Thursday, January 16, 2014

Email support between me and a customer from Barbados

This is Winston from Barbados, haven't spoken since March last year. Since then I have acquired an analogue ESR meter, very easy to use, and it immediately showed up faulty capacitors that I would not have found before.

 I am still focusing on CRT TV's though quite a few people are coming to me requesting flat-screen TV repairs. I still have a very large CRT market available here, and I want to repair ALL, except those where Tube is at fault.

I need to access your "blog" where I can type in a word or fault and get the relevant information, I did it a while back to get an understanding of how the degaussing circuit relay worked, but I can't remember how to access that information now. The webpage used to have a green background... 

Thanks for your email and glad to hear from Barbados...Sure it quite long since I heard from you but I am happy you are doing well.

 With regard to the question of searching my blog, it is true the “search this blog” gadget was not working for some times but the problem has now been restored and you can continue searching.

 Maybe I should simply ask you what it is I really want to know; Is there a way to confirm that the pulse is getting into the horizontal drive transistor base, other than using an oscilloscope? I do not have one yet, and I have backlog of CRT TV's with no light on screen, no high voltage, even though B+ is OK at collector of HOT, lamp burns steady at input break to FBT. This is very common fault I am seeing here.

Yes, if you get the voltage at the base of the drive transistor is around 0.6Vdc, this means the transistor is ON, if it is zero volts see if there is any voltage on the collector leg of the same transistor, if no voltage on the collector leg check backward what is blocking this voltage, maybe an open resistor (usually big) or dry joints.

Usually when you repair  TV sometimes it get okay but goes into sleep mode, when this happen use the TV remote control to fire up the TV…maybe the one you are talking about are just asleep waiting for you to wake them up using remote control POWER ON BUTTON. If no remote control press the menu /Channel change button on the TV itself

Also, numerous cases with TV shutting off as soon as you power it on. I want to know how to test FBT.

If a TV goes into shut down immediately after power ON, this usually point to some kind of over load, in most cases can be even a simple problem like dry joints, so whenever you get this symptoms start with re-soldering all areas where you see poor soldering especially the areas around the fly back transformer, both the primary and secondary side of the power supply.

The best tester for FBT is the flybak tester, if you don’t have one you can easily make one yourself using the information on this link.

Make one with confidence, I did mine using the same information and I have been using it for last 5 years without any problem.

 It seems normal for some F.B.T. pins to appear shorted to ground, but without schematic or markings on the circuit board, how do I know which ones should be and which ones shouldn't?  

The rule of thumb is that you should never get a beep when testing between the live (like B+) and the ground. Also you should not get any beep between the primary and the secondary pins of the transformer…FBT being one.

The primary pin is just the input pin(B+)...

Please note that this B+ pin get into the FBT and out again to the collector of the H.O.T transistor and therefore expect a beep between the B+ pin and the middle pin of the horizontal output transistor(H.O.T)

Regards Humphrey Kimathi


  1. Congrats brother, customer support is mandatory. I can see you really know how to do it, cheers keep it up.

    1. Thanks for your feedback and passing by Judy...

      Regards Humphrey