CurtPalme.com Home Theater Forum

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

Jorge what would it be for 1056x800p@72hz?

Also did can you list which caps are switched in? Just use the red channel locations of caps.

Nashou

mp20748 · Posted: Wed Mar 25, 2015 12:10 pm Post subject:

Man, the contributions to this tread has been great stuff... stay with it fellas.. Thumbs Up

barclay66 · Posted: Wed Mar 25, 2015 12:22 pm Post subject:

Hi,

let's do the complete list for further reference:

_____________R____G____B___________R____G____B_______
Band-SW0 -> C117/C217/C317 (33nF) + C118/C218/C318 (22nF) -> Active when H-Freq above ~85KHz
Band-SW2 -> C117/C217/C317 (33nF) + C119/C219/C319 (68nF) -> Active when H-Freq above 60KHz and below ~85KHz
Band-SW4 -> C117/C217/C317 (33nF) + C120/C220/C320 (2.2µF) -> Active when H-Freq below 60KHz

I cannot tell which switch will be active at 1056x800p@72hz as this resolution is not available on my test pattern generator. But You can read the current H-Frequency when pressing the <*> Button on the Marquee remote twice. I believe it will be somewhere in the 60KHz area. So it could be Band-SW2 or Band-SW4.

I can make a drawing of my adapter, if necessary. Then You can try it out too...

Regards,
barclay66

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

barclay66 · Posted: Wed Mar 25, 2015 12:49 pm Post subject:

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

Ok one more question.

in the pic of your circuit board with SWB 4 light on means that it is pulling the 2.2 uf cap out of the circuit correct?

barclay66 · Posted: Wed Mar 25, 2015 1:35 pm Post subject:

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

I sent you an email I think about the formula for the picking the correct cap with regards to frequency. Do you have it?

Athanasios

barclay66 · Posted: Wed Mar 25, 2015 2:15 pm Post subject:

Hi,

I think You were looking for this thread: http://www.curtpalme.com/forum/viewtopic.php?p=182553
But there's no formula over there.
Normally the formula is 2*pi*F= 1/sqrt(L*C) Where F=frequency / L=inductor value / C=capacitor value.
This is a good online calculator: http://www.1728.org/resfreq.htm
Select "Solve for Capacitance", enter the values (watch for the correct units) and press "Calculate".

One interesting thing: Previously in this thread, cmjohnson mentioned the dynamic focus coils having 5µH. Therefore I calculated with this value. When looking at Scott's simulation in the other thread I can see a value of 41µH! The difference has a big impact:

64KHz with 5µH -> 1.23 µF ideal capacitor
64KHz with 41µF -> 0.150 µF = 150nF ideal capacitor

At this point it would make a lot of sense measuring the focus coils (which I will do this evening)...

Regards,
barclay66

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

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

So my frequency was 61.14,
uH is 45.6,
and cap value came to 148.60 nf according to the calculator.

So I would need for that red coil a 148.60-33 =115.6 nf cap instead of the 68nf cap?

Nashou

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

Wait somethings not right I think.

If i use the micro henry button( i just used the henry button before) and hertz button aI get 1.4860e+8 Nanofarad

that is 148600000 nf ?

That is not right....... right?

barclay66 · Posted: Wed Mar 25, 2015 3:16 pm Post subject:

barclay66 · Posted: Wed Mar 25, 2015 3:19 pm Post subject:

Hi,

These are the right values:

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

So it seams changing the value for me would really make sense since it suck a large difference from 111nf to 149 nf.

Nashou

barclay66 · Posted: Wed Mar 25, 2015 5:12 pm Post subject:

Hi,

please have in mind that the real world is different to any calculation/simulation (just as Scott said).
My gut feeling is that the real values should be a little lower (additional capacitance coming from PCB traces, wires etc. Other factors like stray inductance, DC resistance of the coil etc.). You could try with 82nF or 100nF as a replacement for the 68nF cap first.

You will have to verify the results. There are two options:

- Scoping the amp outputs. Frankly I don't know how the 'ideal' signal should look like. You may have to ask Scott as he might know. The information from the other thread is not enough as it is a simulation only.

- Measuring the temperature. The FGM should run cooler the more efficient the amps work.

Regards,
barclay66

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

CSX · Joined: 11 Feb 2015 Posts: 142 Location: Ohio

barclay66 · Posted: Wed Mar 25, 2015 9:07 pm Post subject:

Hi,

This is the display circuit mentioned earlier. Please feel free to ask questions if there's anything unclear...

I don't like it but it has to be added: I assume no responsability if something goes wrong with Your machine by building and connecting this circuit. It has worked for me and can't possibly do any harm if built and installed correctly. Always make sure that none of the board's parts makes contact with metal parts of the chassis and take care for Your own safety too!

Regards,
barclay66

CSX · Joined: 11 Feb 2015 Posts: 142 Location: Ohio

I just finished the addition of the inductors.
Seriously, the difference was night and day.
-No capacitors changed yet, only the addition of 4 total inductors.
->I'm still watching this thread to possibly gear the capacitors for my typical usage.

I'd like to do the HVPS, but can't find a solid list of the values / types. I can match the values by color, but really want to ensure that I am ordering the correct value / material from Mouser. Would you happen to have this info handy, Nashou?

And again, this mod really does make a huge impact for the small amount of effort you have to exert to complete it.