And U800 is especially fun since it has +87V coming into it (pin 7), which is not shown on the A1 schematic. It's worth looking at the power distribution schematic to know where this and other power pins lie in wait.
Uggghhh, yes why did Tek, in such a detailed service manual, not include any meaningful voltage readings in the schematics of at at least some of the more important nodes or power to IC pins??!!
I imagine any of the former Tek guys will always have a good answer/excuse for this. For me a service manual should have absolutely -everything- I might need to troubleshoot the equipment, and it should rather have too much than too little information. Then again, by looking at some of the horrible mistakes (mixed up power supply caps in wrong positions and polarity, etc) and wonder if these manuals where just rushed out to rather concentrate on equipment sales, and not that much on after sales service literature. Maybe nobody was assigned to proof read them.
Then again, I've seen some pretty obvious mistakes in the Motorola radio equipment service manuals. You would think that a huge company like them that makes absolutely top quality equipment would not make any/much mistakes of this sort, but I've seen it happen quite often. Makes you wonder how these mistakes still managed to slip through. Then again, those manuals where/are usually at least an inch (or more) thick.
Absolutely best service manuals I have ever come across, and so detailed and brimming with information to the level that virtually nothing was left out, where the service manuals for all the Kenwood ham radio equipment from the 80s I used to work on back then. You really got spoiled with those manuals. But I digress....