Hi Does anybody have a QEP3 Programmer that I could purchase or lend me.
Being trying to repair mine, without much luck since I cannot find a circuit diagram for it. Have been trying to trace the circuit which has not been easy. Double sided card with not a great layout. Also the PCB is not of very good quality, tracks lift so easy. Been repacing the logic chips, one by one, by fitting IC sockets. Managed to find replacement EF6821 chips, but the originals seem to be OK. As far as I can tell. The original fault was a short between the TIP31 transistor and LM317 voltage regulator heat sink tabs. Due to a poor fitting mica insulator, whcih put nearly 7V on the 5V logic chips. The card boots up with the EPROM command, and the firmware does seem to work. So some of the addressing and 74LS254 direction does seem to work. In am now gettting the right hand EF6821 to be addressed, but not the left hand one. Built a test jig to address the address logic, and all the chips are working. I am now concerned I have have missed a track which I have damaged in fitting the sockets, which I have no way of tracing. Even though I did this one by one. Also traced the circiut before replacing chips. I am not getting addressing at each stage if the test routine from the firmware. Which I think I should to change the voltages and pins being addressed on the EPROM socket. The left hand EF6821 seems to the chip that does the EPROM pin selection. If anybody can help, please contact me on my e-mail address. Thanks Ian Burkinshaw _______________________________________________ QL-Users Mailing List http://www.q-v-d.demon.co.uk/smsqe.htm
