CurtPalme.com Home Theater Forum

[WTS]

HI,

DOn't forget that you still need to have a 75R termination resistor for the Moome board, so I'd leave in R91/103. Now removing the coupling cap and the 39K is possible providing the DC offset coming from the Moome card is less than say a 1 0r 2mV. any dc offset will still need to be nulled out by U12 to get the BL to 0VDC.

And yes it will look better without the cap, you don't need to remove R90.

[Nashou66]

Well here is a pic of my modded 2005-03p Vim with the jupers in i used the center core of some silver plated audioquest wire i am using to make internal cables with, its really thick stuff so i think i am going to use something else...sorry got off track.
where should i cut traces on this vim if i even need to, going to test it after this post.




Athanasios

[9kids]

Wow looks like you have tried lots of mods. I will have to study this version of the VIM for a while to figure out the best places to cut and put in a relay.

In the mean time if you are going to use just the jumper you will need to lift R175 and I think D2. I think D2 is acting like a Diode clamp and you would be better with out it. You will want to keep R70 & R72 they are the 75ohm termination.

If you compare the internal video chain (since it comes from a DAC on the Control board). The external video chain could be done the same way since it is just coming from a DAC on the Moome board.

I could not get the jpg to show for some reason, Had to use a trick to put it inline.

[Nashou66]

There is some improvement for sure. here are some screen shots, not warmed up maybe 5-10 minutes on before screenies. 12 foot screen contrast 55 brightness 55.

I'm keeping it like this:

















Looks better than my last screens from same movie I think but scrren shots really dont show what i'm seeing on the screen.

I wonder if cutting any traces will help, just have to figure out which ones on my vim.

Athanasios

[9kids]

Glad it seem to be working. check my post just before your screen shots. I think lifting R175 will help even more.
The cap and R175 work togather to form the AC coupling. If you loose the cap then there is no need for R175.

[CRT_Ben]

Good Lord, I wish I understood what you guys are doing - I'd be petrified to go around cutting traces and bypassing parts like you guys are doing. More power to you! 8)

[9kids]

Anyone that wants to learn a little more about AC - DC coupling might want to read this APP note from MAXIM

http://www.maxim-ic.com/appnotes.cfm/an_pk/3303

[Nashou66]

[Nashou66]

You circled r70 in my pic , the signal goes through this and i think its need for termination reasons when it goes to internal video I think so i don't think this can be removed, is my line of thinking correct? I am no EE or techie either. just an average greek restaurant owner who loves this new hobby !!!!!!!! ok going to lift that 39k resistor first. then if i get gutsy and someone post i should, out goes D2 and r72.



Athanasios

[9kids]

I circled R70 and R72 in green, because they need to stay. They are the 75ohm termination. R175 should be lifted and you could try lifting D2.

[Nashou66]

I dont think D2 should go, if you follow the trace in the pic it connects to the 4.7 ohm resistor for the power supply to the op amp and also the decoupling cap, r93 and c14. these tie into Vee just as D2.

just watched some more and removing r175 and its respective siblings from the other channels works fine , this whole change has increased shadow detail and removed a little noise it seems, as these two go hand in hand and lowering noise is the ultimate goal for most of these mods. As Mike Parker says super high bandwith is not always the best for these circuits. the op amp i use isn't super duper high gigaherts like the ones Greg Eiesman always talks about and I think my lowley 2005-03p Vim looks pretty damn good along with all the other noise lowering mods i have done to other boards!! I cant wait till i finish the mods to it and take what I learned over to my 2035-03p vim. Thanks 9kids for thinking too much ! I was suppose to work on menu changes and now you got me all sidetracked!

Athanasios

[9kids]

Anybody got any ideas about how to select the right Relay for this?

[Nashou66]

I was looking at switches instead of a relay, would this work? But let me tell you, I dont think I'll ever go to BNC's anyways and I could easliy see the diference after removing the cap and one resistor then putting in the silver jumper. A relay would just add one more contact point. Unless you try your methode to route it into the existing relay, or use the relay that would be used for the quad decoder board. About those relays, do they work with each other or idependantly? I havnt read the service manual..maybe i should. It looks like the path way i came up with earlier in the thread wont work if they switch together, but if they are independant then you could cut the traces for the rgb signal just after the pins from the moome card and run from under the VIM board three wires for each color to the under side of the relay points but you would have to figure out which pins are for that quad decored board input. then have that corresponding output from the relay go directly to the op amp bypassing the cap and resitors.

Athanasios

[Nashou66]

Also now that I removed the one resitor(R175) that was perpendicular to the input signal i was thinking, there is always some noise in a signal...i know that the cap that was removed was a dc blocking cap and not used for removing any noise, so what if i use that pad from the removed resitor as a filter for removing some noise from the signal? it have to be the right value but i am not sure what frequency any noise would be with out scoping the input signal. Is there a general rule for this type of signal filter? I dont think it would harm the signal since its not in series like the removed cap. Does this make sence or is my theory completly wrong?

Athanasios

[Nashou66]

[WTS]

HI,

I would suggest you use either the Omron G6Z-1FE or the Panasonic TS-X series or the Fujitsu UM1 series.

[Nashou66]

maybe these then?
http://www.omron.com/ecb/products/pdf/en-g6z.pdf

I couldnt find the TS-X at neawark but this looks ok
http://pewa.panasonic.com/pcsd/product/rf/pdf_cat/rk.pdf

And i couldnt find the fujitsus at newark, i get most of my stuff from them

Athansios

[WTS]

try digikey

[9kids]

None of those seem to come in a DPDT. What do you think about this.

http://www.teledynerelays.com/electromechanical/rf100rf103.asp

The Can design and long leads would make it easy to mount in the small space just floating above the other componets.

[WTS]

Hmmm, I might some of those kicking around my parts bins.