Temperature of Digital Computer Organs

[myorgan]

Folks,

Since I move my Allen organs from place to place, I've had questions about operating temperatures and change of temperatures. In a recent thread, a conversation came up about how damaging it can be for electrolytic capacitors going from one extreme temperature to another or being operated at extreme temperatures. IIRC, it was more damaging to caps to experience consistently high temperatures. My question is how to warm up an organ from freezing, or close to freezing to an operating temperature.

Is it better to turn on the organ when cold and let the heat from the amplifiers, etc. gradually warm up the organ? Or is it best to allow the organ to warm up to 50˚-60˚ before turning the organ on? I remember reading in the thread that the capacitors encounter less failure rate at low temperatures than high temperatures.

I do know that at first, I used a quilted organ cover over the organ when it had gone below freezing. That way, the organ would warm up gradually under the stage lights while off. However, I noticed that allowing the organ to warm up inside the cover created condensation/moisture inside the organ as it warmed up, and have in later years allowed it to warm up without the cover. That appears to have solved the condensation issue, but I've wondered about the relative humidity inside the organ case and whether it would be better to turn it on at the lower temperature, and the heat of the organ's electronics would take care of the condensation as it warms.

What do y'all think?

Michael

[indianajo]

Since I move my Allen organs from place to place, I've had questions about operating temperatures and change of temperatures. In a recent thread, a conversation came up about how damaging it can be for electrolytic capacitors going from one extreme temperature to another or being operated at extreme temperatures. IIRC, it was more damaging to caps to experience consistently high temperatures. My question is how to warm up an organ from freezing, or close to freezing to an operating temperature.

Having worked in a factory that went from 15 deg F on cold starts in the winter, to 110 deg F in the summer, and 130 deg F in the motor drive compartments of the ovens, I have an opinion. **** caps will fail at one extreme or the other. I presume because of the low quality rubber sealant they use.
excellent caps are not affected by either. I presume silicon seal rubber is used or equivalent, as niether condition seems to matter much to some brand of VFD motor drives using huge 400v cap banks.
One line of **** caps was CDE flatpack, that seemed astute at taking out Semi VFD drives on cold morning with a puddle of cap slime in the bottom of the case, after 3 -4 years service. One line of excellent caps were the nichicon caps found in TB Woods motor drives, that seemed up to performaing at 130 deg in oven motor comparttments, and started right up on cold mornings with no complaints. Hint, nichicon also sells 500 hour caps, it is up to the vendor to buy the good ones if he wants them. I just took some United Chemicon caps out of an Allen Bradley 2007 motor drive that also had a stellar reputation. As the United Chemicon datasheets have some very favorable conditions in their concept of a life spec, I would presume you can't buy this long life quality of cap from a distributor of United Chemicon products two at a time. AB (siemens) gets what they want, and has an incoming inspection product to enforce the contract specifications.
IMHO the Allen did not use **** caps. I just (October)replaced the e-caps in an 1980 Allen S100 amp that had lived its life in a southern Indiana church not heated or cooled except during services. The building was stone. No slime had leaked but the volume was going to zero after 40 minutes of the service. I take that as life. I just measured them having bought an ESR meter this month, and no, David the caps causing the problem were not out of spec at room temperature. I did measure the speaker wires at the time and all were above 6.5 ohm, or in spec for 8 ohm speakers.
So, IMHO, don't worry. And if unreliability costs your $2000 an hour as it did at the factory, change your e-caps power amp or Allen organ at about 30years.

[jbird604]

As to warming the organ up, Michael, if it's been stored someplace really cold and you move it into a heated indoor venue, the condensation problem will be the worst thing to contend with. The cold metal parts, especially heavy items such as heat sinks in the amps and power supplies, and certain structural parts of the organ, are going to remain cold for quite a while. It's a given that the humidity in the room will turn into water droplets on these cold surfaces until the metal warms up enough to stop attracting the water.

Since some of this condensation will be happening in places you can't even see it (inside the ADC amp chassis or in the cage, for example), it can be a real nuisance and could eventually lead to corrosion or other damage.

The best way to stave off the danger is to open up the organ console as soon as you get it moved to the indoor/heated location. Remove the back and open the top lid too. Then place a fan behind it and let the air blow through the organ until the metal parts come up to room temperature. The moving air will help evaporate any moisture than condenses before it has a chance to do any damage. I wouldn't turn the organ on until it begins to feel like the temperature of the parts has stabilized.

Of course the downside to the moving air is that is brings even more moist air into contact with the cold metal, but the only alternative is to have the organ sealed air-tight (shrink-wrapped) and let it come up to room temperature before removing the wrap, which could take hours or even days. But my opinion is that using a fan is your best bet. You can monitor how well this is working by watching for water droplets on the exterior of some heavy metal part.

Back in the 80's I took care of a large ADC Allen on a university campus. Unfortunately, this organ was pressed into service about three times a year for graduation programs in the gym, so the university maintenance people would pick it up from the Fine Arts auditorium, load it into an open pickup bed, and haul the console across campus to the gym where it would be connected to a set of portable speakers left permanently in the gym. The temperature was sometimes below freezing, so the console would get thoroughly cooled on the journey. To make matters worse, the gym had a swimming pool, so the building was not only warm but humid. So once the console was brought inside it would start to get moist. Not to the extent it would've done if it had been stored in the cold, but enough moisture that it sometimes caused keys or drawknobs to get sluggish. A service nightmare of course for me.

There's no doubt that it ages an organ to move it around. The console gets road rash, the wooden joints may get stressed and eventually loose, electronic parts and capacitors in particular are stressed and aged by the temperature swings. But it can be a necessity to move a console for use in a symphony or other performance situation, so don't worry about it. Just do your best to take care of it.

[myorgan]

As to warming the organ up, Michael, if it's been stored someplace really cold and you move it into a heated indoor venue, the condensation problem will be the worst thing to contend with. The cold metal parts, especially heavy items such as heat sinks in the amps and power supplies, and certain structural parts of the organ, are going to remain cold for quite a while. It's a given that the humidity in the room will turn into water droplets on these cold surfaces until the metal warms up enough to stop attracting the water.

[snip]

The best way to stave off the danger is to open up the organ console as soon as you get it moved to the indoor/heated location. Remove the back and open the top lid too. Then place a fan behind it and let the air blow through the organ until the metal parts come up to room temperature. The moving air will help evaporate any moisture than condenses before it has a chance to do any damage. I wouldn't turn the organ on until it begins to feel like the temperature of the parts has stabilized.

John & IJoe,

Thank you so much for the information. Of course, IJoe, the quality of the performance is directly affected by the quality of the parts. John, thank you for the idea of the fan. I had always left the organ consoles closed because I thought it was the speed of the cooling or warming that would create the condensation. I remember when we went hunting, we'd either wrap the guns in a blanket, or leave them in their carrying case until they'd reached room temperature. My Dad always said that was to stave off rust on the barrel.

Then, I was under the mistaken impression that as the organ "froze" (cooled), the humidity would be forced out of the parts and freeze on whatever surface was around (kinda like freeze-drying food). I was under the impression I was re-hydrating the parts of the organ. On the organ in my garage, I have noticed that the closer it gets to freezing (in the 30˚sF, the higher the humidity (82-88%), and as the organ warmed, the humidity would go down (ca. 70% humidity at around 50˚-60˚F). That's what made me believe the humidity was coming out of the organ. I have the thermometer set inside the console next to the power switch (where most people put their music).

Someday, I should create an Excel chart of temperature vs. humidity over the next month or two, and see how the two measurements relate to each other.:o

Thanks again for the information.

Michael

[Nutball]

The only temperature problem I know of for caps is the max rated temp. I guess if it is rated for 3000hrs @ 85deg C, anywhere below that may extend lifetime, and anywhere above could greatly shorten the life. Outside temps shouldn't bother anything I know of. I wonder how it would sound if you froze it down to superconductor temps? Definitely ventilate it well long before it gets used. Cold foggy conditions while moving could cause future problems.

[myorgan]

The only temperature problem I know of for caps is the max rated temp. I guess if it is rated for 3000hrs @ 85deg C, anywhere below that may extend lifetime, and anywhere above could greatly shorten the life.

Nutball,

I'm not sure it's the low temperatures that cause performance issues, rather it's the expansion and contraction of an item when it freezes that could potentially stress it to the failing point. Fortunately, this Winter we've not had too many cold nights in the garage, and the lowest temperature inside the console has been in the high 20's a couple of times. Right now, it's reliably just above freezing because the slab under the garage didn't freeze this winter and the ground/slab are keeping the garage warmer than usual.

Thanks for the input.

Michael

P.S. Now, if I could afford the enclosed porch or garage replacement w/heated garage, then my problems would be solved!:-(