tv philips 21PT3005 / 55 chassis L03.2L AA B + elevated in stamby 122v
What worries me is that the damage of the aforementioned components of insurance originated while in stamby, since the client told me that at the time of turning on the TV, it simply did not turn on. At no time did he tell me it was on and it went out. This is why I worry about delivering it that way. as I told you it has been running for hours without presenting any fault, but with this detail in Stamby.
What I deduced is that because the first electrolytic of + B was completely depleted: 2564 (47uF 160v), the horizontal output power transistor (TSH) was shortened, then due to excessive consumption it charred the coil or shock 5563 that carries the + ba leg 2 of the flyback and through the primary coil of this to the TSH collector. I also recommend controlling the 2nd. + B filter: 2305 (47uF 160v). The BUT11 or BUT12 of the market are very bad, I recommend a C6090 or BUL312 in = size or a TT2076 or BUV48C bending and fine-tuning the tips of the pins.
Good evening Jose Fernandez. Tomorrow I check the filters you indicate Thank you and I agree with your analysis. I had the TV on almost all afternoon and it hasn't failed, I just have the doubt about that voltage in stamby
Hi Jose, I do not think that being in std.by the TSH has been burned, since, until we give the order on, there is no oscillation and the horizontal output does not work. This must have been that Ms. gave the order on, the source started with excess tension (for an instant and then low) and said excess shorted the TSH. Therefore it is necessary to check well that source that at startup the voltage does not rise and then fall. This can be controlled by disconnecting the power to the flyback and charging between this point and ground with a focus of 60w or 75w and placing an analog tester on the + B.
and I say analog because it is better appreciated that the needle goes over the nominal voltage and then slowly decays. I'll send you later how that source works.
Source operation for L03 chassis: the tea1506t feeds its internal circuit by pin 14 with 1/2 wave through 3527 (2k) and coil 1-2 of the traffic (Safety restart mode). During this period the pin2 of the integrated will be below the vcc Start level (11v). The elect. 2521 (22uf 50v) is charged through the 2 R series 3506 (330k) and 3507 (33k) CHECK THESE. When its load reaches 11v, the excitation pulse will appear on pin 11 (driver) to the 7521 mosfet. When driving this, it circulates current through the primary of the 5520 (coil 1-3). When operating the integrated consumes
... consumes current and the voltage on its 2 VDC pin tends to go down more and more and the integrated stops being powered by the 2 R in series. When the voltage drops on pin 2 below 9v, the integrated stops producing excitation pulses to the mosfet and enters the Safety On mode. So that this does not happen and the source continues to operate, the relay winding pins 5 and 6 of the transformer act, which together with q7523 and d6520 charge the electrol. 2521 thus ensuring the supply to the integrated. The objective of the regulation circuit is to keep the + B constant. This tension is sampled through the ..
resistive divider r3543 (82k) and r3544 (6k8) in the secondary (REVIEW THE 2R) and taken to the base of q7540 (REVIEW). This has a constant voltage on its emitter for the zener 6540 (6v8) (REVIEW) so any variation in its B causes variation in its C and since this is a current sink of the opto 7515, its effect is reflected in pin 6 ( control) of the IC. If the load increases, the voltage drops by + B, less C current flows through q7540 and the voltage at the E of the opto (pin3) will be lower, which will cause the integrated to increase the excitation pulses to the mosfet. If the load decreases, the tension in
in + B increases, the current in C of q7540 drops, there will be greater voltage in E (pin 3 of the opto) and this will cause the integrated to decrease the mosfet pulses. Normally operating the voltage on pin 6 (control) of tea1506t will be within its normal range (1v) for high consumption and low switching frequency and 1.42v for low consumption and high frec. switching
Joselopez61, I'm glad you solved it, but pin 1 of the UOC (std.by cont.) That you said you canceled is not a protection, but the one that gives the source on and off order from the emitter of transistor 7541 So for me it is a miracle that being that pin1 of the disconnected uoc can turn on and off ....
Dear nicomena, thank you for your input. I agree with you that the voltage should be maintained, normally there is a difference of 3 volts between stamby and on I have already repaired several philips TVs with this chassis and it has always measured me 94 or 95 vdc in stamby and 97 vdc in on. Tomorrow I change the filter that you indicate and perform the tests.
good afternoon companions and I made the changes of c2528, c2521 and c2561, 2564 and 2405 of + b had already changed.
but it is still the same. Now I could observe something else. When it is on and I give the order to turn it off, the voltage goes up to 102vdc then goes down to 95 vdc and from there it starts to go up and now it is reaching 125 oscillatingly between 121 and 125 vdc
Therefore, he says that the fault has been solved ... it is only carried on stand-by ... look for an R of 22kohm x 2w and connect it between + by mass ... and see if in stand-by it goes down a bit the voltage .... if you see that, lower the voltage and reheat the R of 22kohm see how we solve it .... you changed the C2561 of 2200mfx25v ... ok ... comment results ...
Nicomena friend if I changed the c 2561 2200mfx25v but it stayed the same. However. I was reviewing the diagram and I took the voltage measurements again in tr 7541. which according to the diagram must have in its base 3v3, in transmitter 3v3 and in collector 8v1, those voltages have them present with the tv on. but in stamby I have 3v3 in base, 1v7 in transmitter and 4v in collector. and there comes the result of the test I did. I disconnected pin # 1 from the uoc 7200 (pin # 1 = stamby) and the stamby voltage normalized at 95 vdc. and the tv turns on and off normal
well buddy ... from me (congratulations) x the achievement ... no longer has a prob, with the stand-by voltage ... it only remains to verify temperatures in the TSH and regualcion of the + b .... good luck ....Cheers!!!
Thanks nicomena. I really believe that what I did was to cancel a protection (std_con) I'm going to test it for a few more hours to see how it goes.
Leave a comment in case I'm doing well I give you the solution. because you took valuable time and accompanied me to the end.
Well, colleague: ... I just have to congratulate you for the solution given to a philips tv ... at the same time I will share it with colleagues since, these TVs are not easy to repair ... if you want to value my contributions you can do it under my first comment ... this way it can remain in the archive of solutions for other colleagues .... until another opportunity .... luck .... greetings !!!