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#1
12-19-2008, 01:20 PM
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Prima TV Model Q2016 Comes on when Plugged In
I have a Prima CRT television model Q2016. It powers up immediately when it's plugged in. There is no picture or sound. You can't even bring up the menu. If You push channel, volume, or TV/Video on the front panel, the set will shut off. All power supply voltages seem to be present. I checked the clock, and data lines at the eeprom with a logic probe. The pulse signals seemed to be messy in my opinion. Not sure if I should chamge the micro IC, or the eeprom, or both. Any help would be appreciated.
Thanks... 
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#2
12-20-2008, 09:50 PM
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I've never worked on a "Prima", but your problem is definitely micro-related. It seems to be performing the POR (power-on-reset) and nothing more. Have you checked the crystal (or resonator) that feeds the clock signal to the micro? I've seen a few Sanyo and Sharp sets that had bad/dead micro clock crystals. Then again, it could be a stuck data line from the EEPROM to the micro - scope those out to see.
Cheers,
__________________
Brian USN RET 22YRS (Avionics/Cal) CET-Consumer Repair and Avionics ('88) "Capacitor Cosmetologist since '79" When fuses go to work, they quit! Last edited by Findm-Keepm; 12-20-2008 at 09:50 PM. Reason: spelling...
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#3
12-20-2008, 11:37 PM
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I checked the crystal, and it seems to be working. There's a nice sine wave signal at the test point for the clock input to the micro. What would cause a stuck data line, a bad micro?? I checked the clock and data lines with a logic probe. The pulses didn't seem clean. Seemed to be garbled and messy. I tried the scope, and I didn't seem to get a clean signal of pulses either..
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#4
12-21-2008, 12:59 AM
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Guess it is possible that an overvoltage fault at the micro's power input could cause it to be permanently altered or damaged in this way. Surges can do that.
 Hopefully the fault was on the AC line and not due to a failure in the set's PSU section.As I'm understanding it, if you test the clock lines with a scope, you'll need one with a sufficient high-frequency testing capability to test the actual operations of the system. A simple ohmmeter or test signal can assure the physical connection...
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#5
12-21-2008, 01:13 AM
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Most of the failed microprocessors that I've run into were due to lightning damage. Some would cause weird symptoms just like you describe; but, most would short and load the B+ to the chip down. Just today, I was working on some POS Philco mid '90's color set made by some unknown company. The 5V to the micro was very low. I unsoldered the B+ input to the micro and the 5 volts came back up. I yanked the chassis for spare parts and pitched the rest.
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#6
12-21-2008, 02:10 PM
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My voltages to the micro and eeprom are all good. The set came to me in this condition. The owner of the said said that his 3 yr old daughter decided to keep pushing the power button on the front causing it to be in this state. I did change the micro but, just after I did I slipped with my meter leads and unfortunaletly caused a problem with the power switching regulator that caused the set to turn of and on by itself constantly until unplugged. I then made another error slipping with the meter leads blowing up the switching regulator. I replaced the regulator, and an open 1 ohm resistor in the secondary power section. After that it was back to square 1. So I'm thinking, I could have repaired it, but because of my slippery leads killed the new micro..?? I'm gonna try another one. Wish me luck....
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#7
01-16-2009, 06:02 PM
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Well, I changed the micro IC, and the set still has the same problem. I'm convinced that the fine folks at Prima have sold me blank eeprom's and not ones programmed with revision E438 as I ordered. ARRRRGGHHH!! Help!!!
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#8
01-16-2009, 10:33 PM
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What are the chances that the power switch is damaged? RCA sets had bad push buttons for awhile.
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#9
01-18-2009, 04:35 PM
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The power push button is OK. If I plug the set in and get the power up with no video, or sound scenario, then I pull the eeprom from the socket, then I push either TV\Video, Channel up\Dn, or Vol up\dn I get a blue screen with not quite full deflection. i think the eeproms that prima sold me were blank. I want to take action. Anyone have bad experiences dealing with prima???????? I want to build a simple eeprom reader to confirm that the eeproms are blank. Anyone know of a simple schematic, and good free software to just read an I2C eeprom M24C08???????????????????????????????????????????? ????????????????
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#12
01-26-2009, 09:20 PM
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Check eserviceinfo, they seem to have many dumped eeproms from various TV manufacturers.
http://www.eserviceinfo.com/index.php?what=search2 Here are some russian TV repair sites with dumped EEPROMS: http://www.sper.hr/eng/master_tv.htm http://www.sper.hr/eng/radiofan.htm http://www.sper.hr/eng/rc5.htm http://www.sper.hr/eng/radiomaster.htm
__________________
This device isn't a spaceship, it's a time machine. It goes backwards, and forwards... it takes us to a place where we ache to go again.
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