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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Tue Apr 27, 2010 2:48 am Post subject: It pains me to post this (modding projectors..) |
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..especially since the customer is a forum member and a repeat customer, but I do need to throw this out there to warn others.
I spent the entire, and I mean ENTIRE afternoon working on a Marquee convergence board that had been modded. The fault was on red H convergence control. Simple enough, I'd repaired a bunch of those, although the odd board was always a pain to repair.
The customer (I believe, haven't had confirmation yet) modded the board by replacing the capacitors and a bunch of the fusible resistors. All soldering was well done, the caps were in correctly, etc. After checking a bunch of parts, I found a leaky transistor, so I replaced it. I was rewarded with a big puff of smoke, and I quickly unplugged the set. After seeing one of the replaced fusistors glow red hot right before I pulled the power cord, I realized that the 1/8 watt fusistors had been replaced with 1 watt flameproof resistors. Now, a fusistor is exactly that, a resistor that also acts as a fuse. It's designed to blow open in case of an overload, and putting a flameproof 1 watt resistor in place of a fusistor is like putting a nail in a fuse holder. You've just completely eliminated that fuse as a safety device. Considering a 1 watt resistor is 8 X the size of 1/8 watt, you can see the problem. I sure did with the puff of smoke that occurred. 
So, I then spent the last 90 minutes replacing over a dozen parts that smoked. Output and driver transistors, and all fusistors in that one channel.
So.. now the board works again. There's no way of telling, but it's quite possible that the original fault, and most certainly the subsequent smoke show was caused by this mod, and the fact that the wrong parts were put in.
Just FYI.
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greg_mitch
Joined: 03 May 2006
Posts: 5320
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| Posted: Tue Apr 27, 2010 2:51 am Post subject: |
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Why would I leave them in there if they just keep blowing? 
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Tue Apr 27, 2010 2:53 am Post subject: |
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BTW, just swapped some emails with Dragan, and his mods and components used are fine if anyone is wondering.
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MikeEby
Joined: 24 Jun 2007
Posts: 5237
Location: Osceola, Indiana
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| Posted: Tue Apr 27, 2010 2:55 am Post subject: |
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What would be gained by modding a convergence board? Either the set is converged or its not. Neck board or video signal board I can see, I just don't see the point of shotgunning parts.
Mike
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Tue Apr 27, 2010 2:59 am Post subject: Re: It pains me to post this (modding projectors..) |
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| Curt Palme wrote: | .. After seeing one of the replaced fusistors glow red hot right before I pulled the power cord, I realized that the 1/8 watt fusistors had been replaced with 1 watt flameproof resistors. Now, a fusistor is exactly that, a resistor that also acts as a fuse. It's designed to blow open in case of an overload, and putting a flameproof 1 watt resistor in place of a fusistor is like putting a nail in a fuse holder. You've just completely eliminated that fuse as a safety device. Considering a 1 watt resistor is 8 X the size of 1/8 watt, you can see the problem. I sure did with the puff of smoke that occurred.
Just FYI. |
In case anyone is wondering, and since Curt wasn't kind enough to clarify  , I never touched this board.
One small correction though, the factory schematic calls for a 1/2 watt fusibles. Obviously, the 1 watt flameproof that someone installed here (I'm assuming wire-wound or metal film) is a huge mistake. If you plan to work on your boards and want to replace these , the correct part is Vishay NFR25H0004707JA500 .
thank you for your support. 
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Tue Apr 27, 2010 2:59 am Post subject: |
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| Curt Palme wrote: | | BTW, just swapped some emails with Dragan, and his mods and components used are fine if anyone is wondering. |
thank you Curt
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Tue Apr 27, 2010 3:06 am Post subject: |
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| MikeEby wrote: | What would be gained by modding a convergence board? Either the set is converged or its not. Neck board or video signal board I can see, I just don't see the point of shotgunning parts.
Mike |
There's two sides to this argument, hashed out here and over at avs for years.
I say, if it ain't broke, don't fix it. There are usually a bunch of mods that I do to my projectors of replacing parts that commonly fail, and where possible I change to higher quality/higher spec parts.
Then people like Kal have had noticeable improvements by changing all caps on his Barco 800 SMPS, and he says the thing was much more stable after he did that.
No question it's a nice feeling knowing that you have 50-75 new caps in your projector/other electronic device. It's been tempting to do it to my own 12,000 hour chassis completely stock 9500 that has some convergence drifting, so I wanted to try to shotgun the set just for my own satisfaction to see if changing 50+ caps to see if it does anything. I just haven't gotten to it yet.
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Tue Apr 27, 2010 3:12 am Post subject: |
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| MikeEby wrote: | What would be gained by modding a convergence board?
Mike |
Mike what a lot of us were seeing is that the Conv. on a typical mid/late 90's marquee just wasn't staying put. Even if you waited till the machine was fully warmed up, then converged it, the next time you were watching with the set warmed up again it would be out, quite a bit too.
Personally I replace 66 parts on this board and it seems to help a lot. Of course using the correct parts is crucial. If anyone is interested all the correct parts are listed in the Marquee maintenance thread. If you decide to use different resistors you experiment at your own risk.
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Tue Apr 27, 2010 3:14 am Post subject: |
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| Curt Palme wrote: | | No question it's a nice feeling knowing that you have 50-75 new caps in your projector/other electronic device. It's been tempting to do it to my own 12,000 hour chassis completely stock 9500 that has some convergence drifting, so I wanted to try to shotgun the set just for my own satisfaction to see if changing 50+ caps to see if it does anything. I just haven't gotten to it yet. |
Curt for you I would be willing to donate a kit in exchange for an honest evaluation of what you see before/after. I have to warn you though, it not 75 parts but closer to 200 
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Apr 27, 2010 3:31 am Post subject: |
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Those damn Marquees. We should see if we can get VDC to start making Ampros again. 
They just keep on running, lol.
What do you say Chip? Are you in?
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Apr 27, 2010 3:33 am Post subject: |
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| draganm wrote: | | Curt Palme wrote: | | No question it's a nice feeling knowing that you have 50-75 new caps in your projector/other electronic device. It's been tempting to do it to my own 12,000 hour chassis completely stock 9500 that has some convergence drifting, so I wanted to try to shotgun the set just for my own satisfaction to see if changing 50+ caps to see if it does anything. I just haven't gotten to it yet. |
Curt for you I would be willing to donate a kit in exchange for an honest evaluation of what you see before/after. I have to warn you though, it not 75 parts but closer to 200 |
Hell. If I had to replace 200 parts on just one board to keep my projector running I would tie it to a rope and the other end of the rope to my boat. Then I'd get some good use out of it.
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Tue Apr 27, 2010 3:35 am Post subject: |
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You do need to replace the big 47uf cap on a PG Deflection board, with a 470uf cap.
That's fixing a mistake, not a "mod".
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kal
Forum Administrator
Joined: 06 Mar 2006
Posts: 18114
Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
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| Posted: Tue Apr 27, 2010 3:44 am Post subject: |
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| Curt Palme wrote: | | Then people like Kal have had noticeable improvements by changing all caps on his Barco 800 SMPS, and he says the thing was much more stable after he did that. |
The important thing to note is that my old Barco 800 in which I replaced all the power supply caps had almost 30,000 hours on it. The convergence on it took a good hour before it became stable and it would never stabilize in the exact same spot which meant I'd often have to do a quick 20 second static convergence 'tweak' after warming up before I could watch it. After replacing those caps it would stabilize after 5-10 mins or so and always fall into position with no tweaks required.
But like Curt said, unless you really know what you're doing, don't attempt it.
Kal
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Last edited by kal on Tue Apr 27, 2010 3:46 am; edited 1 time in total
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Spanky Ham
Joined: 22 Mar 2006
Posts: 5643
Location: Comedy Central
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| Posted: Tue Apr 27, 2010 3:45 am Post subject: |
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| macgyver655 wrote: | Those damn Marquees. We should see if we can get VDC to start making Ampros again.
They just keep on running, lol.
What do you say Chip? Are you in? |
You were just at VDC. Didn't you see the 3600s or did they stop making them?
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Apr 27, 2010 3:49 am Post subject: |
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| Spanky Ham wrote: | | macgyver655 wrote: | Those damn Marquees. We should see if we can get VDC to start making Ampros again.
They just keep on running, lol.
What do you say Chip? Are you in? |
You were just at VDC. Didn't you see the 3600s or did they stop making them? |
No, I didn't see them, damn-it. We didn't talk about whether they were still making them or not. I didn't have a lot of time.
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dvh99
Joined: 25 Dec 2009
Posts: 2158
Location: nederland
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| Posted: Tue Apr 27, 2010 3:54 am Post subject: |
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the drifting was the 1 thing that drove me crazy.
after replacing the resostors and caps it settles after 15 mins and is spot on.
i havent touched the pj for 3 months and the convergence is still spot on.
i must say that i have replaced a whole lot more than just the convergence resistors and caps but i think the convergence board recap will be enough.
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Spanky Ham
Joined: 22 Mar 2006
Posts: 5643
Location: Comedy Central
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| Posted: Tue Apr 27, 2010 4:05 am Post subject: |
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| macgyver655 wrote: | | Spanky Ham wrote: | | macgyver655 wrote: | Those damn Marquees. We should see if we can get VDC to start making Ampros again.
They just keep on running, lol.
What do you say Chip? Are you in? |
You were just at VDC. Didn't you see the 3600s or did they stop making them? |
No, I didn't see them, damn-it. We didn't talk about whether they were still making them or not. I didn't have a lot of time. |
To bad. Here you go.
http://img202.imageshack.us/img202/4002/vdc1custom.jpg
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AnalogRocks
Forum Moderator
Joined: 08 Mar 2006
Posts: 26706
Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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| Posted: Tue Apr 27, 2010 4:57 am Post subject: |
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| Spanky Ham wrote: |
To bad. Here you go.
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Cool! AmPro Porn!
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Tue Apr 27, 2010 5:07 am Post subject: |
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| macgyver655 wrote: | | Hell. If I had to replace 200 parts on just one board to keep my projector running I would tie it to a rope and the other end of the rope to my boat. Then I'd get some good use out of it. |
LOL, well on one said anyone with a Quee HAD to replace anything. It's like a tune up for a car, you don't need to replace the fart plugs or air filter to keep driving but the car might run a little better if you do.
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Sparky015
Joined: 12 May 2009
Posts: 1185
Location: Cleveland / Akron, OH
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| Posted: Tue Apr 27, 2010 1:08 pm Post subject: |
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I just like the quees in the background.
I'm not sure Marquee owners can say much about Ampros after Mike's recent thread where he called Eureka on the best magetics setup for a Quee is a what was always done on an Ampro.
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