[KL] My MIDIBoard needs help.

Discussion:

laurie.spiegel@gmail.com [KurzList]

2014-11-30 02:05:28 UTC

I had it boxed up for the past dozen years, being into other than keyb for awhile. Unboxed it and set it up, and ... it's not work. :-(

Booted up with "Err 13". I cancelled the error and ran the onboard diagnostics. On the info display test, the switches are all working, including pedals. But the keyboard, control knobs and sliders all give zero response. MIDI loopback and other tests are normal.

Have any of you seen this before? Any chance this (sliders, control knobs and keyb all out, everything else working) might be a single point problem such as an internal fuse or bad contact in one of the cables?

Thanks in advance for any thoughts, hints or ideas. I have the user manual but no service manual.

Daniel Forró danforcz@yahoo.com [KurzList]

2014-11-30 03:10:39 UTC

Permalink

Hi, Laurie,

if the instrument was not used for longer time, leave it on day and
night (but check it from time to time).

Error 13 according to SM is:
A/D converter ground reference out of range

The possible reason and solving this error is described in SM.

I have sent the SM to your address, as I did before to other members
of this group asking the help.

You can also suspect usual problems with oxidized contacts (it depends
on climate, humidity and so) after such long time of sleep. Open the
machine, and disconnect and again connect carefully connectors one by
one, or use some contact cleaning spray.

Also OS Eprom or other IC's in sockets can be carefully reseated.

And you can try to do factory reset (which will erase your settings!):

- turn memory protect off
- press Shift + To Cass simultaneously
- the screen will display "Enter test or Diag #"
- press 0
- the screen will display "Restore?"
- press 1

Daniel Forro

Post by ***@gmail.com [KurzList]
I had it boxed up for the past dozen years, being into other than
keyb for awhile. Unboxed it and set it up, and ... it's not work. :-(
Booted up with "Err 13". I cancelled the error and ran the onboard
diagnostics. On the info display test, the switches are all working,
including pedals. But the keyboard, control knobs and sliders all
give zero response. MIDI loopback and other tests are normal.
Have any of you seen this before? Any chance this (sliders, control
knobs and keyb all out, everything else working) might be a single
point problem such as an internal fuse or bad contact in one of the
cables?
Thanks in advance for any thoughts, hints or ideas. I have the user
manual but no service manual.

Roger J winking_n_nodding@yahoo.com [KurzList]

2014-11-30 03:27:23 UTC

Permalink

All keys, sliders, wheels are analog voltage values that are sent through multiplexers to the ADC or analog to digital converter. There is a clock, a reference voltage, the ADC IC and possibly some of the logic just prior to the ADC.

I have never seem a bad ADC IC. Lots of bad ICs in the logic/multiplexing.

A scope is needed for clocks and multiplexing trouble shooting. 1st point would be the single white wire leaving the logic board going to the key board, 14 to 18 volts pp at 100kHz. Everything is sync'd to that signal. You can look at the stream going to the ADC and see each key, slider and wheel.

Strange that it worked, stored and now does not, this suggests connections issues, reseat plugs and I Cs. But parts can fail in storage too.
Diagnostics are basic, but can help determine what is occurring.

Sent from my ASUS Pad

Post by ***@gmail.com [KurzList]
Â
I had it boxed up for the past dozen years, being into other than keyb for awhile. Unboxed it and set it up, and ... it's not work. :-(
Booted up with "Err 13". I cancelled the error and ran the onboard diagnostics. On the info display test, the switches are all working, including pedals. But the keyboard, control knobs and sliders all give zero response. MIDI loopback and other tests are normal.
Have any of you seen this before? Any chance this (sliders, control knobs and keyb all out, everything else working) might be a single point problem such as an internal fuse or bad contact in one of the cables?
Thanks in advance for any thoughts, hints or ideas. I have the user manual but no service manual.

laurie.spiegel@gmail.com [KurzList]

2014-11-30 05:26:23 UTC

Permalink

Much thanks for these answers! And Daniel, special thanks for the SM+schematics. Too late here (NYC) tonight to try out your suggestions. I hope they will revive it tomorrow.

I know that some chips will fail over the years regardless of use or non-use, e.g. the ADSRs used in some '80s synths. Any chips known to be in the MIDIBoard that have been found to not last?

Yes I do have a dual-trace scope and voltmeter to check it with, but I'm hoping reseating and cleaning the connections will show it I care enough that it will play music together again.

- Laurie

Daniel Forró danforcz@yahoo.com [KurzList]

2014-11-30 06:33:40 UTC

Permalink

Hi, Laurie,

you are welcome.

I'm not so much expert in IC's, being musician with DIY electronics
repairs only as the hobby. Maybe some can die after the shock from
switching on the machine again after so many years of sleep, when
maybe other passive components could deteriorate just by the age
(caps?) even when not used? As far as I know CMOS chips are sensitive
to static electricity when they are not connected in the circuit, but
I didn't checked recently if there are some...

I'm sure Roger will know more about.

Maybe lot of things can be revived just by leaving the machine
switched on for longer time. A technician who repaired my CS80 which
was not used for 20 years left it on four days and nights, and then he
started to repair it.

Good luck with your repair!

Daniel Forro

Post by ***@gmail.com [KurzList]
Much thanks for these answers! And Daniel, special thanks for the SM
+schematics. Too late here (NYC) tonight to try out your
suggestions. I hope they will revive it tomorrow.
I know that some chips will fail over the years regardless of use or
non-use, e.g. the ADSRs used in some '80s synths. Any chips known to
be in the MIDIBoard that have been found to not last?
Yes I do have a dual-trace scope and voltmeter to check it with, but
I'm hoping reseating and cleaning the connections will show it I
care enough that it will play music together again.
- Laurie

laurie.spiegel@gmail.com [KurzList]

2014-11-30 18:04:00 UTC

Permalink

Leaving it on would cause components to heat up and expand, perhaps making contact at point where corrosion was little enough to be rubbed off by that contact. Who knows? Sometimes it seems there is a ghost inside each of our electronic instruments.

I will start by reseating the various connectors, hopefully later today, and maybe that will bring it back.

Anon,

- Laurie

Roger J winking_n_nodding@yahoo.com [KurzList]

2014-11-30 18:05:20 UTC

Permalink

There are CMOS 4000 series components, mainly 4051s and the 2 6500 series. Both series are static damageable, but that is rare.

Electrolytic caps are few, look for leaks, green or black spots on traces near any suspected leakers.

Do you have an early USA built "short logic board" or USA built long logic board(19+ inches)or Japan built long version? Also, the service manual was a work in progress that was never completed. The long logic board featured is from the EG piano and has extra memory chips shown, 4 instead of the 1 used on the long boards in the MIDI Bd. Some version component number to not match schematic.

If the 6502 and 6522 LSIs are in sockets, clean and reseat, tin leads in tin sockets. Many issues occur from sockets of this type. Gold high reliability type (round socket hole and pins) work very well if you need to replace the tin OEM ones.

C50, the ADC zero adjustment should be left alone. If you need to touch it because it does not zero( usually something else is wrong), do it in the display diagnostic using a panel slider to get zero to 255 range. On some versions, the wheels may not range the full zero to 255, not to worry as software trumps here.

Also are you running version 3 or ? All versions were very stable.

Sent from my ASUS Pad

Post by Daniel ForrÃ³ ***@yahoo.com [KurzList]
Â
Hi, Laurie,
you are welcome.
I'm not so much expert in IC's, being musician with DIY electronics repairs only as the hobby. Maybe some can die after the shock from switching on the machine again after so many years of sleep, when maybe other passive components could deteriorate just by the age (caps?) even when not used? As far as I know CMOS chips are sensitive to static electricity when they are not connected in the circuit, but I didn't checked recently if there are some...
I'm sure Roger will know more about.
Maybe lot of things can be revived just by leaving the machine switched on for longer time. A technician who repaired my CS80 which was not used for 20 years left it on four days and nights, and then he started to repair it.
Good luck with your repair!
Daniel Forro
Much thanks for these answers! And Daniel, special thanks for the SM+schematics. Too late here (NYC) tonight to try out your suggestions. I hope they will revive it tomorrow.
I know that some chips will fail over the years regardless of use or non-use, e.g. the ADSRs used in some '80s synths. Any chips known to be in the MIDIBoard that have been found to not last?
Yes I do have a dual-trace scope and voltmeter to check it with, but I'm hoping reseating and cleaning the connections will show it I care enough that it will play music together again.
- Laurie

laurie.spiegel@gmail.com [KurzList]

2014-11-30 19:29:10 UTC

Permalink

Hi Roger.

Yes, running v. 3 software, and the logic board measures 19". Not sure how to tell if it's the US or Japan version. Unlike the one in the photo Daniel emailed me yesterday though, there is a fuse mounted between the 2 smaller of the 3 large capacitors at one end of the board. (Fuse appears to be ok on visual inspection, and there is no version number printed above the large cap in the photo he sent. There appear to be 2 ROMs or ePROMs with typed stick-on labels in 2 of the sockets that are empty in the photo he sent too.

I'll try to send a photo of mine, though it's in an awkward location to photograph.

I bought this keyboard back in the 1980s, and it worked flawlessly and was a great pleasure to play right up until I needed the space for other instruments.

- Laurie

jp.geersing@xs4all.nl [KurzList]

2018-02-03 16:51:42 UTC

Permalink

Hi Laurie,

It was a few years ago already but is your Midiboard working again?

Regards,
JP

laurie@xanadu.net [KurzList]

2018-04-04 05:25:28 UTC

Permalink

Hi JP.

Delayed response but I only just now saw your message here.

No, alas, it is still in the same partiallly-functional state as when I posted. Thanks for remembering and asking!

Laurie