I've got an HP-150 which just developed a video problem. Any chance
the TechRef is downloadable somewhere?
http://hpmuseum.net/collection_document.php
abut half way down is the 150 service manual. My 150 also has a video
problem. Diagnosis is "aided" by flashing LED's on startup. This is
supposed to show which memory location is faulty. I havnt had time to
investigate further.
roger