The first time I let it on for a couple of hours, randomly changing patches or moving controls every time I walked by. Plugged it back in, waited three minutes and then…it kept working. I removed all the knobs, removed the two control panel PCBs from the case, and cleaned & lubed all of the pots & switches. Suppose one was dirty? It was conceivable that the CPU could read that as constantly changing, and hang up attempting to deal with it. Once the unit finishes tuning, it has to monitor the status of all the front panel controls, not just the switches but also the rotary pots. In talking to a friend about it at some point in the conversation I was explaining that this unit is microprocessor based…which got me thinking (not as dangerous as it sounds). The consistency of the failure, though, is unusual. In my day job I work with computers so at this point I’m thinking it’s a bad chip. It didn’t appear to be thermal – I got the same few minutes of normal operation whether it had been on for a minute or an hour. The main chips – including the processor – are all socketed, so I popped them all out, checked for bent or mis-aligned pins, and reinstalled everything. I dug up the schematics and checked all the voltages they were all fine.
The symptoms would generally lead me to think it was either a power or thermal issue. Obviously, unless you’re in a band playing REALLY short songs, this rendered it pretty much unusable. If you turned it off and back on, the same thing happened. Then the control panel would lock up and pressing buttons had no effect. The unit powered up correctly, ran through the tuning cycle, and appeared to be perfectly fine – for about three minutes. I told him that if I can locate the service information for the retrofit, he can bring it back.Īnd of course the other positive note is that after this one I’ll never be afraid of doing a Polysix battery repair again.Ĭustomer had a Prophet 600.
#Korg poly 800 facotry reload file Patch#
It doesn’t affect playability at all, or patch selection. In the end, the customer picked up the unit and was extremely happy, even with the quirky issue saving patches. I also verified that not only does the MIDI interface work, but the additional patch storage locations are accessible. I ended up entering the missing patches manually. They’d partially load, but then I’d get an error. Ignoring the odd behavior, I tried reloading the factory patches from known-good WAV files.
At least I was able to disable the external sync for the arpeggiator, so now the whole synth side worked as it should. A web search turned up a user’s manual, but no schematics. Realizing that the retrofit might be causing an issue, I tried to locate documentation. The arpeggiator didn’t work, though, and while I could still store patches the behavior of the programming section seemed odd. This time, the synth section was perfect and it sounded fantastic. A quick dab of solder, a minor change of position, and after I pulled the keyboard and took care of the bad keys it seemed to be working – almost. I found one wire that wasn’t soldered correctly, and also noticed that the metal mount for the retrofit was shorting a couple of resistors. Powered it off, pulled the board, and went over it again. I could create a patch and it would store, but they all sounded horrible. Some of the controls worked and some didn’t. “Oh you need little teeny eyes for reading little teeny print…”ĭouble-checked everything, installed the new components, put everything back together, hit the power, and…success! Sort of. I pulled the ribbon cables, but had to leave everything else connected.Īnd this is why I’ve started wearing my glasses more often. There are also hard-wired (soldered) connections to the front panel controls, the key assigner, and the voice board. Two of the larger CMOS chips that are normally on the programmer are instead installed on the retrofit, with ribbon cables leading back the the original sockets. The first hint came in trying to access the KLM-367 programmer. I also had no idea how difficult it was going to make the repair. I honestly didn’t know that Korg even made an interface for this. It was unusual in that not only did it have MIDI, it had an original Korg MIDI retrofit installed from the factory. This unit was not unusual in that the battery had indeed leaked, and I could immediately see several components were damaged. I’ve done several of these in the past this was by far the most challenging to work on.
A wonderful piece of vintage awesomeness, except for the unfortunate tendency for the on-board battery to self-destruct, taking the programmer board with it.