I have looked in the usual places but have not found a service manual for this specific General Resistance instrument. The company is now Prime technology.
The DAS 45 has more adjust points than the instruments for which I can find schematics. It has three ranges 10 V, 1V and 100 mV.
The schematics for lots of other similar units are available, but I cannot find this specific model.
Thanks in advance Wally