----- Original Message -----
From: Christian Brunschen
To: Ensoniq-VFX-SD@yahoogroups.com
Sent: Sunday, June 17, 2012 2:51 PM
Subject: Re: [Ensoniq-VFX-SD] SD-1/32 forgets sequencer &c, though battery seems OK
On 17 Jun 2012, at 14:42, jammie wrote:
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
I was checking the voltage from the battery, via the diode and on the actual RAM Vcc pin while the keyboard was switched off: Battery was providing just over 3V, diode voltage drop was about 0.04V, power at the RAM Vcc pins was just about 3V, matching battery_voltage - diode_power_drop.
While switched on, the RAM chip Vcc pin was receiving about 5V, as one would expect when power is on.
I haven't investigated the 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
I replaced the old battery with a battery holder + fresh battery today; so there was certainly a time when there was no battery or similar installed, and the motherboard out of its case, and no power whatsoever to the RAM chips. I've also done a system reset (Preset + top-left soft button).
I did, in fact, also note that on one or two occasions, the memory contents has survived a power-down-and-up, but on most occasions it does not. Perhaps there is some transient power-related issue that leaves the RAM with insufficient power when the power supply is being switched off or on? Hmmm.
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
Yes; I may be able to borrow a scope, to watch the power supplied to the RAM chips, if nothing else ...
With some luck, I may have a spare power supply board that I can try - if that fixes it, it was most likely the power supply; if it doesn't, that would suggest the mainboard is at fault.
You're in the UK, I believe?
Best wishes,
// Christian
----- 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
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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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