Happy New year y'all! I attempt to repair one of two HP 8116A pulse generators that I got off eBay for cheap.

0:00 – Overview
5:14 – Visual inspection
9:30 – Source of horrific sound determined! (loud fan)
11:00 – cracked R1 resistor on E53 unit
11:38 – Review of error codes E31 & E53
13:24 – Checking main outputs of both units
16:55 – Placing E53 unit in Servicing Position
18:16 – Testing Power rails for accuracy
20:33 – Removal of cooling fan for repair
23:44 – Fan reinstalled and R1 replaced
26:53 – Test power rails for ripple with scope
32:09 – Review of HP ASICs
34:18 – Start of Chpt 10.3 VCO & Width troubleshooting
35:49 – Issue with U150 Control Mode Truth Table
38:10 – Start of Chpt 10.4 Shaper IC troubleshooting
40:07 – Checking Shaper IC U401 inputs (pins 18 & 19)
43:32 – Checking Shaper IC U401 fast-mode input (pin 12)
47:14 – Swapping VCO (Slope) IC U201
48:34- Conclusion of repair