[Premium-Rx] SIEMENS CHR531 HELP REQUESTED

[Clemens Paul]

Hello Pat,

today I've met a fellow-ham on the bands who owns three CHR531.
He was the man I'd been waitng for after your posting. :-)
He wasn't aware of any factory mods regarding the frequeny memory
but suggested to check the memory back up battery (maybe NC),
it should have as far he could remember around 5 or 6 Volts.

HTH
and let us know of the result.

73
Clemens
DL4RAJ

----- Original Message ----- 
From: <Pat1McA at aol.com>
To: <premium-rx at mailman.qth.net>
Sent: Thursday, July 30, 2009 9:53 PM
Subject: [Premium-Rx] SIEMENS CHR531 HELP REQUESTED


> 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
> 
> 
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