Chuck Williams Fan Mod, WOW!! - Page 8 - AVS Forum
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post #211 of 231 Old 02-03-2003, 09:14 AM
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Chuck sent me the updated version for an NEC a week ago. I don't think he'd mind if I hosted it here.

Jerry
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post #212 of 231 Old 02-03-2003, 12:36 PM
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Hi Guys,

Glad to see this has come along this far! Though I've swapped all my fans, I'd love to add this circuit to all but the 3 CRT fans on my Sony 1292Q. Has anyone etched boards, and built circuits ready to solder in? I'm okay with an iron, but lameless at understanding circuits, etc.

Thanks in advance for your help! :cool:

Brett
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post #213 of 231 Old 02-05-2003, 03:46 AM
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Bump! :)

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post #214 of 231 Old 02-06-2003, 11:45 AM
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Hmmm,
I put one of the earlier fan mods from Chuck in a XG1101LC yesterday but couldnt get it to work, fans are trying to come on just not enough kick, anyone find this? Its was for the PG-XG and the design looks to be the same as the latest.

I get 6.5V to the fans under load and 8.2V with no load. This was from a while ago that I just had enough time to go do. I wasnt doing the test with the two power supply fans. I was tapping in at inductors 5005-5006 on the HV power board and the input voltage was correct . Thanks, Doug
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post #215 of 231 Old 02-06-2003, 01:22 PM
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Does'nt that mod incorporate a timer IC that starts it on full voltage than drops to a lower voltage? Here's my simplistic approch to the problem. I don't know if this is doable on a low voltage motor but, would it be possible to lower your voltage to the fans and add a starting capacitor to bump the fans into motion. Once it's in motion, I'm sure it would continue to rotate. In the HVAC industry there is a product called "Jump Start" that can be added to a non cap-start motor to aid in starting. If that design could be copied on a smaller scale it would solve the problem.

Chip S.

Current owner of the last/best AmPro on the planet. The mighty 4600HD, and it's still running...better than Barco's, especially southern ones.
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post #216 of 231 Old 02-06-2003, 01:48 PM
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Chip,
Yes, from what I can tell its not getting the 'Kick' unless I did it wrong, one possibility is the LC has an extra fan connector on the HV board and what I thought it might be. Doug
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post #217 of 231 Old 02-06-2003, 08:11 PM
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Doug, I just installed the mod on an XG1350. With no load I had 15V whether the circuit switched or not (normal, since there isn't current flow to drop voltage with no load). With a load, I have 15V at startup and 7.5V after the circuit times out.

I tapped in around where you did (although my diagram says 5505, 5506). The way I tapped was by pulling the jumpers; IJ5504,6,8...16. Then I used the hot side IJ5516 to feed the mod 15V and connected the output of the mod to the load side of IJ5516 and jumpered the nonfan side of resistors R5509,11...19 and R5523 & 25. I then connected the mod's ground to pin 3 of PF09 (PF09 is not used on the 1350).

Jerry
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post #218 of 231 Old 02-06-2003, 09:05 PM
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Jerry,
I think the non and LC unit is just enough to stop the fans, Seeing you had 7.5 volts with the non LC and I had 6.5V with. Ill have to wait for Chuck to determine the fix for the LC, it does have one more fan. Thanks much. Doug
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post #219 of 231 Old 02-07-2003, 07:02 AM
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Doug,
The extra fan shouldn't matter, the load current is sourced through the NPN pass transistor (2sd613). It sounds like either there is a wiring error in the circuit or the pass device is defective(emitter base is degraded or shorted). With the circuit on you should see the zener voltage plus a sat at the base of the 2sd613, approx. 7.5 to 8v. The emitter voltage should be this voltage minus a Vbe, approx. 7.2 to 7.5v. Measure these values with a load and no load and see what you get. From your previous measurements it shows no regulation at the emitter, therefore the current is taking a resistive path causing the voltage drop you are seeing. Make sure you take the measurement right at the emitter, there could also be a voltage drop between there and the fan connection, solder joint?
Kevin
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post #220 of 231 Old 02-07-2003, 08:15 AM
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Jerry, Kev,
Much thanks, Im going back out there today, I did take the measurement at the emitter. I just dont see the regulation working. Solder joints are ok. Doug
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post #221 of 231 Old 02-07-2003, 10:37 AM
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I don't think it makes much difference as far as the number of fans since I bench tested it with 1 fan, then installed it for only the ~6 fans connected to the HV board, then added the Power supply fans. The mod functioned basically the same. More fans (load) could spell more voltage drop but it didn't make a 1V difference in my case.

From what I've seen of the circuit in action, I'm guessing the 2SD613 is mostly a switch to short across the 33ohm resistor during startup and then opens up (or at least conducts less) so that all the current goes through the resistor and that's what reduces the fan voltage. I noticed that the resistor warms up after the timeout but the 2SD613 is only warm during startup (when all the current is going through IT) and then gets cooler.

For anyone wondering, the mod does a great job but it seems you need to include the power supply fans or the change was only about 25%. The PS fans have enough of a buzz to them that quieting the other fans only seemed to make the PS ones more apparent. Now I can't even hear the PS fans once I added them.

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post #222 of 231 Old 02-07-2003, 11:26 AM
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Quote:
From what I've seen of the circuit in action, I'm guessing the 2SD613 is mostly a switch to short across the 33ohm resistor during startup and then opens up (or at least conducts less) so that all the current goes through the resistor and that's what reduces the fan voltage. I noticed that the resistor warms up after the timeout but the 2SD613 is only warm during startup (when all the current is going through IT) and then gets cooler.
Jerry,
Looking at the circuit, it's actually the other way around. The 613 is off at startup and the fan current is supplied through the 33 ohm pullup to 15V, this gets the fans going. Once the 613 is turned on, it's emitter voltage is regulated by the zener voltage applied to the base minus a vbe which is approximately 7.5v depending on component variation. The 33 ohm resistor is now dropping the difference between the regulated voltage at the emitter and the 15v rail, approximately 7.5v causing it to dissipate about 2 watts, which is why it is warm to the touch or burning if you leave your finger on long enough.:D
Kevin
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post #223 of 231 Old 02-07-2003, 03:46 PM
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Oh this is so much fun...;)
Quote:
The 613 is off at startup and the fan current is supplied through the 33 ohm pullup to 15V, this gets the fans going. Once the 613 is turned on, it's emitter voltage is regulated by the zener voltage applied to the base minus a vbe which is approximately 7.5v depending on component variation.
Kevin, you got me thinking about this so I checked a few more things and I'm sticking with my original analysis. With a voltmeter connected from C to E on 2SD613, there is only a 1V drop across it during startup so that means it is ON and conducting 14 of the source 15V. After the timeout the voltage E to C rises to about 7.5V which means it is at least 1/2 off or the 5W resistor is dropping it and less is getting to the fans.

The 33ohm resistor can't act as a pullup because it's in series with the load. The more current (load) that it passes, the more it drops (E=IxR). I tried connecting only 1 fan in series and the voltage to the fan dropped from 15 to 12V. More fans make it drop even lower (like to 7.5V :) )

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post #224 of 231 Old 02-07-2003, 05:30 PM
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Jerry,
OK, then that would mean the timer circuit is doing the opposite of what I assumed, which it doesn't. The output of the 555 goes low after the timeout, turning off the 2n2222, this allows the bottom 2n2222 to be turned on and light up the zener through it's 100 ohm shunt. It seemed obvious that this was a regulator circuit and you would think that's how it would be used. However the parallel 33 ohm resistor is defeating the transistor action at light load, hence the reason you see 12.1v with only one fan. I understand the E=IR concept perfectly well, and it is conceivable that with currents small enough that there is enough voltage to start up. However, looking at it again it now seems that you are right and the fan voltage relies somewhat on an IR drop, not as robust as I would like it because there is no load regulation. The ideal situation is to have a specified voltage independent of load variation, a problem now seen with Doug's situation. The fact a zener is in the circuit suggest it was used as a regulator at some point, I think there may have been an oversight during a circuit change or it was just designed to work with only one specific load requirement. I would probably tweak this circuit a little so that it works as a regulated voltage source independent of load.
Kevin
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post #225 of 231 Old 02-07-2003, 10:28 PM
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Update,
Im just not seeing the regulation. I dont see the kick at all or where the timer is timing anything. Ground is ok, 15V is ok (in). Im thinking the load does have an affect. Voltage was read at the emitter. I brought it home to do more checking but we finally have Nascar starting tomorrow so thats has priority. Doug
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post #226 of 231 Old 02-08-2003, 04:47 AM
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Doug, check the base of the 2SD613. It should be 15V during the timeout, then 7.5 after.

Jerry
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post #227 of 231 Old 02-08-2003, 06:44 AM
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Doug,
Adding the extra fan shouldn't drop the voltage more unless the transistor isn't turning on which sounds like it may be the issue. Make sure pin 3 on the 555 goes high on power up, this keeps the bottom 2n2222 off allowing the 613 to switch on hard through the 100 ohm resistor connected to the base.
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post #228 of 231 Old 02-08-2003, 07:10 AM
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Oh Jerry,
I meant to say in my explanation above that you are right about the 613 turning on at startup, at first glance I missed the 100 ohm acting as a base resistor when the zener is off. However the 12.1v you're seeing with one fan is explained in my post above. Some of the current is shunted through the 33 ohm resistor, at light load this becomes more significant as the emitter voltage rises, stopping the base from turning on. The resistor helps to share some of the load, but at the cost of load regulation. If you just remove the resistor and allow the transistor to have control you would just have to make sure you have a good heat sink that's capable of at least 10W, assuming the total fan current is below 1 amp.
Kevin
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post #229 of 231 Old 02-09-2003, 12:51 PM
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Hi Guys,

Sorry to be a little off-topic, at least off the technical part of the topic.

Chuck told me that some of you asked for his circuit to mod your Sony 1292s - has anyone had success or issues with this circuit on that projector?

Thanks in advance,

Brett
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post #230 of 231 Old 02-10-2003, 06:44 AM
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Quote:
Originally posted by DHarp193
FYI, there is also a fan mod for the Electrohome Marquee line of projectors that quiets the noise considerably for all you Marquee owners out there!!!

Tim Martin knows how to do it, as well as myself and a few others if interested.
I'm interested of all things to do with a Electrohome Marquee 8500!!!!
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post #231 of 231 Old 04-26-2003, 06:12 PM
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I'm not all that comfortable going inside the projector. I"ve never owned one before. I'd like to quiet my XG 110LC. Does anyone have photos please? It would be greatly appreciated!
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