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The cult of Roland JD-990
Old 25th May 2021 | Show parent
  #481
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Jesse Skeens's Avatar
 
🎧 15 years
Quote:
Originally Posted by gear_up ➡️
Hi friends, I recently set my 990 up again in my new room after a hiatus and noticed that it is producing some constant hum. It sounds like ground loop hum but I cannot be sure.

Disconnecting the audio cables and MIDI cables has no effect. It's only when I power off my 990 that the hum disappears.

No other devices plugged into the same outlet produce hum, even my XP-30, which also has a 2 prong power cord (all other devices are either using 3 prong or external power supplies).
Hum through an audio connection or is it physically humming? If the latter sounds like a transformer.
Old 26th May 2021 | Show parent
  #482
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by Jesse Skeens ➡️
Hum through an audio connection or is it physically humming? If the latter sounds like a transformer.
Physically humming. There is no noise or hum over audio. Over audio, the noise floor is around -85db through my converter (Orion 32 Plus Gen 3), which is about the same it's always been.

Same kind of hum my H3000 makes, only a bit softer.

Should I stop using it and send it in for repair? Or is it OK to use?

I don't recall my 990 ever humming in my old room however my new room is about 25db quieter than my old room, so it's possible I just never heard it.

Last edited by gear_up; 26th May 2021 at 04:37 AM..
Old 26th May 2021 | Show parent
  #483
Lives for gear
 
usedtohaveajuno's Avatar
 
🎧 5 years
It shouldn’t hum - get it fixed. Sounds like the power supply, that shouldn’t be expensive
Old 26th May 2021 | Show parent
  #484
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Jesse Skeens's Avatar
 
🎧 15 years
Quote:
Originally Posted by gear_up ➡️
Physically humming. There is no noise or hum over audio. Over audio, the noise floor is around -85db through my converter (Orion 32 Plus Gen 3), which is about the same it's always been.

Same kind of hum my H3000 makes, only a bit softer.

Should I stop using it and send it in for repair? Or is it OK to use?

I don't recall my 990 ever humming in my old room however my new room is about 25db quieter than my old room, so it's possible I just never heard it.
Probably fine. I have a H3000 that hums really loudly and been using for years. Lot of older gear does that. As far as I know there's no harm in it.
Old 26th May 2021 | Show parent
  #485
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Monkey Man's Avatar
 
🎧 5 years
Yeah, I had several MOTU interfaces back in the day that hummed so loudly you could hear them from the door of the room 5 metres away.

There was a fix IIRC that involved wedging a piece of cardboard between the transformer and the chassis.

Didn't affect performance in any measurable or perceivable way of course.
Old 26th May 2021 | Show parent
  #486
Gear Addict
It could be the display going on its way out (backlight)...
Old 26th May 2021 | Show parent
  #487
Lives for gear
 
Jesse Skeens's Avatar
 
🎧 15 years
Quote:
Originally Posted by asdfgh ➡️
It could be the display going on its way out (backlight)...
Wouldn't that be a high pitched whine?
Old 26th May 2021 | Show parent
  #488
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Rob Ocelot's Avatar
 
🎧 10 years
Quote:
Originally Posted by Jesse Skeens ➡️
Wouldn't that be a high pitched whine?
Yep. 990 display also has an LED backlight so there's no high voltage inverter, and thus no whine when the display dies.
Old 26th May 2021 | Show parent
  #489
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Cpl. Punishment's Avatar
 
Quote:
Originally Posted by Jesse Skeens ➡️
Wouldn't that be a high pitched whine?
Yes it would.

Generally that buzzing is from the transformer in the power supply, which is an indication it's going downhill. The iron core in a transformer isn't a solid piece of iron, but a lot of thin plates that have been dipped into an specialized epoxy called transformer varnish and laminated together.

The buzzing you hear is generated when that varnish starts cracking and wearing away due to friction caused by the pulsing electromagnetic field that is switched on and off 60 (or 50) times a second. This buzzing will only increase and eventually lead to catastrophic failure as the same coating on the windings is also on the copper wires, and when those wires touch, a dead short occurs and bad things happen.

The good news is you can repair this yourself if you have a vacuum chamber and some transformer varnish. Remove the transformer and preheat it to 220deg/F for two hours, then place the transformer in a vacuum chamber with enough varnish to completely submerge, and pull a vacuum for 10 minutes (no air bubbles are present) and allow the varnish to invade any voids. Break the vacuum (this also draws the varnish into depressurized voids), and drain excess varnish for about 10 minutes. Then cure the transformer in an oven at 220deg/F for 8-12 hours, removing any solvents in the varnish and hardening it.

When you reassemble your power supply, I recommend using tiny silicone/rubber O-rings where the transformer joins to the case and the point at the head of the screw and the transformer. This helps isolate the vibration of the transformer (all transformer vibrate) and dampens the vibration transferred to the case. Use Locktite or super glue on the nuts to secure them in place so they don't vibrate loose.

Most motor rebuilding shops can re-varnish your transformers for a small fee as they're set up for that operation.
Old 26th May 2021
  #490
Lives for gear
 
🎧 10 years
Regarding the display, that's exactly right. The 990 display has an LED backlight and therefore has no inverter, so it's dead silent.

My Wavestation A/D, which still has an electroluminescent backlit display (circa ~ 2001) and not an LED backlight, does have that nasty high-pitched whine, and that's a very different sound than mains hum.



Back to the 990, I don't think it made this noise before, and it sounds like no one else's 990 (even in N America with 120V / 60 Hz) produces this hum, so Im starting to agree with @ usedtohaveajuno that my 990 needs to get serviced.

According to page 20 of the 990 service manual, later batches, serial numbers ZE-92300 and above, seem to include some sort of hum reduction feature, but the English translation is tough to parse.

My 990 serial number is a ZF, so it should include the hum reduction feature. I'm guessing that the hum reduction feature has failed or some internal cables or jumpers got dislodged during my move.
Old 26th May 2021 | Show parent
  #491
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by Cpl. Punishment ➡️
Yes it would.

Generally that buzzing is from the transformer in the power supply, which is an indication it's going downhill. The iron core in a transformer isn't a solid piece of iron, but a lot of thin plates that have been dipped into an specialized epoxy called transformer varnish and laminated together.

The buzzing you hear is generated when that varnish starts cracking and wearing away due to friction caused by the pulsing electromagnetic field that is switched on and off 60 (or 50) times a second. This buzzing will only increase and eventually lead to catastrophic failure as the same coating on the windings is also on the copper wires, and when those wires touch, a dead short occurs and bad things happen.

The good news is you can repair this yourself if you have a vacuum chamber and some transformer varnish. Remove the transformer and preheat it to 220deg/F for two hours, then place the transformer in a vacuum chamber with enough varnish to completely submerge, and pull a vacuum for 10 minutes (no air bubbles are present) and allow the varnish to invade any voids. Break the vacuum (this also draws the varnish into depressurized voids), and drain excess varnish for about 10 minutes. Then cure the transformer in an oven at 220deg/F for 8-12 hours, removing any solvents in the varnish and hardening it.

When you reassemble your power supply, I recommend using tiny silicone/rubber O-rings where the transformer joins to the case and the point at the head of the screw and the transformer. This helps isolate the vibration of the transformer (all transformer vibrate) and dampens the vibration transferred to the case. Use Locktite or super glue on the nuts to secure them in place so they don't vibrate loose.

Most motor rebuilding shops can re-varnish your transformers for a small fee as they're set up for that operation.
Thanks for this info!

Doing this work myself is out of the question, and I don't think there are any local repair shops that could do it either. Very few shops these days can take on labor-intensive electronics repairs and still break even.

Assuming my hunch about the 990's hum feature is incorrect (see my post above) , the best bet is probably just to send it in and have the entire transformer replaced.
Old 26th May 2021 | Show parent
  #492
Lives for gear
 
Cpl. Punishment's Avatar
 
Quote:
Originally Posted by gear_up ➡️
Thanks for this info!

Doing this work myself is out of the question, and I don't think there are any local repair shops that could do it either. Very few shops these days can take on labor-intensive electronics repairs and still break even.

Assuming my hunch about the 990's hum feature is incorrect (see my post above) , the best bet is probably just to send it in and have the entire transformer replaced.
You might be surprised at how many electric motor repair shops there are in any given semi-metropolitan areal; almost all of them are equipped to re-varnish stator windings. But even if you don't have one in your area, there are places you can have this sent off.

Getting that transformer replaced is a bit of an issue as the JD-990 power transformer is either a 110/220VAC primary (no multitap AFAIK) with taps for 15 and 5 VAC on the secondary -- not an "off-the-shelf" product, so that would require custom re-winding or cannibalizing other Roland gear which used the 22455641UO transformer.

If you think the noise reduction is fouled, that should be easy to fix with the o-rings I mentioned above (I prefer silicone because they don't dry out and become brittle like rubber).

In any event, best of luck with your JD990 -- I'd be interested in what you ended up doing and how it worked out.
Old 26th May 2021 | Show parent
  #493
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by Cpl. Punishment ➡️
You might be surprised at how many electric motor repair shops there are in any given semi-metropolitan areal; almost all of them are equipped to re-varnish stator windings. But even if you don't have one in your area, there are places you can have this sent off.

Getting that transformer replaced is a bit of an issue as the JD-990 power transformer is either a 110/220VAC primary (no multitap AFAIK) with taps for 15 and 5 VAC on the secondary -- not an "off-the-shelf" product, so that would require custom re-winding or cannibalizing other Roland gear which used the 22455641UO transformer.

If you think the noise reduction is fouled, that should be easy to fix with the o-rings I mentioned above (I prefer silicone because they don't dry out and become brittle like rubber).

In any event, best of luck with your JD990 -- I'd be interested in what you ended up doing and how it worked out.
Thanks Cpl! This is great info.

I made a little bit of a discovery just now. I tried running my 990 through a Japanese step-down transformer to bring the voltage down from 120V to 100V, and. . . the hum got quieter.

What does that tell you? Could there be something wrong with the mains power coming into my room?

Last edited by gear_up; 26th May 2021 at 06:31 PM..
Old 26th May 2021 | Show parent
  #494
Lives for gear
 
🎧 10 years
oops did not catch that it was a "physical hum" not line noise.
Old 26th May 2021 | Show parent
  #495
Lives for gear
 
Cpl. Punishment's Avatar
 
Quote:
Originally Posted by gear_up ➡️
Thanks Cpl! This is great info.

I made a little bit of a discovery just now. I tried running my 990 through a Japanese step-down transformer to bring the voltage down from 120V to 100V, and. . . the hum got quieter.

What does that tell you? Could there be something wrong with the mains power coming into my room?
It's hard to say without actually being there with some test equipment, but that sounds a lot like DC voltage leaking into your AC line, and dropping the AC voltage with your step-down transformer filtered it out by isolating the circuit at the stepped-down output AC voltage. If you had just an isolation transformer with a 1:1 ratio of windings on the transformer and that same phenomenon occurred (no more hum), then I'd say that's most likely the culprit.

Another possibility is the filter capacitor(s) as these have a greatly shortened lifespan relative to all the other components, or the choke. Possibly even one or more diodes in the rectifier.

[ . . . delay . . . ]

Now that I'm looking through the service manual, it says the main transformer is a "universal" transformer for 100/120/220/240 volts. It *could* be your transformer is wired to the 100v terminal when it needs to be at the 120v.
Old 26th May 2021 | Show parent
  #496
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by Cpl. Punishment ➡️
It's hard to say without actually being there with some test equipment, but that sounds a lot like DC voltage leaking into your AC line, and dropping the AC voltage with your step-down transformer filtered it out by isolating the circuit at the stepped-down output AC voltage. If you had just an isolation transformer with a 1:1 ratio of windings on the transformer and that same phenomenon occurred (no more hum), then I'd say that's most likely the culprit.
But if that were the case, wouldn't all my other gear be affected too? Wouldn't everything hum if DC voltage were leaking into the AC line?

Quote:
Originally Posted by Cpl. Punishment ➡️
Another possibility is the filter capacitor(s) as these have a greatly shortened lifespan relative to all the other components, or the choke. Possibly even one or more diodes in the rectifier.
This seems more likely, although I would expect other 990 owners to experience the same thing. Filter capacitors might not degrade at the same rate from 990 to 990, but no one else seems to have reported the same symptoms.


Quote:
Originally Posted by Cpl. Punishment ➡️

[ . . . delay . . . ]

Now that I'm looking through the service manual, it says the main transformer is a "universal" transformer for 100/120/220/240 volts. It *could* be your transformer is wired to the 100v terminal when it needs to be at the 120v.
That's easy enough to check, but seems highly unlikely.

Thanks again!

I'll open up the unit tonight and report back.
Old 28th May 2021
  #497
Lives for gear
 
🎧 15 years
Quick FYI ...

The 3rd party data cards that work in the 990 have been available lately if anyone is interested. Just got mine, a 256, and it works fine.

Some info if anyone needs it:
One 256 card stores 16 banks of 990 sounds, without a battery. The 990 sees each of the 16 memories as a separate card, so the only complication seems to be that you have to run the 990’s card format procedure each time you use a particular card memory for the first time. You choose the card memory you want with dip switches—You can change the switches from the exposed end of the card, while the card is plugged in and the 990 is powered up.

fwiw. (I am not affiliated with this company.)

https://sagamusix.de/other/roland_memory_cards/
Old 2nd June 2021 | Show parent
  #498
Lives for gear
 
🎧 10 years
got one as well thanks
Old 29th June 2021 | Show parent
  #499
Here for the gear
 
🎧 10 years
After living in regret for a year after selling my previous one, managed to find a mint condition one locally in South Australia for $1250AU, including the Vintage Synth expansion and M256 memory crd.

The feeling of loading up Deep SEAmphony and playing a chord is very hard to replace
Old 2nd August 2021 | Show parent
  #500
Gear Addict
 
Pilotwings's Avatar
 
🎧 10 years
Quote:
Originally Posted by Don Solaris ➡️
I can't think of any digital hardware synth with its value increasing over time, instead of decreasing. This begs questions:

-- How long before it reaches $1000 with Vintage expansion? LOL!
-- Are the alternatives in software really that bad?
-- What's so magical about it?
I sold one of my 990’s to a forum member here last August for $600 thinking I still have my original JD, but didn’t realize how many sequenced songs I’ve done using both at the same time. I know I could record separate takes into Logic with one unit, but there’s one for sale locally with the vintage board and I’m thinking of buying another one back for your crazy thousand dollar 2017 price! 🤦‍♂️

The Roland JD-990 and Yamaha FS1r are the only 2 digital pieces of gear I’ve kept since new. I don’t know if I should pull the trigger on the 990 or get a V-Synth for the same price. It’s not often these are for sale locally, and the prices keep going the wrong way (as a buyer). Decisions 🤔
Old 2 weeks ago | Show parent
  #501
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by Cpl. Punishment ➡️

Another possibility is the filter capacitor(s) as these have a greatly shortened lifespan relative to all the other components, or the choke. Possibly even one or more diodes in the rectifier.
Good guess, Cpl. Punishment. I just got my 990 back today from the repair shop.

The filter cap was indeed in bad shape, and that caused almost every other cap on my 990 to degrade also. Luckily nothing else was damaged.

My 990 is now fully recapped and recalibrated and, display permitting, ready to go for another 25 years.
Old 2 weeks ago | Show parent
  #502
Lives for gear
 
usedtohaveajuno's Avatar
 
🎧 5 years
Quote:
Originally Posted by gear_up ➡️
Good guess, Cpl. Punishment. I just got my 990 back today from the repair shop.

The filter cap was indeed in bad shape, and that caused almost every other cap on my 990 to degrade also. Luckily nothing else was damaged.

My 990 is now fully recapped and recalibrated and, display permitting, ready to go for another 25 years.
Plug and play display available on ebay - a few of us recently fitted them, so at least it's been done, if you need one in future!
Old 2 weeks ago | Show parent
  #503
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by usedtohaveajuno ➡️
Plug and play display available on ebay - a few of us recently fitted them, so at least it's been done, if you need one in future!
Thanks, I actually have a backup yanked from a dead JV-2080, however I will pick up the one you guys recommend as well.

FWIW, my current, original display is easy to read on contrast settings 1, 2, and 3, but is difficult to read on setting 4.

How much time is left on it? A few years?
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