CurtPalme.com Home Theater Forum

[1031]

[Nashou66]

[1031]

[Nashou66]

Ok I'll forget thinking about replacing that chip then.

Athanasios

[Nashou66]

[1031]

Those inductors should work ok instead of 4.7 ohm resistors. That 1206 size ferritebead i foundet at some op-amps datasheet, they had evalution board for their chip and on that evalutionboard they recommendet to use those beads. But its important if you replace those 4.7ohm resistors with inductor/beads to add more capacitance after bead/inductor. I bet, if you just replace 4.7ohm with those inductors and leave just that 100nf cap after that there will more troubles then..But if you put more capacitance after inductor, like 4.7-15uF+100nF+10Nf etc.. then you get much better performance.

[Nashou66]

I actually have a 4.7uf,100nf tant and a 100pf silver mica. I plan to use a 10nf across the +/- 5v pins of the el5166. I think would be a good way to do it also.

Athanasios

[1031]

Sounds good.But that cap across vcc/vdd pins souds little too small.
If you look datasheet from LHM6702 you found that they recommendet use 100nF cap across vcc/vdd pins

[Nashou66]

Yes, i have read that, but it seems many differnet manufactures have different ideas for their chips. I don't think Intersil recommends any caps across those pins. i was just going on this from the old archive AVS thread where Mcpherv used 10nf caps on the voltage pins for most of the op amps including the TL071's. I think he said they are there just to help out with drops in power and less as a noise supressor. First i need to add those inductors and then the BFR93 chips you sugested.

EDIT Jarmo just added those chip inductors and the BFT93 chips, all looks well so far.

Athanasios

[PaulB]

Regarding the VNB's, whats the final thinking with regards C29 and C30 ? Are we still looking at replacing the originals with the 4.7 Tants plus a Mica or are the originals staying in place but with a Mica added ?

I got a bit confused and can't figure out what the outcome was of the conversations between you guys (not sure if some of the suggested changes referred to the VIM or the VNB's).

Brilliant thread guys, again, my thanks for your hard work and willingness to share

Paul

[Nashou66]

Ok this is what would be easiest to do, remove the originals and replace with a sufrace mount ceramic same value this way you just add a 4.7uf tant on top for easy placement then the 100pf mica on top of that. do what is in the pics but underneath the 4.7's i have put that 100nf ceramic or other type of 100nf cap. this is for the VNB, the VIM will be soon as i am experimenting still.

Athanasios

[PaulB]

Ok, I understand. Like a sandwich!

Top...
Mica Cap
4.7 Tant
Ceramic Cap
....Bottom

This the sort of ceramic - http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=478-1480-1-ND

Stupid question of the day - The Mica, its soldered to the ceramic or soldered to the ceramic and the Tant? Thinking it through, maybe doesn't matter which as its all connected anyway?

As an after thought, couldn't you just leave the originals in place and solder a piece of wire to them (vertically, attached to the solder at the ends) to attach the tant to? Be easier than removing them I suspect.

Plenty of unused cut-off capacitor legs - I knew they'd come in handy!
Paul

[Nashou66]

I always thought of that but from a performance point its not recommended , You could use any ceramic taken from other boards, eventually on the VIM those
100nf de coupling caps we';ll replace with 100nf/.01uf tants, so you could take those now if you wanted too.

Athanasios

[PaulB]

Ok, understood. Thanks for the info and clarification Athanasios, much appreciated.

All VNB's now modded as per your insrtuctions (apart from C29 & C30 on each, just need to get hold of the ceramics but I think I'll buy them for now - don't want to cripple the VIM just yet!)

Also C2, I had a look but other than some markings (RA5 I think), I can't tell what it's values are. I have a schematic for the VNB's, I'll have a look at that.

Hardest part was removing the OpAmps at U4, got there in the end though. Bought myself a Soldering Station, works far better than a normal iron - highly recommended!

Given that I'd never touched a soldering iron until very recently I'm quite proud of what I've acheived so far. If anyone else is thinking about it but has doubts as to their soldering ability, give it a go ! Just get a good tempreture contolled soldering station and (if possible) get one that has pre-tinned tips - works a treat! I found that tinning the tips was a real challange and totally prevented me from soldering anything, but once I got hold of some pre-tinned ones soldering suddenly became real easy (well, easy-ish).

Paul

[Nashou66]

[1031]

[Nashou66]

I haven't given it a good look since this weekend was My Easter ( Greek Orthodox). But from the 15 minutes i did look the picture seamed very good. if their was an improvement is was just enough to notice something but not sure what . I will put up some pattersn and watch some of the video on my DVE Blu ray disc to evaluate and let you know. I Also want to start doing what i did to the 2003-03p VIM to the 20035-02P VIM and take pics for one on my instalments here on this thread. I'll add those to the list of Mods.

Athanasios

PS i still need to use the scope more,wish i had extender card for the marquee.

[1031]

[1031]

Here is close up how i did "cheap extender card"

[Nashou66]

I bought euro conectors as i was going to make my own with cable but they sent my the two row conecxtor instaed of the three row for the vim. I was going to use ribon cable but then realized its hard to reach in there to conect it to the back plane. I was also thinking of just using some of those PCB,s they have at Radio shack where you paint the trace and then use the acid to wash away the rest of the copper. Would that work?
That would also be a nice post to add here with detailed instruction if i get the time.


Athanasios