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Marquee Modifications and Performance Enhancement
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Nashou66



Joined: 12 Jan 2007
Posts: 16167
Location: West Seneca NY


PostLink    Posted: Sun Sep 07, 2008 1:08 pm    Post subject: Reply with quote


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Well the reason I ask is on a MP modded VNB I have a pic of he relpaces two ferrinte beads with inducors, not sure what value, they are right next to pins 9 and 10 on the VNB crt socket.

Athanasios

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Arno P



Joined: 01 Jan 2007
Posts: 282
Location: The Netherlands


PostLink    Posted: Sun Sep 07, 2008 1:17 pm    Post subject: Reply with quote

Nashou66 wrote:
Well the reason I ask is on a MP modded VNB I have a pic of he relpaces two ferrinte beads with inducors, not sure what value, they are right next to pins 9 and 10 on the VNB crt socket.

Athanasios


Beads are a bit different than inductors in the EMC arena...beads do dissipate power and work like resistors instead of inductors

see:

http://www.murata.com/emc/knowhow/pdfs/te04ea-1/23to25e.pdf

(An example of bigger not being better Wink )

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Nashou66



Joined: 12 Jan 2007
Posts: 16167
Location: West Seneca NY


PostLink    Posted: Sun Sep 07, 2008 1:59 pm    Post subject: Reply with quote

yes i know this thats why i was wondering about the inductors Mike uses on the VNB.

Athanasios

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tse



Joined: 03 May 2006
Posts: 1014
Location: Sweatbucket, Fl.


PostLink    Posted: Sun Sep 07, 2008 4:49 pm    Post subject: Reply with quote

Caps are not always caps. There is a point where, as the frequency increases, the cap actually becomes an inductor.

Kemet has a neat software program that will plot the impedance vs frequency of some of their caps. It will even let you add series resistance/inductance (trace length). This is alot of fun to play with.

http://www.kemet.com/kemet/web/homepage/kechome.nsf/weben/kemsoft

Here are plots of 1206 size 100nF and 1nF caps. Notice the impedance of the 100nF begins to increase after 12MHz! The 1nF cap looks like a better decoupling cap up to 120MHz.

Scott



1nF_100nF.GIF
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draganm



Joined: 08 Mar 2006
Posts: 8744
Location: Colorado


PostLink    Posted: Sun Sep 14, 2008 4:09 pm    Post subject: Convergence stability Reply with quote

I have noticed over the last year a growing number of bad convergence boards. Of course the machines with these boards are averaging around 30K hours so this is not really a board problem but simply a maintenance issue. I also remember a lot of posts over the last couple of years where people are seeing some degree of drift with convergence and this isn't normal either.
Well the other day I decided to order replacement caps for convergence boards with the intent on replacing them regularly as a standard maintenance procedure, just like those 2 undertaed caps on the VNB's. Well to my surprise, I found the factory de-rated the big power caps on this board between 1995 and 1996 on up. the original spec was for a 400v rated cap, and after 95 they started using a smalled 250v cap. If you look on the newer boards you will see the foot print silk-screened on the board is for a much larger cap.
So my advice is re-cap thos C-boards for stable convergence.
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PaulB



Joined: 26 Oct 2007
Posts: 359
Location: Bonnie (but rainy) Scotland


PostLink    Posted: Sun Sep 14, 2008 5:13 pm    Post subject: Re: Convergence stability Reply with quote

draganm wrote:
the original spec was for a 400v rated cap, and after 95 they started using a smalled 250v cap. If you look on the newer boards you will see the foot print silk-screened on the board is for a much larger cap.
So my advice is re-cap thos C-boards for stable convergence.


Good spot! Just had a look and the board is exactly as you said. Convergence drift is one of my pet paranoia's about crt - anything I can do to avoid it is a high priority with me. I'm sure MP said (or inferred) that changing the caps on the Convergence board made little difference but I often wondered about this as changing caps elsewhere does (as we know) make a big difference! Presumably he simply meant on pq in which case it would indeed make no difference.

Anyway, the replacment caps, keep them at 10uf or worth a slight increase?

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Nashou66



Joined: 12 Jan 2007
Posts: 16167
Location: West Seneca NY


PostLink    Posted: Sun Sep 14, 2008 5:46 pm    Post subject: Re: Convergence stability Reply with quote

draganm wrote:
I have noticed over the last year a growing number of bad convergence boards. Of course the machines with these boards are averaging around 30K hours so this is not really a board problem but simply a maintenance issue. I also remember a lot of posts over the last couple of years where people are seeing some degree of drift with convergence and this isn't normal either.
Well the other day I decided to order replacement caps for convergence boards with the intent on replacing them regularly as a standard maintenance procedure, just like those 2 undertaed caps on the VNB's. Well to my surprise, I found the factory de-rated the big power caps on this board between 1995 and 1996 on up. the original spec was for a 400v rated cap, and after 95 they started using a smalled 250v cap. If you look on the newer boards you will see the foot print silk-screened on the board is for a much larger cap.
So my advice is re-cap thos C-boards for stable convergence.


Draganm you must be reading my mind or some how been watching me in my work shop!, The last few days i have been doing the VDM caps and the CVA caps, I up rated the voltage on all and used the Panasonic FM and FC series, I am going to do the write up but am waiting for the right resistors to come in first. I have already changed the caps on the VDM with FC and FM caps and these are a lot bigger so it took some creative work to fit them in there. I used 100v for all on that board i think. I also have all the caps for the CVA a I think I have the 10uf at 350 volt versions, i dont think thses are fc or fm as i dont think they go that high, I am at work now and going off memory.

Paul I think the caps wont help the convergence drift as much as the resistor change, the resitors you need should have a good temperature coeficient, meaning they are stable in a wide range of temp changes, that is what causes the drift as Mike parker states. he took a can of freeze spray and sprayed them on the resitors he mnetions and the grid moves a lot, i tried it on both the caps and resitors and when hitting thos resitors tthe grid moves.

Athanasios

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PaulB



Joined: 26 Oct 2007
Posts: 359
Location: Bonnie (but rainy) Scotland


PostLink    Posted: Sun Sep 14, 2008 6:15 pm    Post subject: Re: Convergence stability Reply with quote

Nashou66 wrote:



Paul I think the caps wont help the convergence drift as much as the resistor change, the resitors you need should have a good temperature coeficient, meaning they are stable in a wide range of temp changes, that is what causes the drift as Mike parker states. he took a can of freeze spray and sprayed them on the resitors he mnetions and the grid moves a lot, i tried it on both the caps and resitors and when hitting thos resitors tthe grid moves.

Athanasios



Blimey! An extreme test but one that proves the point! I knew that temperature played a part but hadn't realised just how much impact it could have.

I look forward to your 'How To' Athanasios. In particular the chosen type of resistors - I'm pretty sure you'll be well aware that many folks have found it fruitless trying to locate MP's recommended resistor for the mods on these boards. Even trying to work out exactly which resistors were the right ones to be used has been subject to much speculation. You've just uped the ante again by throwing in temperature considerations!

I had hoped you would visit this at some point in your maintenance/upgrade explorations - you've made my day (yet again) Thumbs Up

Brilliant, absolutely brilliant!

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mp20748



Joined: 12 Sep 2006
Posts: 5358
Location: Maryland

TV/Projector: 9500LC Ultra / Super 02 and 03 VIM


PostLink    Posted: Sun Sep 14, 2008 9:41 pm    Post subject: Reply with quote

I've not had much change from doing the caps on the convergence boards.

The changes I've noticed were from the fusible resistors (small) with the best changes and improvements being cleaning ( alcohol or other solvent) the heat sink isolator strip, and putting a slight coat of patroleum jelly on both sides of it.

Once done, that rear heatsink should run much hotter..
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Nashou66



Joined: 12 Jan 2007
Posts: 16167
Location: West Seneca NY


PostLink    Posted: Sun Sep 14, 2008 10:42 pm    Post subject: Reply with quote

Thanks for chiming in Mike ! It does look like they have better caps on the CVA then the VDM, and thanks for the tip on the petroleum jelly, i have heat sink compound I plan to use. I didnt notice befoer in your MPMT you put it on both sides thanks !

Paul these are the one's I ordered from mouser for the CVA the 1.2ohm half watt ones

http://www.mouser.com/Search/ProductDetail.aspx?qs=kUNaT%2fNjDRALo7EIfghHBw%3d%3d

Data sheet http://www.koaspeer.com/pdfs/res37.pdf

These are the 1/2 ohm half watt fusibles i used for both boards.

http://www.mouser.com/Search/ProductDetail.aspx?R=NFR25H0004707JA500virtualkey59420000virtualkey594-NFR25H0004707JA5

Data Sheet: http://www.mouser.com/catalog/specsheets/Vishay%20Fusible%20Resistors%20nfr25.pdf


Athanasios

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draganm



Joined: 08 Mar 2006
Posts: 8744
Location: Colorado


PostLink    Posted: Mon Sep 15, 2008 3:38 am    Post subject: Reply with quote

ok, so maybe the drifting and board failures are not related. It seems like there's been more failures lately of the transistors on the C board and it causes one of the 2 amps on each channel to fail. I assumed it was leaky caps contributing to this?
Anyway, here's a pic of the 95 vs. 96 boards, newer board in the back



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PaulB



Joined: 26 Oct 2007
Posts: 359
Location: Bonnie (but rainy) Scotland


PostLink    Posted: Mon Sep 15, 2008 5:52 am    Post subject: Reply with quote

draganm wrote:
Anyway, here's a pic of the 95 vs. 96 boards, newer board in the back


Interesting, I suppose they just lowered the the value (capacitance and voltage) of the parts to what they could get away with rather than what was actually needed. No different from a lot of other business companies I suppose.

Thanks for raising this draganm, its shed much needed light on an area often ignored.

These last few posts have been snippets of excellence, kudos to MP and Athanasios!

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draganm



Joined: 08 Mar 2006
Posts: 8744
Location: Colorado


PostLink    Posted: Mon Sep 15, 2008 3:55 pm    Post subject: Reply with quote

PaulB wrote:
Interesting, I suppose they just lowered the the value (capacitance and voltage) of the parts to what they could get away with rather than what was actually needed. No different from a lot of other business companies I suppose.!
the capacitance stayed the same at 10Uf, the voltage rating dropped though, probably to save money like you mentioned. At an avergae of 30k hours it's probbly a good idea to replace them anyway. the caps are always the Achilles heel of any electronics device.

PaulB wrote:
Thanks for raising this draganm, its shed much needed light on an area often ignored.
These last few posts have been snippets of excellence, kudos to MP and Athanasios!
there's a lot of stuff in this thread I want to try but time is such a luxury in short supply. Luckilly I have an MP video chain in my machine for many years now, even though they're an older version they still blow away a stock machine.
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PaulB



Joined: 26 Oct 2007
Posts: 359
Location: Bonnie (but rainy) Scotland


PostLink    Posted: Mon Sep 15, 2008 9:08 pm    Post subject: Reply with quote

Odd question of the day - what size soldering tip you guys using for these mods?

I generally use a 1mm tip but thinking of going to 0.5mm, just wondering.

For some odd reason I've been finding it difficult to de-solder stuff with the new tip I'm using and wondered if a change in size might help (may just be a bad tip as the problems only started when I put it on a couple months back and when I just soldered something just now it didn't go quite as well as it should and I remembered that I'd had problems with this tip before. I've got spares but wondered what others are using size-wise.

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Nashou66



Joined: 12 Jan 2007
Posts: 16167
Location: West Seneca NY


PostLink    Posted: Mon Sep 15, 2008 9:21 pm    Post subject: Reply with quote

paul if you plan on doing more work on the boards i'd get a station, unless you have one already, i have an Aoyue 968 and love it I also got a tweezer iron that makes removal of thos SMT ceramic chips a breeze! And the hot air gun is great for removing the chips, especially if the ic popper tool they give you fitts under the chip pins, you slide it under, heat up the chip with the gun and it pops up! awesome!!!!



And the tweezers



I just got the 1/2 ohm fusible resistors and am in my shop as I type working on the VDM. post to follow soon.
On aside note I did the rework of a VNB to accept a sony pinout Hybrid tube, so now we can use sony tubes too, i am looking for a few sets of VNB's so i have both on hand !

Athanasios

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Don't blame your underwear for your crooked ass~ unknown Greek philosopher


"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan

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PaulB



Joined: 26 Oct 2007
Posts: 359
Location: Bonnie (but rainy) Scotland


PostLink    Posted: Mon Sep 15, 2008 9:44 pm    Post subject: Reply with quote

WTF!!!!???

I've got myself a decent Soldering Station but I've never heard of Soldering Tweezers or IC Poppers! No wonder you whizz through these mods Shocked I'm using stone age tools whilst you are using precision instruments, FFS.

I like the idea of the tweezers and the popper - I'll try to get some that will fit my station. The soldering iron plug looks the same, a 4 pin screw-on thing.

Talk about making life more difficult for myself, jeezo Sad

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Nashou66



Joined: 12 Jan 2007
Posts: 16167
Location: West Seneca NY


PostLink    Posted: Mon Sep 15, 2008 9:49 pm    Post subject: Reply with quote

Mine has 5 pins, yeah when Andre asked for me to do his CLM i though damn thats a lot of work!!!! So i found this fairly cheap, its really nice for the amount of cash.

Athanasios

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Don't blame your underwear for your crooked ass~ unknown Greek philosopher


"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan

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PaulB



Joined: 26 Oct 2007
Posts: 359
Location: Bonnie (but rainy) Scotland


PostLink    Posted: Mon Sep 15, 2008 9:59 pm    Post subject: Reply with quote

5 pin, ok, looks like I need the whole unit then (tweezers and its own station), worth it for the hassle it will save though!

Glad I asked the question now, thanks Athanasios Thumbs Up

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Nashou66



Joined: 12 Jan 2007
Posts: 16167
Location: West Seneca NY


PostLink    Posted: Thu Sep 18, 2008 2:38 am    Post subject: Vertical Deflection Modual Resistor and capacitor upgrade Reply with quote

Next we are going to work on the two boards on the back heat sink the
Vertical Deflection module and the Convergence Amp. These are sometimes
connected together with a few bridges of the pcb material. The extra boards
I used for this installment were already cut so working on them was made
easier. If you want to make it easy you can do the same with a sharp blade.
One thing is its too hard to test these boards as we go so double check your
work as we will do it all at once then install.

here is pic of the two boards on the heat sink:



The resistor replacement was first talked about in the Mike Parker Marquee
maintenance thread on AVS. It was a "nugget" he revealed to us ! thanks Mike ! Smile
I also decided to change all the caps as you know they age and there are better caps out
there to use.

The resitors are something that many people were confused about so I will list
the ones i ordered from Mouser.

For R720,721,820,821,920,921:
.47ohm 1/2 watt fusible resistor from Vishay 594-NFR25H0004707JA5

there are 12 more of these on the CVA also but that is later.

for R5 and R6 Mike says to use the same but My board had 2.2 ohms and I think the .5 ohms
would be a bit too low, and the service manual lists 1 ohms, hmm what to do?
I decided to use the 1 ohms

1ohm 1/2 watt Vishay 594-NFR25H0001008JA5

I also decided to replace the resitors on the +/- 5 volt rail as these too are the "mickey Mouse"
resistors Mike complains about.

These are 2.2 ohm fusibles Vishay 594-NFR25H0002208JA5

I didnt have the resistors in yet and did the caps first, but do the resistors first as
I think it be easier to get to them with the smaller old caps in still.

Ok now removing the boards. First you need to take the heat sink off the PJ, to do
this you need to take off the sides to get to the hinge screws, you may also need
to take of the metal side panels as well, When replacing a faulty board a year ago I
was able to squeez a screw driver in with out removing it.
When you get it off the PJ you need to remove the transistor clamps that hold them
tight against the heat sink. I used my pry tool for soldering.

First pull toward the back of the heat sink off the transistors



Clamp moved towards back of heat sink



Now pry up clamp off heat sink




Once all clamps are off mark location of boards to make it easy to line up to
wire harness to mother board

Mark board location




Now slide out board, mine was already cut from the CVA



Board removed with hot desoldering iron ready!!



First Replace the resistors near the caps, these are R720,721,820,821,920,921.

Resistors 720 and 721 removed



Raise the new resistors up off the PCB



I raised the second one higher like the origianals were, one high one lower



R820 and 821 notice how much bigger the caps wil be compared to the old ones !!



Now resistors R5,6,92,and 94

R5 and R6 in place



And R92 and R94



Next will be the caps, too tired to finish the rest of the write up... Embarassed Zzzzzzzzz


Athansios

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Don't blame your underwear for your crooked ass~ unknown Greek philosopher


"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan

One Smart Dog!!!

Marquee High Performance Bellows now shipping!!
Marquee Modifications and Performance Enhancement
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Last edited by Nashou66 on Sat Jan 01, 2011 3:03 am; edited 3 times in total
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PaulB



Joined: 26 Oct 2007
Posts: 359
Location: Bonnie (but rainy) Scotland


PostLink    Posted: Thu Sep 18, 2008 5:16 am    Post subject: Reply with quote

A quickie as I'm just off to worl Shocked

My board R721 for example has the piggy-backed resistors - replace with a single or replace with piggy-backed? I think MP recommended piggy-backed but don't have time to check, late already.........! Outta here.

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