Errors in QL Service Manual

[RWAP]

A customer has been investigating the differences between his issue 5 and issue 6 motherboards in his QLs and believes that there are errors in the Service Manual relating to the issue 6 motherboard.

It may also indicate what the HAL chip is for on the issue 6 boards!

1. The circuit diagram shows the ZX8302 data bus connected to the "in side" of 74LS245 - whereas on his issue 6 board, this is actually connected to the "out side".

2. Data buses (inside by ZX8301, outside , 74LS245) mastering is incorrect in the service manual.

3. The circuit diagram shows a 74LS03 chip which isn't on the motherboard - instead there is similar logic in the HAL.

4. Ground point of R90 is very bad located in the issue 6 - which may cause a bad PAL picture. We could correct that by wiring R90 ground to the pin 15 of MC1377.

Can anyone confirm?

The QL Service Manual appears at: ftp://ftp.worldofspectrum.org/pub/sincl ... Manual.pdf