Search found 22 matches

by SQLGuy
Mon Apr 20, 2015 3:03 pm
Forum: HELP!
Topic: Roland R-70 low output from right main channel?
Replies: 1
Views: 996

Re: Roland R-70 low output from right main channel?

If the headphones and main outs use different volume controls, then it could be a dirty (or cracked) volume slider. Could also be cracked connections where the jack is soldered to the board. Both of these situations would likely mean that moving the slider, or the jack, around make the problem come ...
by SQLGuy
Mon Apr 20, 2015 2:55 pm
Forum: HELP!
Topic: Korg DW6000 Power Problem
Replies: 11
Views: 6573

Re: Korg DW6000 Power Problem

No. Measure them in circuit. You're trying to find out whether one of the circuits they feed has a short on it.

If the regulator itself was shorted, that would be low resistance from input to ground.
by SQLGuy
Sun Apr 19, 2015 7:51 pm
Forum: HELP!
Topic: Yamaha DX-100 - Help me fix mine!
Replies: 4
Views: 1079

Re: Yamaha DX-100 - Help me fix mine!

MCM Electronics is a good source for reasonably priced repair and diagnostic tools. The jack is probably broken at the circuit board. If you're lucky, it may only need to be resoldered. If you're not, you may need to repair the board with epoxy and jumper wires over broken traces, and/or install a n...
by SQLGuy
Sun Apr 19, 2015 7:46 pm
Forum: HELP!
Topic: Korg DW6000 Power Problem
Replies: 11
Views: 6573

Re: Korg DW6000 Power Problem

7805 is a +5 volt regulator. 7905 is a -5V regulator.

IIRC, 7805 is, from left to right, Input, Ground, Output. You should probably be measuring at least 5 Ohms between ground and output. If it's less, then something on that branch of the circuit is shorted.

Pictures would help, too.
by SQLGuy
Fri Mar 06, 2015 5:53 am
Forum: HELP!
Topic: MU128 piano behavior, normal?
Replies: 1
Views: 1120

Re: MU128 piano behavior, normal?

Here's the rest of the story: First I contacted Yamaha, who basically said, it's old, they don't have one, and to try a different controller. I tried a different controller... no difference. I also asked if there were any firmware updates, but they didn't answer that question. In searching around my...
by SQLGuy
Mon Mar 02, 2015 8:45 pm
Forum: HELP!
Topic: Help - What is wrong with this key? (I think a simple issue)
Replies: 4
Views: 1380

Re: Help - What is wrong with this key? (I think a simple is

My guess would be that it's been hit badly in the past and part of the plastic tab at the back of the key that hinges it to the keyboard chassis is chipped or cracked. Probably the key in question needs to be replaced.
by SQLGuy
Sun Mar 01, 2015 10:13 pm
Forum: HELP!
Topic: Any idea what the sample rate is for the K1 wave ROM?
Replies: 2
Views: 1090

Any idea what the sample rate is for the K1 wave ROM?

I pulled the wave ROM from my K1m and read it. Now I'm trying to listen to it (out of curiosity, and maybe with an eye towards trying some alternate samples at some point).

I know it's 8-bit PCM, but I have no idea of the sample rate. Anyone know?
by SQLGuy
Fri Feb 27, 2015 6:39 pm
Forum: HELP!
Topic: Kawai K1 II problem
Replies: 20
Views: 7327

Re: Kawai K1 II problem

Well, the KTG-001 is still available, but it's $88. Not really worth it to repair the K1m, I think.
by SQLGuy
Fri Feb 27, 2015 6:27 am
Forum: HELP!
Topic: Kawai K1 II problem
Replies: 20
Views: 7327

Re: Kawai K1 II problem

So, here's the result: I got the "for parts" K1m and verified that it worked, except for a broken joystick. I got a ROM burner and some new ROMs. I got a copy of the latest firmware for the K1 II and updated to that (v1.3). It made no difference, but I didn't expect it to... just wanted to have the ...
by SQLGuy
Wed Feb 25, 2015 6:45 pm
Forum: HELP!
Topic: how to read circuit diagram for dr-110 midi mod
Replies: 1
Views: 893

Re: how to read circuit diagram for dr-110 midi mod

MIDI runs +/- voltages for bits, rather than +5 and 0 like TTL circuits. The 1K resistors in this circuit are acting as a simple way of converting +/- 5V (or more) to TTL voltages that this microcontroller would expect. I think a better approach would be to use a line receiver, like a 1488, but if t...
by SQLGuy
Mon Feb 23, 2015 11:15 pm
Forum: HELP!
Topic: Power supply conversion from 100V to 230V.
Replies: 13
Views: 2894

Re: Power supply conversion from 100V to 230V.

When we lived in Belgium, our apartment building used two-phase 230V, so, as mentioned earlier in this thread by others, both lines were "hot" relative to ground. Not all buildings were wired this way. Some (mostly newer ones) used a 230V hot + neutral, rather than two-phase phase hot. In any case, ...
by SQLGuy
Sun Feb 22, 2015 9:48 pm
Forum: HELP!
Topic: MU128 piano behavior, normal?
Replies: 1
Views: 1120

MU128 piano behavior, normal?

I recently bought a used Yamaha Mu128. I'm using it with a DX-11 as the controller. It sounds good, but I noticed some strange behavior from the lower notes of piano patches. When I play a low key (in the lowest two octaves or so of the keyboard), the first strike is somewhat muffled or muted compar...
by SQLGuy
Tue Feb 17, 2015 6:51 pm
Forum: HELP!
Topic: Kawai K1 II problem
Replies: 20
Views: 7327

Re: Kawai K1 II problem

I did get to speak with one of the guys at Kawai today. He gave me some additional troubleshooting tips and mentioned that, in his experience, it was KTG-003 (the IC that reads the wave ROM) that more commonly causes 1-in-8 keystroke type problems. He had seen this from KTG-002 as well, though. KTG-...
by SQLGuy
Mon Feb 16, 2015 6:14 pm
Forum: HELP!
Topic: Kawai K1 II problem
Replies: 20
Views: 7327

Re: Kawai K1 II problem

I bought a "for parts" K1M. That should be using most of the same components, other than the effects chips, as the K1 II. Waiting to receive it. Worst case, the K1 II still has pretty nice action as a controller.
by SQLGuy
Fri Feb 13, 2015 7:16 pm
Forum: HELP!
Topic: Kawai K1 II problem
Replies: 20
Views: 7327

Re: Kawai K1 II problem

As for "non-proprietary stuff", there's not much of that in the K1 series. The NEC CPU is (I think) off-the-shelf, as is the DAC, the RAM, and a couple of TTL ICs. The rest is four surface mount Kawai ASICs (including the afore-mentioned KTG-002), and two custom mask ROMs. I've been trying to reach ...