sulaco
join:2000-11-27
Parker, CO | reply to bobsmith123
Re: Cayman 3220-H running hot with stock Power Ada
I just bought the rat shack 9V 1.5a power supply. It works great and runs much cooler. |
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bobsmith123
join:2000-12-23
Sacramento, CA
| reply to DocWonder
Re: Cayman 3220-H running hot with stock Power Adapter
I found a 8.5 volt DC 1 amp fused regulated power supply lying around here somewhere. I think I got it from my brother a while ago for a project I never got around to, anyhow, would this be safe to use? It a huge supply in a heavy-duty aluminum case. weights like 7 pounds. I could get my bro to wire it to the cayman. |
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WB6PWJ
join:2004-05-12
Anaheim, CA
 ·VOIPo
| reply to DocWonder
The voltage must be above the regulater min. As I recall a 7805 for example has a 2.5 to 3v difference. at 5V I would not feed less than eight. Later designs require less but they all must have more input than output. The problem is that that difference is thrown away as heat. With a large heat sink you could run twenty volts into the regulater. All that would do is heat up the cabinet. The reason that switching regulaters are prefeered is that they can run at 90% efficentcy. The 7805 in the above example would be 25% at 20v. 50% at 10V, etc. |
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DocWonder
join:2003-01-11
Miami, FL | reply to public
So a 6.5 V 2.0A switching power adapter is the final answer? |
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WB6PWJ
join:2004-05-12
Anaheim, CA | reply to public
I have been running my 3220H for years on an eight volt switching wall wort intended to power an IBM printer. The unit runs much cooler than with the stock analog one that in my case measured 11V under load. |
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public
join:2002-01-19
Santa Clara, CA
 ·DSL EXTREME
| reply to Dogwood
said by Dogwood  :
The internal power supply has always been an issue with the 3220-H, and was probably undersized from the beginning.
My solution was to install the fan set you see here.
Let's put an end to this once for all.
Internally the 3220 uses two supplies. 3.3V and 5V. When Cayman designed this unit, they did not have much in house design expertise. The purchased a switching converter module for the 3.3V supply, and when this exceeded cost budget they decided to use a 5V linear regulator with a dinky little heat sink for the 5V supply. This is the hottest part in the whole box.
To minimize heat generated by the 5V regulator use the lowest external supply which will guarantee proper operation. This is about 7Vdc regulated.
Most of the cheap cubes are unregulated, hence they used higher voltage so that the combined ripple and AC variation will stay above 7V.
Therefore if you use external regulated 6.5 to 7V supply you will minimize heat generated inside the box. |
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Dogwood
Premium
join:2001-01-14
Texas
clubs: 
| reply to DocWonder
If the external power supply, wall wort, is getting too hot, then it may be going bad or undersized for the load.
Keep in mind that a good PS does get very warm normally.
The internal power supply has always been an issue with the 3220-H, and was probably undersized from the beginning.
My solution was to install the fan set you see here.
--
Proud Member of: Team Discovery
BroadbandGaming
BBR ET Clan Leader BBr|ET |
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public
join:2002-01-19
Santa Clara, CA
·DSL EXTREME
| reply to DocWonder
that means that it is using 9VA to run or about 1amp of draw, with some lost to heat. with a 6v power supply, you would DRAW 1.5 amps. either way you figure it, you draw more current with lower voltage. more current in the same circuit=more HEAT to lose
Before you start inventing perpetual motion machines read up on basic electricity. |
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public
join:2002-01-19
Santa Clara, CA
·DSL EXTREME
| reply to DocWonder
said by DocWonder :
Are there any electrical engineers in the house? Who is really familiar with the workings of the Cayman 3220 What is the best power adapter for this Router? What power adapter would reduce the excessive heat produced by the router?? Thanks for any help!
The amount of ignorance is truly amazing, kind like the call center Indians.
The 3220-H uses a 5V 7805 linear regulator. Therefore the most appropriate power supply is a regulated 6.5V supply. Regulated means regulated. Therefore when the AC fluctuates the output remains the same.
The universal input wall warts will take 90- 240 VAC in to produce 6.5V out.
Later Caymans use a switching regulator on board, so that the input does not matter. |
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DocWonder
join:2003-01-11
Miami, FL | reply to dgilbert
Re: Cayman 3220-H running hot with stock Power Ada
thanks for the info... that clears up the the issue. The power supply i have is a 9V 1.5A... so i guess there's no worry. I did put a 1A on a for a little bit and it got HOT! So I'll be sticking with the current Power Adapter. |
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dgilbert
Good Bye My Friend
Premium,MVM
join:2002-06-15
none
clubs:
1 edit | reply to DocWonder
just because the PS is RATED at 1.5 or 2A, does NOT mean it is delivering that much. it will only deliver the rated voltage up to that amount of current, draw more current and the voltage starts to drop. in this case, we don't need to figure on resistance, since resistance is not the only factor in the equation. we need to look at POWER, P=V*I. so, using your examples, and keeping in mind that POWER is our constant, we get:
9V*1.5A=13.5VA or Watts since this is DC.
now, by taking a 6V supply, we must adjust current to equal the same power.
13.5/6=2.25A
therefore a 2 amp power supply will not cut it, IF all power is used for running the unit, and none is lost due to heat. in reality, there is significant heat lost due to the inefficiency of the unit. Regardless, the unit is still going to consume the same amount of power to run the circuits and is still going to lose close to the same amount to heat. the regulator WILL work when fed by at least 6 volts, but the problem comes in when your power supply dips below the minimum 6 volts the regulator delivers to the rest of the circuitry. if your borderline rated (6V-2A) power supply dips to 5.5 volts, then the regulator can no longer put out 6 volts. it will try, but it can't do it. therefore, vital circuits run on low voltage which INCREASES their current draw and causes them to fail sooner or to corrupt data. this is why units not run on UPS often have corrupt firmware, the brown outs lower the voltage to a point that the unit goes stupid and corrupts NVRAM.
so, my point is why would you knowingly put yourself right at that threshold? a good rule of thumb is to always use a power supply that is rated so that current draw is only about 60%-70% of the PS max to keep it from failing or dropping voltage under load. keeping that in mind, assume the cayman only draws about an amp. that means that it is using 9VA to run or about 1amp of draw, with some lost to heat. with a 6v power supply, you would DRAW 1.5 amps. either way you figure it, you draw more current with lower voltage. more current in the same circuit=more HEAT to lose!
to summarize, the lower your voltage the more current you draw. the more current you draw in a FIXED circuit, the more power is lost to heat and the less efficient the circuit becomes, as the heat leads to MORE resistance in the circuits.
keep in mind that as long as the supply voltage stays above 6 volts, the internal 6V regulator is going to be what takes the abuse. but let it drop below 6v and EVERYTHING takes the abuse.
it just does not make good sense to go with a lower voltage supply. regulators are designed to regulate a minimum input voltage to a set output voltage. excess power is blown off via heat loss, but this is figured into the rating of the regulator.
best bet is to use a fan or two, or if you a comfortable with electronics you can put a heat sink in on the regulator to disipate the heat more evenly and quicker. either way makes for a cooler running device.
EDIT:
and yes, these temps are well within specs. i have approximately 40 3220 units in service, and they all run fine with factory PS. i don't even try to cool them. i just set thin in areas that they will get good air flow.
BTW, if you search back a ways you will run across threads referencing bad power supplies for the 3220. those were replaced with 9v 1.5a PS. the old PS was 1.4A. this PS got hot and delivered low voltage and caused the 3220's to fail. again, this is due to the POWER the 3220 draws is a constant. the 1.4A was barely above the needed supply and therefore failed early. the same thing applies on the voltage side, so a 6V supply will run too hot and cause failure unless it is rated to at least 2.25A, preferably more.
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If you can read this, thank a teacher..........and since it's in English, thank a soldier. |
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DocWonder
join:2003-01-11
Miami, FL
1 edit | reply to dgilbert
lol... aftermarket fans for the cayman router? You'd think cayman/netopia would at least suggest or recommend a solution. Then again, maybe it is well within specs for the cayman to run that hot. My real question is what is teh best power adapter. Let's put together a list of what's been tried and its results.
9V 1.0 mA Linear Power adapter - result: hotter than stock adapter. Conclusion: Using a linear power adapter with lower then recommended current results in excessive heat. Let's see if this makes sense: Ohm's law states V=I*R (V=voltage, I=current, and R=resistance (heat))
V=9V and I=1.0,
R=V/I which means R=9
the stock adapter is also 9 volts, but with a I=1.5, therefore in that case the R=9/1.5, R=6.
By following ohms law, we can conclude that the solution may be to purchase a power adapter with a higher Amps. Throw in the SWITCHING power adapter and we may have a more stable solution. So what do you guys think?
But just anotehr thought... that's only as far as the power adapter... once we get into the cayman router tho, it may be entirely different... the router has fixed resistors inside, undoubtly rated for a certain Ohm. The higher the ohms the hotter the unit gets. providing a power adapter that as a lower current has proved to increase the amount of resistance. R=V/I... anotehr solution would be to lower teh voltage. But would teh cayman work if you lower the voltage? |
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dgilbert
Good Bye My Friend
Premium,MVM
join:2002-06-15
none
clubs:
| reply to DocWonder
the BEST thing to do is to get a couple of small muffin fans and mount them over the vent on the top of the 3220(a little glue will go a long way). have them blow in the unit, this will keep it cool as a cucumber. run these fans off the proper size transformer, these are readily available at radio shack or other electronics stores/depts.
varying the supply voltage is NOT the answer.
--
If you can read this, thank a teacher..........and since it's in English, thank a soldier. |
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DocWonder
join:2003-01-11
Miami, FL
| Cayman 3220-H running hot with stock Power Adapter
A while back ago someone posted something about the heat issue experienced by many Cayman 3220-H when using the AC power adapter supplied with the router.
Some ppl suggested that the stock power adapter was of poor quality and that simply going out to radio shack and buying a better quality 9V 1.5A linear power supply solved the problem.
Another suggested that the Cayman actually runs off a 5V regulator and merely requires a 6.5V 2.0A SWITCHING regulated power adapter.
Others argued that getting a higher Current power adapter is a sure way to fry your cayman, but others rebutted with the device will only take as much current as needed.
Are there any electrical engineers in the house? Who is really familiar with the workings of the Cayman 3220 What is the best power adapter for this Router? What power adapter would reduce the excessive heat produced by the router?? Thanks for any help! |
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