techtronix 475, U370 does not work?

[cmcdan]

Hi, Hope to get some info. I am a long time Tek repairman but stuck here. The manual, p26 has a logic chart for U370 inputs. I removed U370 and checked  the 4 inputs; logic is correct but U370 does not output signal. I used hairpin loops to bypass ch 2 and all's well. The voltage level hi -2.30; low - 1.49; This IC had a heat sink; it gets warm but not hot? What to do? cmcdan  solution: bought a replacement from Greece, yes the country. It worked but scope died; HV pwr supply tap for -150V, 50 kHz kaput; made a Lab pwr supply out of rear 7 inches.

[tggzzz]

If the IC is faulty, see www.ebay.com/itm/Tektronix-155-0091-00-Hybrid-IC-400-Series-Oscilloscopes-GOOD-/141983338495