Roland Alpha Juno 2 won't power on...

[NostalgicSoundsGuy]

Hi everyone, I plugged in and switched the power on, but my Alpha Juno 2 won't turn on. I've noticed the vents on the back feel a little warm. What could this mean?

[NostalgicSoundsGuy]

So I opened it up and didn't find any black burn marks or anything else out of the ordinary. Hmmm...

[Yekuku]

Hi,
it seems that u have a problem in the power supply board.
I dont remember if the PS has a fuse, but check it just in case.
The PS should output -15V,+15V,5V to the mainboard and 90V (?) to the lcd.
Also check for blown capacitors, shorted filter caps & shorted regulator.
Watch out while trying to disassemble, you can damage the main board quite easily.

Now wait a second ! are u sure that the power cable is ok ?

[NostalgicSoundsGuy]

Thanks for the reply!

Okay, it powers back on, but only when I shake it. If I move it slightly again, it powers off. I also used another compatible power plug. So the power supply or fuse needs to be replaced?

[rhino]

Never had that model - does it have a power cord with a little transformer on the end that goes into the wall? If so, chances are someone has bunged the power plug and damaged the socket on the back of the synth. If that's it, no need to replace the entire power supply (inside the synth).

[garranimal]

If I recall the power cord is that Roland two-prong bastard. So either the cord has a loose connection at the synth or perhaps something on the power supply board has an intermittent connection that needs re-soldered.

[Yekuku]

The juno's power cable is quite rare, I am surprised how easily you have found a compatible one to test it.
Does it look like this ?

Could it be that the power supply was modded to accept a 3-wire power cable? This is a common mod to roland synths of that era.
Anyways as garranimal said, it is possible that some contact inside the power supply got loose or broken and needs re soldering.

[garranimal]

The juno's power cable is quite rare, I am surprised how easily you have found a compatible one to test it.
Does it look like this ?

Could it be that the power supply was modded to accept a 3-wire power cable? This is a common mod to roland synths of that era.
Anyways as garranimal said, it is possible that some contact inside the power supply got loose or broken and needs re soldering.

New two-prong cords can be found on ebay. Korg DW-8000 used that same thing, too. Sometimes the aftermarket versions of the cord need to be shaved down a hair to go all the way in the jack.

[Yekuku]

The easiest way to find one is to search for IEC C9 cable

[rhino]

OK, I blew this one. Sorry.
Another thing I find in older synths is a broken connection at the power switch. Opening and closing the case for repairs can strain the wires.

Also, last I heard HOSA still made the two-pin cords.

[NostalgicSoundsGuy]

I used the original 2 prong power cord and a compatible HOSA brand (easy to find in Amazon.com and ebay). Okay, so I opened it up again for a second look and I still don't see anything wrong with this unit. All the PCB boards, wiring and connections look fine. I turned it on and it powers on, but I've noticed the lcd screen not showing anything (though the LCD backlight screen is on). More trouble?

[rhino]

Well, let's try something else.
WITH THE SYNTH UNPLUGGED - check all connectors. unplug and re-plug all of them. Then try the power again.

WARNING !!!! IF YOU DIE, DON'T SUE ME !!!!!!!

With the power ON, poke and prod things GENTLY WITH A NON-CONDUCTIVE STICK. I use the handle cut off of a long plastic mixing spoon. Press gently on all socketed ICs


If you're not confortable doing this, THEN DON'T !!!!!!!

Ribbon cables and their connectors are always suspect.
Keep us informed

[Yekuku]

I got confused, please make some things clear.
(1)As you said at the start of the thread, the synth did not power on but it was getting warm.(As I understand the lcd did not light up, synth appeared dead)
(2)Then when you shook it the synth worked ok until it was shaken again. (The synth was working ok for a few moments)
(3)Now the synth powers on ( without shaking) but only the lcd lights up.

The cause of problem (2) is in the power supply. Probably sth is not connected properly or got loose.By using a multimeter and checking for continuity (synth powered off) , it is possible to find the broken connection.

The cause of problem (3) could be in the power supply or in the mainboard that is located under the keybed.
Could it be that you tried to remove the keybed and damaged the mainboard ?
In order to find where is the problem you have to check this :

The PS should output -15V,+15V,5V to the mainboard

You can check this by using a multimeter and measuring voltage (dc) on the connector labelled CN3 of the power supply unit.(synth powered on)
If you dont read 15V,+15V,5V you have a problem in your power supply , if you do then you have a problem in your mainboard.
If you dont feel comfortable with what I am saying then take the synth to someone with more experience in electronics.
Also do what Rhino is telling you, sometimes a loose connection is the most common suspect.

[NostalgicSoundsGuy]

Thanks for all the helpful replies everyone! I'll just take it to a repair shop, since the only thing I'm only good at is cleaning the keys and the unit. I'll go ahead and mark this thread as "solved". I greatly appreciate all the help!

[Ricoche]

Hello!

This is an old thread, but I'm curious about what the problem was with your Juno 2. Was a part replaced? Was something loose and needed soldering? Did something die out? I'm seeing more Juno 2's with power no issues. I'm reluctant to buy without some sort of idea about other's past experiences. Thanks!