sir, when power on the monitor screen show blue with retrace line but next time power on the display is white with retrace line (this is IBM CRT 14”monitor model no – 6540 – 02e) and horizontal out put transistor(C5802) is very hot. how i solve this out put hot problem and retrace line ?
retrace line are due to excessive g2 voltage or G1 voltage is too low. Sometimes a weak screen also can produce retrace lines. Before that you must check why the HOT is so hot. Could it be the B+ voltage is too high or the signal pulse to base of HOT is abnormal or if the flyback itself have problem?
Thanks for your last mail. I always read your blogs & articles. From your articles I have got so many important things which is now helpful for my repairing sites specially crt, lcd monitor repair & smps troubleshooting.
I hope your success in life.
All the best.
Yes Jestine, I didn’t expect that C990 have high ESR value, also I replaced some high ESR value el-caps in that area and the monitor is so far so good.
By the way, the CRT picture tube is still valuable here, because a company here will make it as a second hand CRT TV. Does it need some modification on the monitor picture tube before making it adaptable to China TV mainboard?
Have a pleasant fishing trip,
Congratulation! As for the CRT, the most important to check on the crt monitor before fitted with the crt tv board is the spec of the yoke coils. A wrong spec could cause the TV HOT to burn.
Hello Sir Justine,
Thank you for the article that you have share, and thank you for the information too. I have read your interview to Mr. Don, and Mr. Steve. I also thanking you for forwarding this to me, it makes me to have more interest to learn further about the system, and how does components work. May God Bless you always.
With full respect,
Thank you so much I had download the e books . these are the
best books and practical point to repairing switch mode power supply.
I early begin to learn about electronic as hobby because it’s very interesting
My name is Rukan i have problem with my China TV. which have LA76810A, LC863532C and HT24LC08 ICs. after 5 or 10 minutes the tv lose the channel. i thing that slowly slowly change the channel.how i fix this problem. Please, give me solution for this problem.thanks
This could be the problem of a bad supply voltage to eeprom IC or the eeprom IC data have corrupted.
Hi Jestine. I have a Lazer Disc Player that has currently quit playing and I was wondering if you could help me fix it. I am good at electronics to a certain point, but I need your help. The motor has stopped spinning the table and I don’t know why. If you have some info on this (a DVD player, VHS, etc) that would help me ALOT! Thank-you for your info on ALL the things you have published to this point. I have used your info in different things I have fixed. You have saved me alot of money, and I aprriciate that, especially in todays times.
This is the nearest i can find:
In your case, you need to make sure the output voltages from the power supply are good. check backward from the motor since the motor is not getting the supply voltage.
Mr jesine I just want you to helpme how to remove those those Reddish colours on the screen or redish picture or screen!
Compare the red and blue/green transistor voltage and signal. If the voltage/signal is good then probably the tube have problem. Sometimes it can be the setting problem in the eeprom have corrupted and you need to enter the service mode to adjust it. Usually only the authorized service center knows the code of the service mode.
hello sir, how was day i hope everythink is ok.
Sir i have problem with the above tv at the secondry power supply output i cheak all the secondry output diode and i come across b+ diode and i get two reading i remove it from the board and i get one reading, then i follow that line by cheaking the component on that line up to the b+ pin of the playback transformer when i cut it then i get one reading. so sir is this means the playback transformer have the problem? or their is another component to be cheak againt?.Thanks
It can be the flyback have shorted or the horizontal output transistor (HOT) shorted.
Hi jestine, Really quick question im repairing a motherboard and found 3 bad caps near the cpu, these are 3300uf 6.5v ,I dont have any of these lying around so can i replace them with 4600uf 6.5v ?
I think i can but just checking first.
Yes you can.
I have a 29″ samsung crt tv with a blinking standby LED and when I load a bulb at the B+ line and the light blinks? Any ide what is the problems?
After loading the light still blinks then this suggest either the power supply can’t deliver the power (power supply problem) or one of the output lines have problem. Try use the resistance to check on each line (except the B+ voltage line) to see if there is any shorted component.
Hello again Jestine,
I have attached some pics of the issue with the TV I was telling you about. Sorry my camera couldn’t take a better picture.
It seems to be the green color section have problem. Since the red and blue color circuit are working fine thus I suggest that you compare the signal/voltage with between the green and red/blue circuit. Any differences in the result will lead you to where you should troubleshooting the point for bad component/s.
Hi Mr Young i have this panasonic national tv when switched on it
shows red led light and makes a rattling sound somewhere around the
transformer for about 5 seconds then stops. But the screen does not
show only the red led light. If you switch off the sound does the same
again. What might be the problem .
It could be the problem of bad flyback. before that make sure the output voltages from the power supply are good. Make sure the CPU is getting 5 volt. Red LED could means the CPU or EEPROM is not working or the “On” signal is not reaching to optoisolator ic (if this tv have one).
I test the yoke for continuity with a multimeter and also examined it for burnt or corroded areas. The B+ supply voltage without the yoke is 128.2 volts.
You need to test the yoke with blue ring tester as checking the yoke with multimeter is not accurate. The B + seems to be good.
now i repair a crt monitor. its problem is no display but power led glow green. first time i disconnect the cpu then measer voltage in crt base bord G1 voltage is -19v , the screen is white (plain raster). i connect the cpu now G1 voltage is – 78v , when the cpo ON the G1 voltage is – 120v , G2 voltage 250v , RGB voltage 102v . this condition no display on screen how i solve the problem? base bord ic MM1203S .
I Suggest that you trace from the G1 pin because if it is more than -100 volt there will be no display. It can be an open resistor or a leaky transistor. Sometimes a bad eeprom data also could cause such problem.
Hi sir i need your help i have an stereo amplifier pioneer model SA-570 it come for repair complain with no sound with power on in testing all the components in pws and audio section all find good except the reley type DH2su 24v is not work so i test it with ohm meter read 1k ohm so i dont know if its good or not please help thank
Testing relay you need to remove it out and power up the coil winding with the respective voltage. if the volt is 24 then you need to connect to 24 volt. You should hear a click sound. If it is an electronics relay you will not hear the sound. If you place your ohmmeter probes across the other two pins, you should get a reading once the relay is clicked.
I’ve got a problem of a printer power supply that blows off the main filter capacitors ( 2x 1800uF 200V ).I have replaced the first set and it has now blown a new set. What could be the cause of this.
The voltage across the cap could be too high or the cap is of a low quality. Check the ac supply and make sure the dc voltage at the bridge is within the value.
before we repair any electronic equipment we need to do a shot circuit and continue test so we could find out where the shot is or if a part is defective so we could find out in which area. do you know about how to do this test with a multimeter please i need to know asap
If you purposely short the circuit you actually create more works. There is no end in creating a short circuit. You should remove the components of a working equipment and see the result. For example you can remove the supply pin of the vertical IC in a crt monitor or crt tv. It should have one horizontal line. In the future if you come across any one horizontal line problem you will know which section you need to check ie: the vertical section, supply voltage and surrounding components.
By the way i will be on holiday tomorrow morning and will only check email once I’m back on Saturday night.
i have a question about a DVD player JWIN. In the power supply the tea1522p shorted and can’t find a replacement but i have in stock tea1523p. Do you think the TEA1523P COULD BE A LIKELY replacement? Thanks
There are different in the internal ohms reading. You can try that but I can’t guarantee 100% it will work.
pls help me out, i am working on a sharp tv, 21inch, model 21S-FX10F,the problem is power LED BLINKING(going dim and then brighten up, go dim again and so on) the screen remain dead no HV, i open the cover and saw one burnt resistor in position R844 i replaced with 100ohm, did some voltage testing on some points, the result is,
1. main cap.=270V dc.
2. HOT—collector=125.5V, base=0.
3. horizontal drive transistor—collector=12.05V, base=0.45V.
4. horizontal yolk terminal—125.5V each with socket on.removing socket 1 pin= 125.5V,the other=0V. i also tested HOT in cct using analog mm black probe on collector and red probe on both emitter and base each and get no reading, i do not have scope to test HOT base, This set uses TDA12156H1/N2/3/AB9 as main ic(smd) and there is a mosfet K2161 at horizontal cct, also there is this regulator with 4pins (050RDA1), at switch on the voltage on i/p pin is around 9V, o/p 5V but within some seconds just about time for the screen to glow the voltages will change to i/p 12V, o/p 1.5V, the 4th pin goes to the main ic and reads 1.45V, the o/p feeds mainly the tuner, and branches to the same main ic and audio ic(la42102) i have disconnected the tuner pin but no success, pls assist me. also how can i test this 4pin regulator?, can i carry out voltage testing on FET pins? if yes how. thanks, your books are great asset to hold on to, and i will soon order for your burnt resistors value e-book also. thanks
The first section to check is
1) is all the output voltages from the power supply good and stable?
2) If it is good then did the eeprom and the CPU getting 5 volt?
3) If yes, then is the B+ voltage to the flyback normal?
4) If yes then is there a pulse to the base of the HOT?
A TV or monitor should have a good B+ voltage and pulse to the base of HOT in order to produce the high voltage. missing either one will cause no high voltage symptom. In this case of repair scope is most useful. Pin 4 of 050RDA1ic signal sould be come from the CPU. If the signal is not correct then the input/output voltage could be affected You also need to make sure the cpu crystal have sinewave.
i have pcb in that pcb vcc and gnd are shorted,how we can rectify problem.
It depends on what type of broad. If the board is too complex then you need a short locator.
Sir, the problem of the above tv is that when you turn it on in a few second it show FACTORY on then right angle of the screen and at the botom of the screen it show a paclock, the remote control can not make any function expect power position. Sir i want know what shall i do to solve this problem, thanks.
You need to find the service manual to enter the service mode. Before that make sure all the voltages to the eeprom and cpu ic have 5 volt and the front control button is not stuck.
Hi mr Yong. Its Lwazi here in South Africa. My problem is as follows : im repairing an LG rear projection tv, i have fixed the power supply but now im stuck with this I.c. The number is STK 396-130. I think its for switching on the lcd. I have looked arround but i cant find it, what comparison can i use in the place of this IC? I will appreciate yo help. Regards Lwazi Malisa.