Re: Tecnoware FAL501FS12 does not turn on
can you tell me if this transistor can be problematic?
can you tell me if this transistor can be problematic?
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Re: Tecnoware FAL501FS12 does not turn on
I do not know if there is a problem with the transistors, If they were shorted they usually burn the 10Ω (next to the driver transformer) or the 1.5K (next to the small diode near the white plug and fuse)
The KA7500 has vcc but also needs to be turned on, If it is turned on and working, it will output drive waveforms to the two small transistors connected to the T2, these small transistors drive T2 which drives the two primary transistors.Last edited by R_J; 04-15-2020, 03:23 PM.Comment
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Re: Tecnoware FAL501FS12 does not turn on
so what do I do? of course I try to change them, if that is not the problem how do I proceed?Comment
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Re: Tecnoware FAL501FS12 does not turn on
Change what? the transistors? the ic? Have you tried reinstalling ALL the parts and see if the power supply works? The power supply might not try to turn on because it does not see any voltage on the +12v or +5v supplies.
While you have the main primary transistors removed I would change those 2 small electrolytic caps near Q7 and Q8 They are the same ones listed on the schematic as C7 and C6or8? (10µf/50v)Last edited by R_J; 04-15-2020, 03:51 PM.Comment
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Re: Tecnoware FAL501FS12 does not turn on
of course I tried, every time I change some component I put everything back and try again, I am making attempts, otherwise I was not here to ask you for help, my knowledge stops at bad capacitors and burnt schotty mosfets and diodes, at the bridge rectifier, in short those common things, since I can't go further I'm asking for help, maybe my culture on switching power supplies will be widerComment
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Re: Tecnoware FAL501FS12 does not turn on
already done, the capacitors have all been changed, they are all new, later I try to change the npn transistors, if it doesn't work it could be one of the ics?Comment
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Re: Tecnoware FAL501FS12 does not turn on
Do you get any voltage on the +5 or +12 (even 1or2v) when you turn on the power supply?
There is 16 volts on the KA7500 pin 12 which is good. There should also be part of that voltage (10~12v) going to the drive transformer, I traced the path so can you check the small diode next to the 1.5k and the 1.5k and the 100Ω (in green square) I also marked the schematicAttached FilesLast edited by R_J; 04-15-2020, 05:54 PM.Comment
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Re: Tecnoware FAL501FS12 does not turn on
no, I don't have a minimum voltage in the outputs even on the 3.3v ... then summing up, I have to check the goodness of those components that you reported to me and see if I have 12v on that yellow track? sorry if I ask you but I'm using the translator and it's not always clearComment
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Re: Tecnoware FAL501FS12 does not turn on
Is there any other voltage on the KA7500? I know pin 12 has 16 volts but what about the other pins?Comment
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Re: Tecnoware FAL501FS12 does not turn on
I only checked pin 12 as it was recommended to me, what other pins should I check?Comment
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Re: Tecnoware FAL501FS12 does not turn on
about post # 68 you didn't reply to me if I understood what to do or notComment
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Re: Tecnoware FAL501FS12 does not turn on
I only asked if there was a small amount of voltage on the 12 volt line to see if the power supply tried to start and maybe shut down. It is not that important now.
It is important to have voltage on the drive transformer. That voltage supplies the collectors of the two 2sc945.
On the KA7500, check pins 16 and 15Comment
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Re: Tecnoware FAL501FS12 does not turn on
ok in a while I reassemble everything and check, I want to change the two transistors now that I have disassembled them and there is one that does not convince meComment
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Re: Tecnoware FAL501FS12 does not turn on
I reassembled everything, I replaced the transistors but did not want to know how to turn on, on pin 15 we have 4.99 volts on pin 16 2.80 voltsComment
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Re: Tecnoware FAL501FS12 does not turn on
I have practically changed all the components, it is driving me crazyComment
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Re: Tecnoware FAL501FS12 does not turn on
but now on the transformer I have 6.50 volts when it is on, 1.50 volts in standbyLast edited by falcontech; 04-16-2020, 08:25 AM.Comment
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Re: Tecnoware FAL501FS12 does not turn on
no, I don't see anything but nothing, there is no shadow of tension, I tried to replace the ka7500 with a tl494 taken from a working power supply but nothing does not start, could it be lm339?Comment
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Re: Tecnoware FAL501FS12 does not turn on
i tried to change also lm339 nothing moves, tell me what i can try now it has truly become a mysteryComment
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Hi guys, I’m back here my friend give me her tv, that doesn’t turn on and no standby red led. When u plug in the cord the red led of one two second is on, then turn off. If you push the power button or the remote the red led blinks but nothing happen. I give u some photo with voltage, don’t look the fuse….because I blow it for mistake nd I dint have the right replace so I just put it for test the tv. The standby voltage should be 11,88 volt on the diode, but I have 13 volts. I put in the photo the different volts I test and there are someone negative…I don’t know if it s normal. On... -
Greetings!
Thank you in advance for your understanding, I am writing to you through a translator.
A Harman Kardon AVR171S amplifier was given.
The history of the machine is as follows:
It was faulty when I bought it, I want to fix it.
I replaced the HDMI switch and one of the DAC ICs in it.
After that it worked without a problem.
I watched a movie using the amplifier, and at the end the amplifier got really hot.
The cooling was faulty, I will fix this later.
I switched it to standby mode, waited for... -
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Hello,
I need advice in troubleshooting Telefunken TV (it is actually Vestel). There is red Standby light but TV cannot be turned on either by remote control (which is good and tested on another TV) or by actual on/off switch at the back of the TV.
Power board is Vestel 17IPS71 and I'm not sure about the mainboard, it seems like 17MB82S
Both boards are shown in the attached photos.
What is normally first that is checked in this case. I have removed power board, make sure it has no dangerous voltage on the big caps and check many components (transistors and diodes)...
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