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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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 Link Posted: Mon Jun 15, 2009 9:00 pm Post subject: Latest Score....... |
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Not really my own personal score but I'm directly involved.
So we're up here in Pa. for the last few weeks and the motorhome is parked in a friends driveway and hooked to his power and water (good friend). So a week and a half ago were talking about tv's and stuff and I'm telling him about my flat panel deals. Last Sunday he's out doing yard sales and there is a sign on a table...free tv. So he asks the lady and she takes him into the house (expensive house area) and there's a 65 inch Sharpvision RPTV. She says it wont turn on so they just want it gone. So he loads it on his trailer and home it comes. Still looks like new on the outside.
So I look up the specs and its a CRT based unit...  About 8 years old and cost 7300.00 new and 1080i.
We plug it in and hit the button, hear the click then chirp, chirp. Curt knows what that means... 
I open it up and see Hitachi tubes, colored C elements, almost no wear, first surface mirror......
About 20 minutes of testing and 10 minutes online and the part is on order. 2 days and $5.69 later and she's running like a charm. Last night cleaned all the optics and touched up the alignment and she's screaming a beautiful picture.
Guess I can stay parked here for a few more weeks as I earned my keep........ 
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AnalogRocks
Forum Moderator
Joined: 08 Mar 2006
Posts: 26690
Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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| Link Posted: Mon Jun 15, 2009 9:02 pm Post subject: |
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What'dya doin' here? Get back to work!
Nice score!
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Tech support for nothing
CRT.
HD done right!
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Link Posted: Mon Jun 15, 2009 9:14 pm Post subject: |
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| AnalogRocks wrote: | What'dya doin' here? Get back to work!
Nice score! |
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ecrabb
Forum Moderator
Joined: 13 Mar 2006
Posts: 15909
Location: Utah
TV/Projector: JVC RS40, Epson 5010
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| Link Posted: Mon Jun 15, 2009 9:17 pm Post subject: Re: Latest Score....... |
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| macgyver655 wrote: | We plug it in and hit the button, hear the click then chirp, chirp. Curt knows what that means...
I open it up and see Hitachi tubes, colored C elements, almost no wear, first surface mirror...... |
What does that mean? I've had several high-quality SMPS's (usually in computers) die over the years, and that's the typical failure mode... the "chirpy" sound... What the hell is that, anyway?
We always replaced the module and shelved the bad one because I don't know component troubleshooting. I'd love to learn more advanced troubleshooting and component-level stuff, but there's only so many years in a lifetime. If only there were an "Electronics Troubleshooting and Repairs for Dummies" guide. 
Nice score!!!
SC
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Link Posted: Mon Jun 15, 2009 9:28 pm Post subject: Re: Latest Score....... |
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| ecrabb wrote: | | macgyver655 wrote: | We plug it in and hit the button, hear the click then chirp, chirp. Curt knows what that means...
I open it up and see Hitachi tubes, colored C elements, almost no wear, first surface mirror...... |
What does that mean? I've had several high-quality SMPS's (usually in computers) die over the years, and that's the typical failure mode... the "chirpy" sound... What the hell is that, anyway?
We always replaced the module and shelved the bad one because I don't know component troubleshooting. I'd love to learn more advanced troubleshooting and component-level stuff, but there's only so many years in a lifetime. If only there were an "Electronics Troubleshooting and Repairs for Dummies" guide.
Nice score!!!
SC |
The chirping sound is the power supply being overloaded, usually from something shorted out. This also applies to the high voltage and/or deflection section as was the case on this one. Then you begin your testing on high temp devices which are usually on heat sinks. I actually found the shorted diode in about 5 minutes but spent another 15 minutes testing along the path of the shorted component to make sure nothing else was damaged or that something else didn't cause the damage. Everything else tested good so it just needed the 1 part which is common.
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ecrabb
Forum Moderator
Joined: 13 Mar 2006
Posts: 15909
Location: Utah
TV/Projector: JVC RS40, Epson 5010
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| Link Posted: Mon Jun 15, 2009 10:17 pm Post subject: |
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OK, that all makes sense... But, what if there was nothing wrong with the device itself... It was the PSU that actually failed. Turn it on, the computer won't power up, but something in the PSU keeps chirping. Replace the PSU and everything is good to go. I realize it's probably not the actual failed component, but what component is it specifically that makes the chirping sound? I've always wondered.
SC
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MikeEby
Joined: 24 Jun 2007
Posts: 5238
Location: Osceola, Indiana
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| Link Posted: Tue Jun 16, 2009 12:59 am Post subject: Re: Latest Score....... |
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| macgyver655 wrote: | Last night cleaned all the optics and touched up the alignment and she's screaming a beautiful picture.
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Your post inspired me to clean the optics and tweak the focus pot on my 9 year old 55" Mits HD-RPTV....WOW what a difference for about an hour of work, I was considering replacing the old girl...Not anymore, Thanks Mac!
Mike
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24305
Location: Langley, BC
TV/Projector: All of them!
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| Link Posted: Tue Jun 16, 2009 1:06 am Post subject: |
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| ecrabb wrote: | OK, that all makes sense... But, what if there was nothing wrong with the device itself... It was the PSU that actually failed. Turn it on, the computer won't power up, but something in the PSU keeps chirping. Replace the PSU and everything is good to go. I realize it's probably not the actual failed component, but what component is it specifically that makes the chirping sound? I've always wondered.
SC |
THese are switching supplies, like in most CRT projectors. A failure within the power supply or an external short will all result in chirping, which is the SMPS running at a way lower frequency than normal (100-200Khz), which you can't hear. The SMPS are designed to turn power way down when an overload or short condition is encountered, thus not blowing the supply up, as a plain old bridge rectifier 'brute force' supply would.
Faults in any SMPS can be almost any part. IN no particular order I've had:
- bad capacitors
-bad chips
-bad transistors
-open resistors
-open PC board traces
- short internal to the switching transformer. (don't even ask HOW LONG the first one took to find when I first had this)
(OK, it was about 2 years! I'd hung onto about 6 supplies that chirped that I couldn't figure out, and one day I finally realized that the only part I hadn't changed was the transformer itself. Swapped it in one supply and sure enough, it fired right up. Pulled out the other 5 supplies in my junk box, and got all 5 of those working within an hour. Measured the transformer on my inductor tester, and each had shorted windings internal to the transformer. Go figure.)
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Link Posted: Tue Jun 16, 2009 2:27 am Post subject: Re: Latest Score....... |
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| MikeEby wrote: | | macgyver655 wrote: | Last night cleaned all the optics and touched up the alignment and she's screaming a beautiful picture.
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Your post inspired me to clean the optics and tweak the focus pot on my 9 year old 55" Mits HD-RPTV....WOW what a difference for about an hour of work, I was considering replacing the old girl...Not anymore, Thanks Mac!
Mike |
Sure thing. I still love the picture these old beasts produce when they are clean and aligned. Just wish the off axis was better.
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ecrabb
Forum Moderator
Joined: 13 Mar 2006
Posts: 15909
Location: Utah
TV/Projector: JVC RS40, Epson 5010
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| Link Posted: Tue Jun 16, 2009 5:34 am Post subject: |
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| Curt Palme wrote: | | THese are switching supplies, like in most CRT projectors. A failure within the power supply or an external short will all result in chirping, which is the SMPS running at a way lower frequency than normal (100-200Khz), which you can't hear. The SMPS are designed to turn power way down when an overload or short condition is encountered, thus not blowing the supply up, as a plain old bridge rectifier 'brute force' supply would. |
Wow, thanks for the awesome post, Curt! I knew I had a good reason for not even trying to diagnose and fix one of those PSU's before. Too damn many things that can be wrong with it and WAY beyond my skill or interest level...
Not to be ungrateful, but you guys STILL haven't answered my real question!!! What is the actual component that MAKES the chirp sound? Is it the transformer oscillating like the flyback in a TV? What actually MAKES the sound?
Sorry to be so demanding! 
SC
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Link Posted: Tue Jun 16, 2009 2:05 pm Post subject: |
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The chirping sound is actually a normal sound in the transformer as the magnetic field collapses from the voltage dropping out. In a normally functioning power supply you can sometimes hear 1 chirp when you turn it off. The continued chirping in a non functioning P/S is the voltage coming up and going back down in a consistant fashion. It wants to come on but as it comes up the short loads it down. Then it tries to come up again and so on......
Let me also add that the actual noise is the change of the oscillating frequency.
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betel
Joined: 20 Apr 2006
Posts: 448
Location: Maryville, Tennessee (Just South of Knoxville)
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| Link Posted: Tue Jun 16, 2009 3:00 pm Post subject: |
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To elaborate:
During the initial electro-magnetic field build up, huge currents flow through the coils due to at t=+0, z=Rcoil. These huge currents result in high forces acting on the coils. These forces cause the whole transformer to vibrate. In large transformers say that feed a building, it is more of a loud thump than a chirp. After steady state is reached, you only hear a hum because the currents are much lower.
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