Discussion about the Korg PolySix synthesizer

Hi,

Sounds like progress to me. I tried to get you a typical current reading for
the SRAM but couldn¹t measure anything. I then took a look at the data sheet
and found that the device draw 20uA max! A bit smaller than my DMM can read!
So under normal circumstances the having the SRAM in circuit should draw
very little from the battery indeed. This is why a lithium cell should last
well over 5 years in this application. If upon connecting Vdd of the chip
the battery starts to run down then perhaps there could well be a problem.
What is the exact SRAM in use you have there? It should be a Toshiba
TC5514APL-3 which is a 1024 word x 4 bit device. Perhaps you are using an
incorrect part with a higher current consumption. However, I doubt it, I was
be more inclined to a faulty device. Do let us all know!

Cheers,
Andy





On 28/12/2009 15:13, "r_j_d_2.phila" <r_j_d_2.phila@yahoo.com> wrote:

>  
>  
>  
>    
> 
> ok, so i have new data: after removing the SRAM chip and leaving the machine
> off overnight, the battery RESTORED itself to about 2.8V! im assuming that's
> good.
> 
> for the record, my RAM chip, IC32, had been damaged, so i had replaced it with
> a socket. i have popped the 367 board, and verified every trace on IC32, and
> also inspected it for any traces bridging. it all tests 100%. i bought a
> replacement IC, but it might have been a pull.
> 
> so, 2 questions:
> 1-could my RAM chip be pulling the battery down, but functioning correctly
> otherwise? the machine writes/saves/functions properly in the programming
> regard.
> 
> 2-if so, does anyone have a lead on a good replacement chip? thanks-rj
> 
> --- In PolySix@yahoogroups.com <mailto:PolySix%40yahoogroups.com> , Andrew
> Jury <andy@...> wrote:
>> >
>> > ...and a Merry Xmas to you and everyone else in the group! If you don¹t
>> Œdo¹
>> > Xmas then at least I hope you are enjoying a nice break...
>> > 
>> > The battery is there to keep the supply running to the memory subsystem
>> when
>> > the mains power is off, right! This means that pin 18 of IC32 and pin 14 of
>> > IC25 are presented with the battery supply. If you are using a non
>> > chargeable cell and you replaced R91 with a 1N4148 signal diode then make
>> > sure it is polarized correctly. That is with cathode (line) facing towards
>> > the cathode of D15. This allows the battery to supply the two ICs in
>> > question whilst the supply is off but keeps it isolated (diode is reverse
>> > polarized) when on.
>> > 
>> > You should also remove C40 which is now redundant. If you haven¹t done so
>> > then this could possibly be the cause of the problem, if the component is
>> > dried up and no longer working as originally intended. Also check C36 to
>> > verify it is not causing a problem in circuit. You are also quite safe to
>> > remove this and power the circuit on whilst testing. Finally, lift pins 18
>> > and 14 as described again and see if that makes any difference to the load
>> > on the battery.
>> > 
>> > If you are using a 3v lithium cell, such as a CR2032 then you should have
>> > about 3.1v offload and about 2.9-3.0v on load. The figures you sent us do
>> > not describe a circuit which is working properly. Get soldering and let us
>> > know what you find...
>> > 
>> > Cheers,
>> > Andy
>> > 
>> > 
>> > On 26/12/2009 20:50, "r_j_d_2.phila" <r_j_d_2.phila@...> wrote:
>> > 
>>> > >  
>>> > >  
>>> > >  
>>> > >    
>>> > > 
>>> > > greetings, all-happy holidays. got a P6 battery question, to follow up
>>> on my
>>> > > draining battery issue:
>>> > > 
>>> > > i've taken the 367 board out, and cleaned/checked all of the traces
>>> around the
>>> > > battery area. i didnt see any resistance at a low reading level that
>>> looked
>>> > > abnormal. i installed a battery clip socket. now, here are my battery
>>> readings
>>> > > for a brand-new battery:
>>> > > 
>>> > > -OUT OF MACHINE=2.7V
>>> > > -IN MACHINE, MACHINE OFF=1.5V
>>> > > -IN MACHINE, MACHINE ON=2.4V
>>> > > 
>>> > > does this look normal? i probably wont know for another day or two if it
>>> > > drains, but wanted your feedback on if these readings sound normal.
>>> thanks, rj
>>> > > 
>>> > >  
>>> > >    
>>> > > 
>>> > > 
>> > 
>> > 
>> > 
>> > [Non-text portions of this message have been removed]
>> >
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