K5synth

What interests me is that your machine works for a bit, then fails for an hour.

There are two possible reasons for this:

	- A component is failing when it warms up, and you must let it cool back down.  I wonder what happens if you leave the machine open, with a fan blowing cold air into it.  Does it stay on slightly longer?

	- You have a very small crack in a solder joint etc. which acts like a capacitor.  It works for a while, but then it builds up enough capacitance to cut off the connection.  You have to then let it sit for a long time to bleed out the capacitance.  This happened to me once with an old NeXTstation, though the bleed-out time was about 10 days.

Either way, this doesn't sound like fun.

Sean

> On May 18, 2019, at 12:38 AM, cball@... [k5synth] <k5synth@yahoogroups.com> wrote:
> 
> Hello thanks for your replies.
> 
> 
> I have purchased a new 1.2 ROM and have it in the unit.  It responds the same way as the 1.0 ROM.
> 
> I have been able to repeat the results: If I turn it off, battery out then on start I can briefly adjust all parameters.  I set it to the master tune, adjusted it up +4 and left it for several minutes, just to see what would happen. 
> 
> The K5 maintained flashing the +4 until I moved the data dial and we are back to limited selection. When in that state, I can rename patches, change patch volume, but I cannot save with or without battery in, with or without memory protect on/off. I also cannot change System parameters.
> 
> Briefly, everything is as expected, then limited control. I was bale to set MIDI channel, then back to no luck.  I have to leave it off for about an hour to get it to briefly allow System changes.
> ! 
> I think perhaps one of the RAM chips is failing or somehow being shut off, this could be as you mentioned a power supply issue. I have schematics from Kawai, there are several RAM chips on both the M-03 and M-04 board, but I think It could be the working RAM.
> 
> I'm also wondering if the RAM is getting written too by the system and filling up.
> 
> It doesn't help that I have an early revision, with jumpers soldered here and there and oddly the ROM in the alternate slot. I purchased another K5m motherboard and it has numerous differences, would not work with the K5 shell I have I think because of the power headers in different locations.
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