Hello all! I'm a maker who enjoys fixing stuff... mechanical, electronic, just about anything! I'm hoping to get some info here to help a friend get an older Alesis QS8 up and running. Look forward to 'meeting' you all!
Good Day!
- Thread starter styxfan.wi
- Start date
happyrat1
Destroyer of Eardrums!!!
Could you describe the exact nature of the problem and any steps, if taken, so far to "remedy" it? 
If you own a 3D printer that could end up being handy
Anyway, nice to meet ya.
Gary
If you own a 3D printer that could end up being handy
Anyway, nice to meet ya.
Gary
Hey Gary.... the synth was handed off to me with a display not working. That was a simple fix. Now it seems like the power transformer is not outputting the correct voltage. I'm going to have to dig out the oscilloscope to figure out where the issue is. If indeed it is the transformer, I was hoping that someone on here might know of the equivalent as its an odd one.Could you describe the exact nature of the problem and any steps, if taken, so far to "remedy" it?
If you own a 3D printer that could end up being handy
Anyway, nice to meet ya.
Gary
As an aside, I do have a 3d printer, a k40 laser cutter, and a small milling machine. I'm also building a small lathe. I just like making stuff, lol.
Thanks for the reply!
happyrat1
Destroyer of Eardrums!!!
That's a 20 year old synth you have there.
Before you start ripping out the transformer check the Electrolytics with an ESR meter and see if any are dead or leaking.
If the transformer actually is the culprit there are always transformer rewinding services out there that could bring it back to life.
Does that thing have a switching supply or a conventional bridge supply?
Either way, a simple hack would be to rip out the entire supply if possible and replace it with something modern off the shelf that outputs the correct voltages and currents.
Kewl beans about your maker shop. You sound really well equipped. Unfortunately I have no room for a full workshop in a two bedroom apartment with one devoted already to a home music studio.
I doubt my landlord would be happy if I started machining my own parts anyway
Gary
Before you start ripping out the transformer check the Electrolytics with an ESR meter and see if any are dead or leaking.
If the transformer actually is the culprit there are always transformer rewinding services out there that could bring it back to life.
Does that thing have a switching supply or a conventional bridge supply?
Either way, a simple hack would be to rip out the entire supply if possible and replace it with something modern off the shelf that outputs the correct voltages and currents.
Kewl beans about your maker shop. You sound really well equipped. Unfortunately I have no room for a full workshop in a two bedroom apartment with one devoted already to a home music studio.
I doubt my landlord would be happy if I started machining my own parts anyway
Gary
Welcome to the forums ! Don
Good morning Gary!That's a 20 year old synth you have there.
Before you start ripping out the transformer check the Electrolytics with an ESR meter and see if any are dead or leaking.
If the transformer actually is the culprit there are always transformer rewinding services out there that could bring it back to life.
Does that thing have a switching supply or a conventional bridge supply?
Either way, a simple hack would be to rip out the entire supply if possible and replace it with something modern off the shelf that outputs the correct voltages and currents.
Kewl beans about your maker shop. You sound really well equipped. Unfortunately I have no room for a full workshop in a two bedroom apartment with one devoted already to a home music studio.
I doubt my landlord would be happy if I started machining my own parts anyway
Gary
I am sure your landlord wouldn't be happy if you started throwing chips, lol.
I will be taking a national registry test today, but once that stress is over, I'll be digging into the synth some more.
My 'usual' music maker is an M-Audio Oxygen II controller combined with Reaper DAW and a bunch of VSTs.
I also have a Roland JX-305. A very interesting, and deep machine... I bought it (cheap.. the pawn shop had no idea what they had) for the great bagpipe sound, as 'Copperhead Road' is one of my favorites to do at jam sessions.
I see you have a bunch of synths on your profile pic. What types?
Now that I've written you a book, I've got to head to the College to wait half a day for my test... feels like I'm back in the army... hurry up and wait
happyrat1
Destroyer of Eardrums!!!
The Synths I own are listed at the bottom of my sig. Along with links to my music if you care to give them a listen
Anyway, you omitted the answer to my previous question.
What type of power supply is in there currently? Switching or Standard Regulated? Either way is it installed on the main board or is it a separate module connected by Molex cables?
Easiest thing to do might be to replace the entire supply.
Repairing switching supplies can be dangerous considering the voltages in those.
Gary
Anyway, you omitted the answer to my previous question.
What type of power supply is in there currently? Switching or Standard Regulated? Either way is it installed on the main board or is it a separate module connected by Molex cables?
Easiest thing to do might be to replace the entire supply.
Repairing switching supplies can be dangerous considering the voltages in those.
Gary
I will give a listen to your music, and my apologies for missing the agar to your question. It is a bridge rectified type. The supply board is supposed to output an AC signal at 9v. I need to get it on a scope to check out the waveform.
Looks like you've got some great gear!
Looks like you've got some great gear!
happyrat1
Destroyer of Eardrums!!!
I'm a little confused? Did you mean 9V DC?
If it is 9V AC then remember that's the RMS value, not the Peak to Peak value.
If it's 9V DC then the ripple current should be insignificant on a regulated supply.
And thanks for the compliment on my gear. I've spent (wasted?) half a lifetime on assembling it.
At this point my gear far exceeds my talent.
Gary
If it is 9V AC then remember that's the RMS value, not the Peak to Peak value.
If it's 9V DC then the ripple current should be insignificant on a regulated supply.
And thanks for the compliment on my gear. I've spent (wasted?) half a lifetime on assembling it.
At this point my gear far exceeds my talent.
Gary
It is AC. Yeah, I do realize that it's RMS. That's why I need to scope it out. Now that I've gotten thru the NREMT practical, my mind will get back to normal . It's been really stuffed with too much info.
Keep playing!
Paul Peterson
Keep playing!
Paul Peterson
happyrat1
Destroyer of Eardrums!!!
Could you post a pic of the supply to give us a better idea? AC output is weird. Is it a wall wart or is it a line cord feeding into a module on the keyboard itself?
Gary
Gary
Hey Gary!
I'm digging on your tunes... I wish I had your talent... I'm best at vocals, and can pick out parts with my right hand... I think it would take me a year to lay down anything close to what you've accomplished!
I'll work on getting some photos of the QS power supply after I'm off call. It is enclosed in the case, standard line cord like you would find on any desktop computer. That feeds the power transformer board, then into the main PCB of the synth. It gets rectified, then filtered on the main PCB, then gets split to +5vdc and -5vdc. I'm hoping I have time today to get it on the scope.
Cheers!
Paul
I'm digging on your tunes... I wish I had your talent... I'm best at vocals, and can pick out parts with my right hand... I think it would take me a year to lay down anything close to what you've accomplished!
I'll work on getting some photos of the QS power supply after I'm off call. It is enclosed in the case, standard line cord like you would find on any desktop computer. That feeds the power transformer board, then into the main PCB of the synth. It gets rectified, then filtered on the main PCB, then gets split to +5vdc and -5vdc. I'm hoping I have time today to get it on the scope.
Cheers!
Paul
happyrat1
Destroyer of Eardrums!!!
You're saying they designed the Transformer on a modular board and left the rectification and regulation on the main board? Extremely weird.
Check the specs on power consumption if you can find them, double them, and you should easily be able to find a compatible replacement.
That is IF you have tested the transformer out of circuit. Is it multitapped or just center tapped?
Multitapped might be a little tougher to find, but not really. It's amazing what places like Jameco and Digi-key have in stock.
Personally though, you have to go a long way to convince me the problem is with the xformer and not the regulation circuit loading it. Disconnect the xformer leads and then see if it's outputting specs. If it's driving +/-5V (and maybe +/-12V or +/-15V as well) those are all pretty standard outputs it should be outputting the regulated voltages + about 30% RMS. Load rating should be no more than a couple of amps.
But, as I was getting at, xformers are pretty much static devices that almost NEVER break down unless the operating conditions are brutal.
My first guess is the filter caps, then the semiconductors and LASTLY the xformer.
It could even be a weird fault in the motherboard that's shorting somewhere and sucking all the current.
Since it's such a weird design, separating the power supply from the main board for testing could prove problematic.
Gary
Check the specs on power consumption if you can find them, double them, and you should easily be able to find a compatible replacement.
That is IF you have tested the transformer out of circuit. Is it multitapped or just center tapped?
Multitapped might be a little tougher to find, but not really. It's amazing what places like Jameco and Digi-key have in stock.
Personally though, you have to go a long way to convince me the problem is with the xformer and not the regulation circuit loading it. Disconnect the xformer leads and then see if it's outputting specs. If it's driving +/-5V (and maybe +/-12V or +/-15V as well) those are all pretty standard outputs it should be outputting the regulated voltages + about 30% RMS. Load rating should be no more than a couple of amps.
But, as I was getting at, xformers are pretty much static devices that almost NEVER break down unless the operating conditions are brutal.
My first guess is the filter caps, then the semiconductors and LASTLY the xformer.
It could even be a weird fault in the motherboard that's shorting somewhere and sucking all the current.
Since it's such a weird design, separating the power supply from the main board for testing could prove problematic.
Gary
happyrat1
Destroyer of Eardrums!!!
BTW, thanks for the kind words about my amateur dabblings in music on the web.
With 20 years of hunt and peck eventually even a chimp can learn to hammer out a tune
Recently I've been getting myself up to speed with wxPython and C++ to start writing my own MIDI applications.
I'm getting tired after multiple decades of waiting for stable open source music applications and decided to spend my dementia years playing with computer code as well.
Gary
With 20 years of hunt and peck eventually even a chimp can learn to hammer out a tune
Recently I've been getting myself up to speed with wxPython and C++ to start writing my own MIDI applications.
I'm getting tired after multiple decades of waiting for stable open source music applications and decided to spend my dementia years playing with computer code as well.
Gary
The computer code will keep you sharp!
I've also found some frustration with MIDI over the years... I'm also of the 'hunt and peck' synth playing. I've got decent pipes, and a good sense of rhythm, but fall short making my fingers all work together... maybe I'll get it with enough practice.
Things have been crazy busy at work, multiple runs per day (as opposed to our usual maybe one run)... I'll let you know how I get on with the power issue.
Have a great day!
I've also found some frustration with MIDI over the years... I'm also of the 'hunt and peck' synth playing. I've got decent pipes, and a good sense of rhythm, but fall short making my fingers all work together... maybe I'll get it with enough practice.
Things have been crazy busy at work, multiple runs per day (as opposed to our usual maybe one run)... I'll let you know how I get on with the power issue.
Have a great day!