[Premium-Rx] SIEMENS CHR531 HELP REQUESTED

[Pat1McA at aol.com]

Greetings to all,
 
I am working on a CHR531  receiver which will not store the displayed  
frequency in any of the 12 memories. 
 
It appears that the Frequenzspeicher, (S42045-E723-A1-*-7411) Frequency  
Memory, MM74C89 Memory ICs are not being addressed correctly on the Write 
(STO)  cycle..
 
The incoming Memory Address from the Front Unit is correct but IC  581 
appears to not be getting the required Logic High ? (on pins  9,2,6 &13)  to 
allow this to be transferred across to the Memory  ICs.
 
Something is wrong around ICs 567, 556 & 568. Needless to say I have  
changed these out - still the same.
 
I can't help thinking that there may be a factory mod for this problem as  
it must have worked OK at some time! My circuit info is  dated     04 
433/3586 10.03.83
 
Has anyone else come across this or are you aware of any  modification or 
circuit update please????????
 
This is completely driving me to drink - not too difficult these  days.
 
Thanks in advance,
 
Pat G3YFK