The Museum of HP Calculators
HP Forum Archive 19
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|Update:9100A with no display|
Message #1 Posted by Richard Wilder on 15 Jan 2011, 7:25 p.m.
Still no display... I've verified the KB as OK. Probing on the core data board I found that D3 is not pulsing. All other Dn's are pulsing at the respective sense amp output transistor collectors (labeled D(n) on the schematic.) The inhibit FF's (F20 - F25) are all toggling except F25 which is D3's inhibit. K25 is toggling but J25 is not. J25 is the OR of BAddrE' and SC4 and a couple other signals. BAddrE' and SC4 are both toggling but at any given time one is a logic 1 so J25 is stuck at 1 (0V). And now I'm hoplessly lost... ;^P
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