REPAIRING AND NOT THROWING AWAY

REPAIRING AND NOT THROWING AWAY

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and technical information about Service Modes, Circuit Diagrams, Firmware Update procedure, Disassemble procedure, Universal remote control set-up codes, Troubleshooting and more....

If you go into the profession, you will obtain or have access to a variety of tech tips databases HERE IT IS Master Electronics Repair !.

These are an excellent investment where the saying: 'time-is-money' rules. However, to learn, you need to develop a general troubleshooting approach - a logical, methodical, method of narrowing down the problem. A tech tip database might suggest: 'Replace C536' for a particular symptom. This is good advice for a specific problem on one model. However, what you really want to understand is why C536 was the cause and how to pinpoint the culprit in general even if you don't have a service manual or schematic and your tech tip database doesn't have an entry for your sick TV or VCR.

While schematics are nice, you won't always have them or be able to justify the purchase for a one-of repair. Therefore, in many cases, some reverse engineering will be necessary. The time will be well spent since even if you don't see another instance of the same model in your entire lifetime, you will have learned something in the process that can be applied to other equipment problems.
As always, when you get stuck, checking out a tech-tips database may quickly identify your problem and solution.In that case, you can greatly simplify your troubleshooting or at least confirm a diagnosis before ordering parts.

Happy repairing!
Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

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..............The bitterness of poor quality is remembered long after the sweetness of todays funny gadgets low price has faded from memory........ . . . . . .....
Don't forget the past, the end of the world is upon us! Pretty soon it will all turn to dust!

©2010, 2011, 2012, 2013, 2014 Frank Sharp - You do not have permission to copy photos and words from this blog, and any content may be never used it for auctions or commercial purposes, however feel free to post anything you see here with a courtesy link back, btw a link to the original post here , is mandatory.
All posts are presented here for informative, historical and educative purposes as applicable within fair use. NOTHING HERE IS FOR SALE !

Saturday, 16 February 2019

JVC TV POWER SUPPLY SRP- 9022 A-M2 AND SSR-9011A-M2 PWBS FUNCTION CHECK

JVC TV POWER SUPPLY SRP- 9022 A-M2 and SSR-9011A-M2 PWBs FUNCTION CHECK

                                        SRP-9022A-M2 PWB [JVC POWER SUPPLIES]
     This PWB utilizes power supplies whose standby Vcc is created by a circuit that is separate from the Switching Circuits.
     When the AC cord is plugged in, Standby circuit should function.  This circuit will supply the Vcc to system control IC.  Check this voltage first and continue:
  • Check for Standby Vcc at the specified location.
  • If standby Vcc is not functional, begin at the oncoming AC Line Voltages and check all voltages supplying the Standby Vcc circuit. 
                                                        SRP-9022A-M2 PWB
Check these parts for any damage if standby voltage is not developed at power ON.
  1. F905 > Surge protection.
  2. D901 & C907 > Main rectifier.
  3. IC 911 > Switching regulator.
  4. D911, R911 & C914 > Startup.
  5. T921 > Switching transformer [Failure to this part is very rare]
  6. R923, C903 & R920 > Current feed back.
  7. FR915 & D912 > Run DC.
  8. PC 921 > Opto Coupler [Photo-coupler]
To check whether Standby voltage is there, Short [CN90SE], plug in AC, and measure the Vcc at IC9141.
     This PSU PWB does not unitize a Switching Circuit during Standby mode.  Therefore these circuits cannot be tested in this PWB, other than the stand by voltage.
     Check point [Standby voltage] Check Pin-1 of CN90G.  5V should be there.  If not check for the reason.  Check the 5V regulator.  Check all the solder terminals for any loose or dry solder.  If suspected, re-solder all of them by applying a little more fresh solder, without making any solder bridge short in between adjacent solder terminals.  Make sure to unplug the AC power cord before  attempting to solder.  All points here will be HOT while plugged in.
B1 Voltage High | Low secondary voltages.
  1. Leaky error amps may cause high B1 voltages. Check voltage at error amplifier.  If it is excessive or abnormal change the Zener Diode on between Photo-coupler and error Amp may cause similar low power issues.
  2. No Standby Vcc.  In many models, the transformer, regulator or rectifier circuit fails.  Check the input to the Bridge Rectifier then measure the DC output voltage at all points up to the regulator to locate the faulty component/s.  In models with Standby supplied by switching circuits, measure the supply voltage to this circuit.  Many times, other PWBs have failed in the TV shorting the supply line for standby voltages. Special care should be given in checking the ceramic disc capacitors if used in circuit. Ensure the Circuit Protectors have not blown on this supply line.  
  3. Power On | OFF rapidly:  This can result from many things.  But the likely culprit is the supply to the switching IC.  This is similar to what causes lamp flicker, the power supply is oscillating due to insufficient supply voltage.  Check the circuit that supply the Run DC and Start up DC.  Measure the Ramping Voltage at the Feed back.  If it is less than [0.8V], meant the IC is not stable.  
  4. Lamp Flicker in HDILA:  Run DC is important to maintaining a stable supply.  If this is low the supply may oscillate.  It will be best to replace the main rectifier [Stalk or individual 4 diodes used].  In most cases, ow Run voltage can be due to defective main rectifier diodes.  Check the main Filter Capacitor too. Replace is also with a new one is adviced.  If Run voltage is low, or it oscillates, these pulse will appear in the voltage and HDILAs, as this might result the lamp to flicker.  Check the circuit that supply the Run DC and Startup DC.  Measure the Ramping Voltage at the feedback.  It it is less than 0.7V, means the IC is not stable.  Replace the Photo coupler too. This component also can make unpredictable symptoms of faults.  Give attention to Zener diodes too.  Desolder out one end of them, and check it out from the circuit.  
Posted By: FRANK at 07:39
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