Osborne Vixen - Zenith 7" display t-shooting issues

Chuck, my friend... On Mon, Nov 3, 2014 at 3:59 PM, Chuck Guzis <cclist at sydex.com> wrote: You may have cracked one of the tougher nuts, sir! Now check this out.. When you quoted the HOT for the DT12 chassis as part # 121-1039, that 1039 seemed an awful lot like 1070 to me. So on a hunch, I punched "zenith 121-0170" into Google - and guess what? The Zenith 121-1070 is in fact a high voltage, high-speed switching transistor. As mentioned previously, it's an in-house Zenith part number, which probably includes several different but similar devices that all fall within the same specs. Per the manufacturer, it is suitable (among other apps) for deflection circuits. A little more searching (eBay helped) turned up that it crosses to the NTE 379 - just as does the HOT in your Zenith DT12! I think it's safe to say that the HOT in the Osborne Vixen Zenith display is a "Zenith 121-1070".. which apparently subs to the same NTE / ECG 379 part. Very slick.. Data sheet for the 121-1070 / NTE 379 calls out a beta of 8-10 min. and 30-40 max. So that leads me to believe that the original 1070 HOT may, in fact, be OK - and the issue is to be found elsewhere in the circuit. It's not a for-sure, as the part might be misbehaving under actual circuit conditions - but at least I have some confidence that we know what it's supposed to be. Thank you.. *** GOLD STAR FOR CHUCK!! ***