Patches and discussion for Ensoniq VFX family

the battery should not be charged thats what the diode is for

the battery circuit only comes into play when switched off as the 

ram circuits are feed by the psu and the battery circuit is feed into the same 3v circuit via the diode so no reverse voltage goes to the battery and theres a cap which is charged so that the 3v is constant

when switched off the battery with its 3v charge goes through the diode and carries on charging the cap so thatthe ram chips hold the memory contents

are you cheaking the voltage when switched of are you getting the corect voltage at the diode input and output and are you getting the correct voltage from the charging capacitor

have you done a full hardware reset as the ram chips might have curupted data and are holding the data some times nown as ghost data

preventing good data from being written

this is the second time inrecent weeks that i have heard a sd/32 do this

not from any of the other models could be the sd32 mainboard thats at fualt but you need a logic anilyser and scope for this  
  ----- Original Message ----- 
  From: Tal Rodriguez 
  To: Ensoniq-VFX-SD@yahoogroups.com 
  Sent: Sunday, June 17, 2012 1:35 PM
  Subject: Re: [Ensoniq-VFX-SD] SD-1/32 forgets sequencer &c, though battery seems OK


    

  Hi Christian,


  No help here except to advise to email the guy in California and see if he has a solution. If the battery is being charged then I wouldn't suspect the power supply (initially). I hope this clears up for you soon.

  Tal Rodriguez



----------------------------------------------------------------------------
    From: Christian Brunschen <cb@...>
    To: Ensoniq-VFX-SD@yahoogroups.com 
    Sent: Sunday, June 17, 2012 7:21 AM
    Subject: Re: [Ensoniq-VFX-SD] SD-1/32 forgets sequencer &c, though battery seems OK


    Hmm. Brief perusal of the service manual, page 23, chapter TEST PROCEDURE, section 11. "Disk Change Test/Battery Backup Test (SD-1/VFX-SD Only)", suggests that "Failure indicates a main board problem or a power supply problem." - which does not really narrow things down very much alas. 

    Again, any thoughts, suggestions, etc, would be hugely appreciated.

    // Christian


    On 17 Jun 2012, at 10:46, Christian Brunschen wrote:

    > I have a strange problem with my SD-1/32.
    > 
    > I bought it used on eBay a couple of years ago; when I received it, it still had sequences and such in memory, showing that the battery was fine. Indeed, the analog tests (Preset + Compare) showed the same thing.
    > 
    > Then, a few months ago, when I started it and tried to look at the sequences in memory it told me 'The Sequencer must be Loaded' – in other words, it had completely forgotten the contents of its battery-backed memory. However, it was not complaining about a low voltage level from the battery.
    > 
    > So I figured it might be that the battery was coming loose when the keyboard was cooling off, or something similar. Anyway, I just today replaced the battery with a battery holder and a fresh battery; and the same thing still happens: battery level us shown as '142' on the analog checks page, there's no low-battery-voltage warning, everything seems to work while the keyboard is mains-powered ... but once it's powered off, the sequencer OS and the internal-RAM sounds are forgotten.
    > 
    > I've also checked - while the keyboard was off - the battery voltage (3.04V), the voltage drop across the diode to the right of the battery (0.04V) and the voltage at the power supply pin of the SRAM chips just below the battery (2.99 - 3.00V) – all of which appears to indicate that power is being supplied, and correctly, and as expected.
    > 
    > Had this been a VFX-SD or SD-1 where I had replaced the SRAM chips, those would have been my next suspicion - but on the SD-1/32, these are soldered in place, so there's no potential issue with sockets or similar.
    > 
    > So I am a bit .... lost. This isn't a crippling problem - after all, I can save-and-reload everything - but that's not really ideal and uses the floppy drive a lot. Any suggestions, thoughts, advice would be greatly appreciated.
    > 
    > Best wishes,
    > 
    > // Christian Brunschen
    > 
    > 
    > 
    > 
    > 
    > ------------------------------------
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