Z88 Service Manual
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3. REPAIR

General

Renewal of components should be carried out using recognised desoldering/heatsinking techniques to prevent damage to the component or to the printed circuit board. Note the following points:

EPROM Substitution

It is possible that some service centres may wish to replace the 1 Mbit ROM compatible EPROM with EPROMs conforming to the JEDEC pinout. This requires a small modification to the board involving the interchange of pins 2 and 24. This applies to both the Z88 and the EPROM PACK. In order to modify the Z88, proceed as follows:

In the case of the EPROM card, add external wiring to transpose pins 2 and 24. A summary of the action required for the various manufacturers' products is set out in the table below.

EPROM Type Swap Pins 2 and 24 on 128k EPROM card? Modify Z88 or OKAY as is? ROM or JEDEC?
Toshiba
TC571000D-20 YES MODIFY JEDEC
TC571001D-20 NO OK ROM
NEC
uPD27Cl000D-20 NO OK ROM
uPD27Cl00lD-20 YES MODIFY JEDEC
Hitachi
HN27Cl0lG-20 YES MODIFY JEDEC
HN27C301G-20 NO OK ROM

NOTE: The NEC and Toshiba parts are opposite types but with similar part numbers.


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Fault diagnosis Repair Parts list