REPAIRING AND NOT THROWING AWAY

REPAIRING AND NOT THROWING AWAY

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and technical information about Service Modes, Circuit Diagrams, Firmware Update procedure, Disassemble procedure, Universal remote control set-up codes, Troubleshooting and more....

If you go into the profession, you will obtain or have access to a variety of tech tips databases HERE IT IS Master Electronics Repair !.

These are an excellent investment where the saying: 'time-is-money' rules. However, to learn, you need to develop a general troubleshooting approach - a logical, methodical, method of narrowing down the problem. A tech tip database might suggest: 'Replace C536' for a particular symptom. This is good advice for a specific problem on one model. However, what you really want to understand is why C536 was the cause and how to pinpoint the culprit in general even if you don't have a service manual or schematic and your tech tip database doesn't have an entry for your sick TV or VCR.

While schematics are nice, you won't always have them or be able to justify the purchase for a one-of repair. Therefore, in many cases, some reverse engineering will be necessary. The time will be well spent since even if you don't see another instance of the same model in your entire lifetime, you will have learned something in the process that can be applied to other equipment problems.
As always, when you get stuck, checking out a tech-tips database may quickly identify your problem and solution.In that case, you can greatly simplify your troubleshooting or at least confirm a diagnosis before ordering parts.

Happy repairing!
Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

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..............The bitterness of poor quality is remembered long after the sweetness of todays funny gadgets low price has faded from memory........ . . . . . .....
Don't forget the past, the end of the world is upon us! Pretty soon it will all turn to dust!

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Tuesday 26 February 2019

BPL GBR 9308 _ GBR-II 9308 [SET DO NOT START. POWER SUPPLY OK]

BPL GBR 9308 _ GBR-II 9308 [SET DO NOT START. POWER SUPPLY OK]

 Make sure that all the voltages at the secondary of the converter transformer are OK.  If not, check SMPS section as described in previous post.

To check the secondary DC voltages, connect a 100W filament type blub acorss the cathode of [D361 - EU2A], and Ground. Disconnect the coil [L 361], by desoldering it out from circuit.  Measure all the voltages comes from the secondary of the inverter transformer. The voltage between the cathode and Groundof of  (D361) or  (voltage acrosss (C 363 - 220Mfd 160V).  Make sure that the voltage meausred is 115VDC.  A slight variation about +2V or _ve2V can be tolerated.

After making this voltage to OK, reconnect L361 in place, switch ON the set.  Measure the voltage acorss C365.  Must show around 180VDC.  It will be there, if above stated amin voltage 115V is OK. 
Locate [R432 - 330 Ohms 1W] resistor on main board, which supplies voltage to horizontal driver transistor.  This voltage is taken from [27VDC] from SMPS power supply.  If there is no voltage at the collector point of the driver transistor [Q421 - 2SC2383]., chak the continuity of primary winding of line driver transformer [T431], and resistance value of R [R432]  there must be a slight voltage difference between two end of the primary winding of [T431], if line drive frequency from [TDA8305] is OK.

If you have a digital multimeter which can count frequenct, the service work will be very easy here.
Check the frequency of the base of Horizontal Output Transistor [Q432 - BU508DF].  It should be around 15625Hz.  If not, suspect the horizontal oscillator section.  Check the frequency and the base of line drivere transistor. Here also, the frequency must be almost same as stated above.

Desolder out the horizontal output transistor [Q432 BU508DF], and switch ON the set.  If frequency measured at the points stated above is OK, make sure that BU 508D is defective.  Still there is no oscillation can be measured, suspect [IC 101- TDA 8305A].

But, before replace it, you have to make sure that the line output transofrmer [LOT] is right.  There is no way to check the secondary higgh voltage winding to this transofrmer.  The only way is to check the heat of the horizontal output transistor [BU508DF].  Just replace the transistor, and switch on the set for a short period of time, say 5 seconds or so.  Switch it OFF, unplug it from AC mains wall socket, and feel the heat of the horizontal output tranistor by touch.  It can be slight warm.  If it overheats, make sure that the LOT is defective, and that was the sets' fault.
Posted By: FRANK at 05:58
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