F70 Tell us on what to look for board resistor R1702 and transistor Q1702? And what foot solder a resistor to the transistor (collector)?

Check the video output circuits on the base card of the TV. Check for any loose soldering on that board. Resolder all the suspected solder terminals by applying a little more soder. Check the video output transistor for [Red]. If it is found faulty, replace it. check the resistor connected to the collector terminal of this transistor for open circuit.

Tell us on what to look for board resistor R1702 and transistor Q1702? And what foot solder a resistor to the transistor (collector)?

solution about f70 on my amplifier to remove

You mean the collector voltage on the Horz output transistor is 200 volts?

I would check this by removing the transistor and then measuring the voltage on the board (where the collector or center leg of the transistor is soldered to).

I don't know what kind of tv this is but you should see 130v or 135 volts.
RCA sets you should see 140v. If the voltage is too high replace the voltage regulator.

I have just repaired one with similar problem.
Check solder joints at transistor reg Q1701, Q1702 and resistors R1701, R1702 on
digital PCB .

SA-DX750 (sister Model to SA-DX850). Showing error code F70, after a few minutes running. Checking the power rails revealed +5VA and +5VD, on the Digital Circuit Board 'A', dropping to about 2V, when fault occured. F5, T1A, on the Sub-Transformer Circuit 'M', was subject to occasional blowing. The problem was traced to an intermittent break, in the printed circuit board conductor, in the vicinity of Q1702 (+5VD regulator) collector, on the Digital Circuit Board 'A'.. Repairing this cured the problem. Note that removing F5 (above), or disconnecting CN702, CN1000A or CN904B, on the Digital Circuit board 'A', also causes this error code to be displayed. Failure of the audio output ICs, IC651 & IC801, is apparently the usual reason for this error code being dsiplayed, but it is worth checking the power rails viz. +/- 25V (Fuses F3 & F4, T6.3A, on Sub-Transformer Circuit 'M') +/- 55V, +/- 14V etc.

Are you talking about the LV power supply or the HV power supply? The terminology your using is related to the horiz drive circuit. Have you checked the B+ off the regulator which should be about 120v or, it will on the pc bd for the correct voltage. Do you have sound? If you do then you will have to use use your scope to see if you have proper drive at the base of the Horizontal Output Transistor. Then we can go from there. Oh, by the way I can tell by the voltage readings you stated both of those transistors of turned off.

Hello sedekim,

First check you connections to the circuit board some times the connections go bad from the deflection board to the signal board, if this is not the case the bottom advice may be of help.

That problem indicates that the Horizontal Output Transistor (HOT)is beginning to malfunction. I would suggest that if you have a background in electronics that you do the following:

1) unplug and open the back of the set

2) look for the HOT and locate the Collector, Base and Emitter of the transistor and using your multimeter set to read resistance measure from the collector to the ground, it should read high almost infinite, red from base to ground it should read low and from emitter to ground it should read low.

3) if the HOT when read from the collector to ground reads low then you can bet that the HOT has a short circuit from collector to ground, and will have to be replaced.

4) In addition I would also perform a ring test on the Integrated High Voltage Transformer (IHVT).

This will tell you if the IHVT has suffered any damage from the HOT malfunctioning. You may end up having to replace both of the components.

If you do not have a background in electronics I would suggest that you take the TV to your local TV repair facility.

Thank you,

Shuttle83

http://www.electron-age-technologies-llc.com

If you can still see the video and some fine white lines running diagnally across the screen, it is very likely the picture tube itself which would likely be covered under warranty. If it is a solid green screen with no video, it could be a defective driver transistor or IC going to the picture tube.

F70 interrmintent problem caused by (Ic-current) interupted, supply for cpu, Q1702 (emitter point) high resistant to IC1701, suggestion- connect a wire between these component due to pcb track poor contact.