From Oakley Sound via analogue Sent Sun, May 26th 2019, 01:07
From Oakley Sound via analogue Sent Sun, May 26th 2019, 01:07
Again, sorry my posts are separate threads.
Even if the battery itself is good, you may want to confirm with a meter
that the battery voltage is making it to pin 18 of the RAM chips when power
is off. The schematic is wrong, in that it shows +5V going to chips 2L
and 2M,
but those chips get +5E as they are battery-backed up. You should see
battery
voltage minus about 0.3-0.5 volts on pin 18 of all 4 chips when power is
off.
When power is on, the voltage should increase to around 5.0 volts
The 5114 is a CMOS RAM chip, unlike something like a 2114 which is NMOS
and would kill the battery very quickly. I do see a few people on ebay
selling
5114-type SRAM chips. ebay is a good place these days for unusual chips,
but you need to be careful to buy from reputable people. Unless you know
what you are doing, I suggest avoiding chips from China as many of them
are not what they seem.
Probably any 5114 RAM would be fast enough to work in the Synthex.
If you are able to record and play back sequences normally once you have
cleared the RAM, then maybe it is some sort of battery issue and not a bad
RAM chip. Really hard to say. If the presets are preserved reliably when
power is off, then probably the battery and related circuits are OK,
although
you could still have an issue with chip 1P that would only affect the
sequencer
RAM and not the presets.
Good luck
Bob Grieb
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