Search found 1446 matches

by Mooger5
Sun Mar 17, 2019 9:01 pm
Forum: HELP!
Topic: Alesis QS6.1 battery replacement **Solved**
Replies: 5
Views: 2942

Re: Alesis QS6.1 battery replacement

With so much information available on-line, replacing a dead battery and restoring to factory defaults is like changing a flat tyre. The Service Manual gives good instructions on how to disassemble and reassemble the synth. And here https://www.cyborgstudio.com/wimpy/synthmp3s/alesis/qs61/manual/qs6...
by Mooger5
Sun Mar 17, 2019 8:18 pm
Forum: HELP!
Topic: Korg M1 buttons not working
Replies: 37
Views: 9687

Re: Korg M1 buttons not working

Stop that, it´s not a big deal, and all for the sake of Truth.
You got great communication skills. You should write a sticky Primary on synth troubleshooting. Really!
by Mooger5
Sun Mar 17, 2019 8:09 pm
Forum: HELP!
Topic: Korg Poly-800 not working
Replies: 37
Views: 9037

Re: Korg Poly-800 not working

On the Parts List, KLM896 DTA1 and KLM598 DTA1 and DTA2 are all identical: DTA-114N. DTA114E seems easier to find. The numbers are what matter most. The sufix usually refers to current or voltage rating, etc. Nothing to worry about IMHO.
by Mooger5
Sun Mar 17, 2019 7:46 pm
Forum: HELP!
Topic: Korg M1 buttons not working
Replies: 37
Views: 9687

Re: Korg M1 buttons not working

Image
by Mooger5
Sun Mar 17, 2019 7:40 pm
Forum: HELP!
Topic: Korg M1 buttons not working
Replies: 37
Views: 9687

Re: Korg M1 buttons not working

mikepctvman wrote:Image
by Mooger5
Sun Mar 17, 2019 7:35 pm
Forum: HELP!
Topic: Korg M1 buttons not working
Replies: 37
Views: 9687

Re: Korg M1 buttons not working

Rasputin wrote:In your case, the buttons which failed are designated on the panel board as SW15, SW16, SW17, SW18, SW19, SW20.
Pretty sure it´s sw9, 10, 11, 12, 13, 14 - pin 3 of cn4 - y2 line - pin 13 of the chip. According to the photo provided by the OP, it´s the buttons that are closer to the connector.
by Mooger5
Sat Mar 16, 2019 10:17 pm
Forum: HELP!
Topic: Korg Poly-800 not working
Replies: 37
Views: 9037

Re: Korg Poly-800 not working

The adress chip is IC29. TC40H138. The original parts are sold on Ebay for more than 10 Euros. Modern CMOS equivalents 74HCT138 consume less power and work just as well. And they´re about 50 cents.
by Mooger5
Sat Mar 16, 2019 2:25 pm
Forum: HELP!
Topic: Korg Poly-800 not working
Replies: 37
Views: 9037

Re: Korg Poly-800 not working

Right, any *dashed* control line means it's active when low. So, /wr and /rd are actually active. While /cs and /ce short for chip select and chip enable being high means they're inactive. In other words theyre disabling the chips. The rom and the 81c55 are ignoring incoming data and not outputting ...
by Mooger5
Fri Mar 15, 2019 11:49 am
Forum: HELP!
Topic: Korg Poly-800 not working
Replies: 37
Views: 9037

Re: Korg Poly-800 not working

Not upset. It was sort of tongue in cheek. You did write *removed d1 and r1* in your second last post. I get you meant absent or *removed by designer* and I read that as *removed by user*... Anyway you're probably on the right track. There is a third group of output ports on that 81c55 that controls...
by Mooger5
Fri Mar 15, 2019 12:24 am
Forum: HELP!
Topic: Roland TR-707 Germanium Diode Replacement
Replies: 5
Views: 1881

Re: Roland TR-707 Germanium Diode Replacement

I think the 1N34as I matched for a ring modulator were fakes. They were probably Schottky diodes. Now, being pragmatic, if there is no further information on the required component, I´d say differences between germanium diodes are not critical and any one should fit. I forgot about the exponential r...
by Mooger5
Thu Mar 14, 2019 11:57 pm
Forum: HELP!
Topic: Korg Poly-800 not working
Replies: 37
Views: 9037

Re: Korg Poly-800 not working

Well you could have told us you had a working modded board earlier. That would have saved some time. If a modification works, it´s much more efficient to learn why it works, rather than why it wouldn´t, believe me.
by Mooger5
Thu Mar 14, 2019 1:16 am
Forum: HELP!
Topic: Korg Poly-800 not working
Replies: 37
Views: 9037

Re: Korg Poly-800 not working

crafter I´ll read your post tomorrow..
by Mooger5
Thu Mar 14, 2019 1:15 am
Forum: HELP!
Topic: Korg Poly-800 not working
Replies: 37
Views: 9037

Re: Korg Poly-800 not working

Yes, although now I think it becomes clear in the service manual they´re referring to the six cells as the only power source available, like in a worst case scenario. I had thought the main +5V power bus (A) was dependent on D1 which is a zener. Together with the resistor the diode is only there to ...
by Mooger5
Wed Mar 13, 2019 7:32 pm
Forum: HELP!
Topic: Korg Poly-800 not working
Replies: 37
Views: 9037

Re: Korg Poly-800 not working

Yes, the shield should be grounded to drain away most of the RF/EM interference it picks up. I checked the schematics. Removing those two components does isolate the RAM from the six battery cells. Also the mkII doesn´t have them components. But the first revision of the mkI seemed to need the bat c...
by Mooger5
Mon Mar 11, 2019 11:13 pm
Forum: HELP!
Topic: Korg M1 buttons not working
Replies: 37
Views: 9687

Re: Korg M1 buttons not working

Forgot to tell, to test for continuity the unit must be turned off. Select the beeper in the DMM and probe away. If it beeps, there´s continuity between the traces or the wires.