UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

TonyDuell · 26th Jul 2022, 5:02 am

I would try removing link W1. The techref makes it very clear you have to do so, the ALE signal will not behave properly if driven from 2 sources (the coprocessor board and the original 8088 via W1).

No idea why there's resoldering on the IC next to the coprocessor socket. That's the 'Elmer' ASIC, real time clock + baud rate generators +... Very early machines have 50 pin header in place of it, then a daughterboard fitted. Perhaps your Elmer IC was replaced at some point.

As for the printer, the one for the orignal HP150 won't work in a 150-II. There's a special interface circuit for it on the 'frontplane' (the PCB that interconnects the other boards) and a power connector for it on the PSU board. Your best bet is to find another Thinkjet with a good flexiprint (any interface version) and to swap the flexiprints or to have one made (are there companies that do that?)

26th Jul 2022, 5:02 am	#29
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,225	Re: HP 150 Touchscreen II repair I would try removing link W1. The techref makes it very clear you have to do so, the ALE signal will not behave properly if driven from 2 sources (the coprocessor board and the original 8088 via W1). No idea why there's resoldering on the IC next to the coprocessor socket. That's the 'Elmer' ASIC, real time clock + baud rate generators +... Very early machines have 50 pin header in place of it, then a daughterboard fitted. Perhaps your Elmer IC was replaced at some point. As for the printer, the one for the orignal HP150 won't work in a 150-II. There's a special interface circuit for it on the 'frontplane' (the PCB that interconnects the other boards) and a power connector for it on the PSU board. Your best bet is to find another Thinkjet with a good flexiprint (any interface version) and to swap the flexiprints or to have one made (are there companies that do that?)