) of the PS-2 connector numbers and referencing them to the white numbers in (Fig 3). The cable will connect to the pin assignments listed in black on the top of the IC test clip. This photo is the top part of the IC test clip.
Note: I suggest to file notches in the corner of the test clip that relates to pin 1. This way there is no guess work in connecting it the EEPROM that needs initialization.
Refer to Fig 3 & Fig 1 to see how the cable connects to the IC clip.
Pins 1, 2, 3 & 7 of the test clip are vacant.
Pin 4 of test clip is connected to Pin 1 of the PS-2 connector.
Pin 5 of test clip is one end of a 1K resistor, and Pin 3 of the PS-2 connector.
Pin 6 of test clip is connected to pin 2 of the PS-2 connector.
Pin 8 is the opposite end of the 1K resistor.
If desired to apply external B+, it can be supplied to this test clip by connecting Pin 8 to +5 volt, and the ground to pin 4.
Note: I suggest that you strain relief the cable can be accomplished by tightly wrapping a nylon wire tie at each end of the wire going into the clip, and another where the wire enters & exits the test clip.
Dennis Viereck E-mail
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