Yes, you're right no transistors in this circuitry. (different though in the OB-Xa and OB-X)
I agree with Jacob: after you have checked the CMOS memory chips, check D4, C14, C13, C2, C3, ?and also U14.
I would start with removing each of the CMOS memory chips and then CMOS IC U14 because this IC is also a socketed and thus easy to check. If the high current goes away with a party removed you have identified the faulty part.?
make sure that you can reliably measure the low current flowing from the battery during the procedure. Do not use anything else but a battery to check this. Do not use any other voltage source as a replacement for the battery. Use a battery operated current meter. ?You will otherwise obtain erroneous readings as ?low currents are involved. ?
Good luck
Mondo
Mondovermona