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Discussion Starter · #1 ·
Eeek, I turned on the PJ tonight and it was fine. Returned to it an hour later and I have this high pitched sound coming from it. My father who happens to be visiting can't hear it, but I can. I tried switching inputs and it didn't change at all. I then tried turning it off with the remote, and that didn't change it. I then pushed the power button on the NEC GP-3000. And it changed in pitch (lowered) and was gone. Left it for a minute, pushed the power button on the unit and it was there again. Pushed the remote power and the PJ continued on, still with this whine.


Why oh why do I think this is the power supply? Heeeeelp!
 

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Taylor,

It does sound like it, get a hold of Mike Parker, he repairs these. Theres a chip that usually fails in these and cant be found to replace, try to save that component if you can. After you shut it off the caps have to drain, thats why it changed pitch then was gone. See what he says about this, you might be able to save it by replacing some capacitors before it blows the chip. Doug
 

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Discussion Starter · #3 ·
Curt got back to me last night and suggested I start swapping boards starting with the Deflection (DEF) board. I just did that and pushed the chassis power back on, the whine/sound/whistle is still there. I haven't pushed the power on the remote, I see no reason to put more load on the power supply with that sound still there.


Any ideas on to the next board I should try swapping? (unfortunately I don't have a power supply to swap in or this whole thing'd be moot. :)


Doug: I'll try hunting down an email address for Mike Parker, thanks.
 

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I'm going back to the old days here, but I think high-pitched whine or squeal is usually a cracked, broken, or loose high-voltage flyback transformer. It's weird, though that it didn't go away when you shut the projector down with the remote, but did go away when you used the power switch.


The flyback transformer shouldn't be hot unless the projector was on. Anybody have any other ideers?


SC
 

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Taylor,

The following caps should be replaced in the 3000 power supply:


C46, C42, C20, C19, C18, C13.


They are located around IC02 (PJX-01). That ic will run hotter if C13 becomes leaky, if that happens the standby power supply voltage for IC02 would become unstable and oscillation is possible.


I'm not saying that this is the case with your set, but I would change the listed capacitors even if the set was working properly, especially C13.
 

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Mike,

I do know that the GP power supply has its problems, mainly because we cant get the darn chip to give security that it wont become a boat anchor. I have no less then 10 of these just hoping we can find them.


Sure appreciate the time you have spent helping to save that part, in this case its a no lose situation in my opinion, do you see the caps being the reason for the chip failure? Anything other then the age of these that could be considered preventative maintance. I always tell people to use a dedicated circuit to the projector, I do find less problems with those running one.


I have some that have been running for years without a problem, four of these have been retubed 3 times. Doug
 

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Doug,

the ones that I have looked at that had the bad chip all had a leaky C13 capacitor. I had once replaced the chip from another supply and the chip was running hot, so I immediately measured B+ to the chip and found it to be higher than the manual, plus it had noise (AC) on it. After changing C13 the chip cooled down and ran at a comfortable temp.


C13 is in the standby power supply circuit, the other caps are on the chip circuit. This circuit is on at all times when the projector is plugged in.


If there is a reasonable demand for this chip - I have the diagram, we could try and reproduce it:

http://216.239.51.100/search?q=cache...+modules&hl=en
 

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Discussion Starter · #8 ·
Okay, I replaced every one of those caps with the exact UF and V settings as well as max temperature settings (105 celcius). The power supply, by itself, still emits a whine that only I can hear (no one else in the house can apparently hear it). I temporarily hooked it up to the PJ and fired it up and it sounds the same as it did.


With my ear to the power suplly (top off) it sounds like the whine could be coming from one of the very large caps, the 200V 1500uF ones. But I do not know if it's just the sound bouncing off the little metal bracket there...


I also disconnected the smaller board from the main board and the sound was still there.


So... any thoughts? Anyone selling a GP power supply? *sob*


Tempted to just put it back together and live with it, but if Ican fix it, I'd like to.
 

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Discussion Starter · #9 ·
Okay so I tried changing the larger capacitors (200V 1500uF) and the sound was still there, so I put the old larger ones back in. Just watching the set now kind of hoping the problem goes away. Oh I also tested the PS connector board connections as per the troubleshooting part of the manual on Power Supplies and with the exception on IA Pin-1, everything was preet close to it's apprx values. IA Pin-1 was reading 35V where the manual says it should be approx. 40V. Everything else was within 2-3V.
 

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Does anyone have a schematic of this power supply that I could examine?

The whine could be comming from the switching transformer on the power supply. It MAY be that the varnish that quiets the windings in the transformer is comming a bit loose. However, replacing said Caps above is a definite must. I am still hoping Doug will let me have a bad power supply to study, I have a few very well connected friends in the chip industry. Really hoping that these can be resurrected. BTW, for what it's worth, I usually glue small heatsinks to IC's that run hot on my personal stuff. Seems to help in the long run. Just an idea.


Marc
 

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Marc,

Ill try to get overthere soon, had to run out to Infocom and I wasnt planning to do that this year. Ill also bring you a power supply to look over and a schematic. Maybe you can come up with a solution, when I couldnt find the parts I put it on hold, I know Mike tried also. I didnt have the time back then to look deeper. Doug
 

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Discussion Starter · #12 ·
Marc: Well seeing as how I've replaced those Caps and the sound is still there, perhaps you are right...


Anyone have the schematics for the board? I have just about every page of the Users and Service manuals EXCEPT for the PS Circuit Board Diagrams, Soldier Side and Component Side diagrams. (Figures, in 1000 pages, those are the ones I'm missing). If I take a photo of the supply can someone point out the transformer I should try swapping out?


-Taylor
 

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Doug,

I have a lot of info on the internal workings of that chip. I sent Marc a PM, there are two ways to solve this problem. Check you PM!
 

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Discussion Starter · #14 ·
Hellooooo? Are we out of suggestions here?


BTW, when looking at the caps I took off, I can't tell if they're leaky or not.


Some of them exhibited what looked like a hardened liquid on the very bottom of the cap, nothing really on the PCB that I saw. Is that what a leaky cap looks like?


C13 looked absolutely fine, looked pristine. The larger ones (200V 1500uF) looked pristine underneath too). What about these monolythic caps and these wide burgundy ones? Should I be looking at replacing those too? I don't see a rating on them anywhere.


This Power Supply looks like it's been worked on before as the connectors that go to the Power Dist Board (one between Blue and Green lenses) are not like any other connector in the whole system and have blue pen wirtten on them to tell you which one goes where. (i.e. IA, IB, IC, ID)


Should I just mark down all the caps ratings and replace them all?


Anyone have a photo of these caps from an untouched board, perhaps whomever worked on this supply prior to me had made a mistake and put the wrong caps in or something.


My manual is missing the whole PS section of the schematics. Pages 28 to 33. Anyone have those that they could scan and email or fax me?
 

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Discussion Starter · #16 ·
Oh BTW, I noticed the "other" PS Board in the PS has a PJX-01 on it as well? Do both of them fry? Why not just take the 10 broken units and make 5 working units?


Or is my Power Supply a freakshow of components. (The other IC pack indeed has PJX-01 written on it as does the same looking pack on the Main PS Boad).
 

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Discussion Starter · #17 ·
Replaced ICP01 and ICP02.

Replaced another half dozen electrolytic capacitors.


The connection on C13 looked kind of bad and I wiggled it and the solder base ripped off (eeek) so I just soldered it back in line, used a continunity tester and got the beep so I guess it's okay.


However, the sound is still there.


Anyone have a dead power supply they want to sell me so I can try swapping in 'new' transformers?


Could one of those small capactiors (little honey-colored ones) actually make that sound?


What about the coils? (Blue capacitor looking things)


Any way to test a capactior without a capacitance meter? Or is an acutual capacitance meter a total waste of time? (looks like they just tell you what the value of it is, which I already know as it's written on the side).
 

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Hi ---


I have two working GP3000s of my own... and if someone solves this problem, I sure would like to know.


What does a used Power Supply sell for?
 

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Discussion Starter · #20 ·
The GP5000 supply is supposed to be the same as the GP3000. So I'd say, "Yes".


Used Supply? Dunno. Curt Palme has sold a couple I think. Could ask him.


I'd like to try a dead supply first since it's still working. Perhaps it is, as was suggested by someone, just the trasnformer coils getting loose.


This power supply has been worked on (prior to me). So I suppose it could be a number of non C13/IC01 things.
 
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