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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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REQ: Emerson 19" tv TC1993 no power
Need info on low voltage regulator str 30130.
Any advice appreciated. TIA Jan |
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Emerson 19" tv TC1993 no power
Here...
http://www.nteinc.com/specs/1700to1799/NTE1776.html kip -- "Watch the return E-Mail addy its false" "Jan" wrote in message ... Need info on low voltage regulator str 30130. Any advice appreciated. TIA Jan |
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Emerson 19" tv TC1993 no power
Jan:
If it is not putting out regulated B+ @ 130 V DC it is most likely faulty..... obviously the other supporting circuitry can cause a B+ faults like shorted loads (always look for a bad HOT), bad pre-regulator diodes and filter, faulty base drive/reference, open resistors, etc. The STR 30130 is usually a fairly reliable unit as long as it is heat sinked well and the solder connections aren't cracked or dry.... or there isn't a fault before or after the chip. Pin 1 Common Pin 2 Base Pin 3 Input Pin 4 Output Pin 5 n/c Best Regards, Daniel Sofie Electronics Supply & Repair - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - "Jan" wrote in message ... Need info on low voltage regulator str 30130. Any advice appreciated. TIA Jan |
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Emerson 19" tv TC1993 no power
On Thu, 19 Feb 2004 10:26:01 -0800, "Sofie" wrote:
Jan: If it is not putting out regulated B+ @ 130 V DC it is most likely faulty..... obviously the other supporting circuitry can cause a B+ faults like shorted loads (always look for a bad HOT), bad pre-regulator diodes and filter, faulty base drive/reference, open resistors, etc. The STR 30130 is usually a fairly reliable unit as long as it is heat sinked well and the solder connections aren't cracked or dry.... or there isn't a fault before or after the chip. Pin 1 Common Pin 2 Base Pin 3 Input Pin 4 Output Pin 5 n/c Best Regards, Daniel Sofie Electronics Supply & Repair - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Thank you for your input. I am first year EE student and appreciate your efforts. I have no voltage out of the regulator. There is a relay that is not energizing and I assume that;s because there is no high voltage. A viscious circle. How to continue? No schematic . Thanks again Jan |
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Emerson 19" tv TC1993 no power
Jan:
Slow down a little.... there is a lot of successful troubleshooting and repairing that can be done without a schematic. Take some time and trace the circuitry with your eyes..... checking different components with your DMM. There is no high voltage because there is no regulated 130 v B+ coming out of the chip and there are a lot of reasons that there is no voltage coming out of the chip....... is there "raw" B+ at pin 3 ? (~ 150 V) of the regulator chip as referenced to pin 1? Did you check for shorted parts and components in the circuitry after the chip? (see my previous reply post with suggestions) Do you have a replacement chip that you can install? -- Best Regards, Daniel Sofie Electronics Supply & Repair ----------------------------------- "Jan" wrote in message ... On Thu, 19 Feb 2004 10:26:01 -0800, "Sofie" wrote: Jan: If it is not putting out regulated B+ @ 130 V DC it is most likely faulty..... obviously the other supporting circuitry can cause a B+ faults like shorted loads (always look for a bad HOT), bad pre-regulator diodes and filter, faulty base drive/reference, open resistors, etc. The STR 30130 is usually a fairly reliable unit as long as it is heat sinked well and the solder connections aren't cracked or dry.... or there isn't a fault before or after the chip. Pin 1 Common Pin 2 Base Pin 3 Input Pin 4 Output Pin 5 n/c Best Regards, Daniel Sofie Electronics Supply & Repair - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Thank you for your input. I am first year EE student and appreciate your efforts. I have no voltage out of the regulator. There is a relay that is not energizing and I assume that;s because there is no high voltage. A viscious circle. How to continue? No schematic . Thanks again Jan |
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Emerson 19" tv TC1993 no power
On Sat, 21 Feb 2004 07:30:47 -0800, "Sofie" wrote:
Jan: Slow down a little.... there is a lot of successful troubleshooting and repairing that can be done without a schematic. Take some time and trace the circuitry with your eyes..... checking different components with your DMM. There is no high voltage because there is no regulated 130 v B+ coming out of the chip and there are a lot of reasons that there is no voltage coming out of the chip....... is there "raw" B+ at pin 3 ? (~ 150 V) of the regulator chip as referenced to pin 1? Did you check for shorted parts and components in the circuitry after the chip? (see my previous reply post with suggestions) Do you have a replacement chip that you can install? Thanks for the advice . I have been doing some eyeballing with mag glass also and cannot see any open traces etc. Volt reg chip has 0 volts on pin 3. Volt reg chip pin 3 goes to the relay contact through a resistor that is not open. I also have obtained a capacitor esr tester and I am in the process of testing some caps in the power areas. Hot appears to test ok out of circuit using meter diode testing bce; but I have no reference to compare. base collector 520 ohms and base emitter 49 ohms; I believe this is because of diode internal. I will be obtaining an HOT and volt reg chip on Monday and will keep you informed of my progress. Thanks Jan. |
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Emerson 19" tv TC1993 no power
Jan:
You might check for a 3 terminal regulator chip.... maybe a 7805 or 7806.... on the board that supplies standby voltage to the syscom chip.... sometimes near and around the VCR circuitry.... if there is no standby B+ going to the syscom chip then it won't energize the relay when the power button is pressed. -- Best Regards, Daniel Sofie Electronics Supply & Repair -------------------------- "Jan" wrote in message ... On Sat, 21 Feb 2004 07:30:47 -0800, "Sofie" wrote: Jan: Slow down a little.... there is a lot of successful troubleshooting and repairing that can be done without a schematic. Take some time and trace the circuitry with your eyes..... checking different components with your DMM. There is no high voltage because there is no regulated 130 v B+ coming out of the chip and there are a lot of reasons that there is no voltage coming out of the chip....... is there "raw" B+ at pin 3 ? (~ 150 V) of the regulator chip as referenced to pin 1? Did you check for shorted parts and components in the circuitry after the chip? (see my previous reply post with suggestions) Do you have a replacement chip that you can install? Thanks for the advice . I have been doing some eyeballing with mag glass also and cannot see any open traces etc. Volt reg chip has 0 volts on pin 3. Volt reg chip pin 3 goes to the relay contact through a resistor that is not open. I also have obtained a capacitor esr tester and I am in the process of testing some caps in the power areas. Hot appears to test ok out of circuit using meter diode testing bce; but I have no reference to compare. base collector 520 ohms and base emitter 49 ohms; I believe this is because of diode internal. I will be obtaining an HOT and volt reg chip on Monday and will keep you informed of my progress. Thanks Jan. |
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Emerson 19" tv TC1993 no power
Jan,
One end of the relay coil connects to the standby power supply, the other end to the relay switching transistor. The standby supply powers the microprocessor, relay switching transistor and relay coil. When the power button is pressed the microprocessor turns on the relay switching transistor supplying 5 volts through a resistor to the base. The relay closes and provides input to the STR30130. Look to see is the base of the relay switching transistor getting its forward bias when the power button is pressed. Gordon Gaskell AAS Home Electronics of Havre de Grace, Maryland |
#9
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Emerson 19" tv TC1993 no power
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