CurtPalme.com Home Theater Forum

Revox · Joined: 13 Feb 2008 Posts: 158

Good night, ill go to!

PaulB · Posted: Sat Sep 19, 2009 4:46 am Post subject:

Hmmm, ok Nash, you've got me slightly concerned now. Its been vaguely twirling in the back of my mind but this thread has focused my attention on this 24v to 12v stepdown.

I have 12v Noctua fans in both the LVPS and Belly. Both sets are just plugged straight in to their respective connectors, no stepdown convertors used at all, no resistors etc. Not good by the sounds of it, so;

1. Do I need stepdowns for Belly fans as well as the LVPS? (4 Noctua's in the belly).

2. Your pictures and Jarmo's diagram below - I can pretty much follow the diagram but what I'm not getting is how the diagram relates to the TWO fan connector heads on the LVPS. There are Two fan connectors on the LVPS, one for each fan BUT from looking at the diagram there appears to be only two wires going to the LVPS , one to the 24v and the other to the ground. So, are both fans being run off one connector OR (and I think this is correct) are there actually Four wires but they are just not shown in the diagram CORRECTION - Ah, I do see the FOUR wires at the top right blue connector output, yes? Yes, I'm sure thats it.

3. Theres also a white wire showing in the photograph - whats that doing there? Not connected I think but I'm not sure?

4. I see Revox just uses the 7812 with just the heatsink, no resistors/caps I presume - good idea?

This is how my Belly fans are currently wired;

Jarmo suggested this at one point to slow (reduce voltage) the fans;

I pretty sure CZ Eddie originally had the Noctua's wired the same way as I did it, i.e. no stepdown etc so I wonder how he's getting on? Eddie, any update on the fans?

Thanks

1031 · Joined: 22 Mar 2006 Posts: 657 Location: Finland

1. Do I need stepdowns for Belly fans as well as the LVPS? (4 Noctua's in the belly).

Paul, you can use two 12v fans connectet series at LVPS (not safest way if one of fans fails) or that 12v regulator.
With four belly fans it is same, connect 12v+12v and 12v+12v and connect those two fan series to parallel for 24v Or use regulator.

So, are both fans being run off one connector

At LVPS those two fan connectors are connected parallel so you can use one of those, doesend matter..

PaulB · Posted: Sat Sep 19, 2009 8:39 am Post subject:

Jarmo,
Sorry, I edited my post at the same time as you were posting.

Ok, I understand where I'm wrong with the LVPS - should use ONE connector only for the fans when used in series Thumbs Up

For the belly, do you still recommend using the inline resistor?

Thanks

Revox · Joined: 13 Feb 2008 Posts: 158

My LVPS Fans are in series too.
I think it's a good idea to add a resistor in front of the 7812 to reduce the electrical noise coming from the Fans.

I got a idea for cooling the Focusboard better:

I install a Heat sink on the standard heat sink thats as long as the board.
Maybe there is a little space for a second fan.

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1031 · Joined: 22 Mar 2006 Posts: 657 Location: Finland

PaulB · Posted: Sat Sep 19, 2009 9:37 am Post subject:

Thanks for your reply Jarmo, very reassuring. I'm happy just to correct the LVPS and leave the belly fans as is for the moment I think. The voltage regulator is clearly the ideal solution but with time at a premium and a simple fix available for the LVPS fans I'll pass on it for now and concentrate on the magnets.

Interesting idea about the extra heatsink to the focus board- must admit I have no real idea how hot the board gets, my pj is never on for more than an hour or so due to modding this that and the other and most times its barely warm when I take it out!

I'm trying to minimise the mods/tweaks so that I can try to sort out the magnets and watch a movie - not having much luck because you guys keep coming up with good/better ideas Evil or Very Mad

Maybe I should ban myself from the forum.

Anyway, I'm glad Rovox started this thread as its produced some good information that I badly needed to understand and implement!

Thanks guys Thumbs Up

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Paul the focus board does not get so hot that you can't touch it for longer than 5 seconds like Revox's. His is that Hot because he has the wrong fans, not enough airflow. in time his boards will over heat and something will go on it. heat is the enemy more than Noise, remember that. if the fans are too loud crank up the Volume on the stereo!! Wink

The belly fans are actually not as loud as the LVPS fans, if they do really bother you I have a theory that if you lower change the speed of each fan so they are not running at the same frequency the noise would be less, I have not tried this yet. so you keep one fan as is , say the one directly under the HDM, then you can put a resistor inline between the other two fans of different resistance , but not too much just enough to alter the frequency noise the fan creates. this way you do not have three fans all running at the same frequency amplifying that frequency x 3, make sense?

Athanasios

Revox · Joined: 13 Feb 2008 Posts: 158

I thougth that El-Cabs are the temperature mimosa's. So when only the transistors are running hot (for examble on the focus board) there will be no problem (when you say that temperature drift isn't a problem).
When my M runs for 3000 Hours i am satisfired.

So when i am back at home, ill test the temperatures of different boards!

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Paul in that above pic of my 12 volt power supply i only have one fan connected, I tested it with both fans connected tot he one output and it worked fine and the voltage while the fans running on the output side was 11.5 volts, with one fan it was 11.7 so the extra fan does not put too much draw, the caps and resistors are much better than Revox's method as they filter the noise and also store power for start up of the fans I assume, jarmo could explain it more.

Athanasios

Revox · Joined: 13 Feb 2008 Posts: 158

Are there information aviable of the NEC cooling Concept.
As i saw the STK screwd at the bottom without a heat sink are a problem.
What i'd like to try is put a graphic card cooler at the bottom of the PJ.
Eventally this cooling device fits between the focus module and the tube of the M as well. I need 3cm.
http://www.arctic-cooling.com/downloads/compatibility/hgt_restr_aclrox1.pdf
Cost: with shipment 7€

The Fan for the tube driver circuits is only to cool those ones?

How is the power supply cooled?

How to cheat on the "fan Guard" ?

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

yes paul thats ok, Revox replace your belly fans with the originals or something with more air flow and forget that processor fan .

Athanasios

PaulB · Posted: Sat Sep 19, 2009 5:34 pm Post subject:

I manged to delete my own post!! I'm going mad and getting worse by the minute!

What I'd said was;

Ok, I'm going to stop coming to this forum, I spend more time pottering around doing the mods and testing than I do actually getting the bloody pj installed. Sigh......!

Having said that, will a 2.2ohm .5w fusible resistor be ok for the voltage regulator (rather than a .6 which I don't have)?

1uf 100v cap is ok instead of 50v isn't it?

I swear to god, this is my last mod (other than line fix but after that....!).

Nash's reply is as above Thumbs Up

1031 · Joined: 22 Mar 2006 Posts: 657 Location: Finland

PaulB · Posted: Sat Sep 19, 2009 6:21 pm Post subject:

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

I still have to play with slowing down the cool cats, they run too fast as is with the 12 volt step down, the single power supply has enough to power all three and doesn't get too hot. but i want to go home now and try out different value Resistors on all three to see if the different speeds will reduce the over all noise of three of the same frequency noise.

Athanasios

PaulB · Posted: Sat Sep 19, 2009 6:47 pm Post subject:

LOL

PaulB · Posted: Sun Sep 20, 2009 8:00 am Post subject:

Ok, I'm going to go with the Thermaltakes for the Belly. I'll put in 4, my belly has already been modded for 4 fans so i'll need to put in a resistor to slow them down somewhat.

Just as "too little" airflow is bad, presumably "too much" airflow can be equally bad, yes? Too much could disrupt the airflow through the chassis and would result in the air not being directed out correctly? Not sure about this but kind of makes sense sort of like trying to squeeze too much liquid through too small a tube, its going to back up.

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY