Plug set in stand by is there,set turns on b+ regulates at 130v.hv measures 20 kv then shuts down. never see filaments lite. don't have a manual. am thinking ihvt is bad? any help would be apprecieated thanks jim
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Re: popwers on /off shutdown
I just checked with my distributor for the flyback for this model, and it comes up as an inactive part with the notice that Sanyo states they can no longer sell parts for this model, and that you must call sanyo direct at 800-877-5032 for information. They must have serious issues with this set. Sanyo used to put out a good product some 30 years ago, as I recall.
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Two basic ways--most shops use a ringer---with flyback out they connect across the primary (where sweep transistor collector goes to where that lead on the transformer exits--a good bad indication is seen.
Second way is voltage into the transformer is tested and High Voltage is measured at the CRT---usually if transformer bad you will have 4kv or so (4,000 volts) and the suspect is clear.
If HV just comes up full (over 20 Kv) and drops to zero it is not the problem and something is shutting the set down.
If model number listed here (kv-27fs120) is correct the set if not coming on is in shutdown because either a problem in its power supply or something elsewhere pulling the supply voltages down and triggering shut down.
Someone would have to open and first check for voltages and or shorts--no real other easy way to troubleshoot this.
Hello, The power light may be flashing or if you are runing with a series light bulb it may be cycling on and off continuously. There may be a chirping or clicking sound from inside the set. (Note: using too small a series light bulb load during testing for the size of the TV may also result in this condition.)
If there is a low voltage regulator or separate switching supply, it could be cycling on and off if the horizontal output, flyback, or one of its secondary loads were defective.
Does this TV have a separate low voltage regulator and/or switching power supply or is it all part of the flyback circuit? For the following, I assume it is all in one (most common).
Some simple things to try first:
Verify that the main filter capacitor is doing its job. Excessive ripple on the rectified line voltage bus can cause various forms of shutdown behavior. An easy test is to jumper across the capacitor with one of at least equal voltage rating and similar capacitance (make connections with power off!).
Use a Variac, if possible, to bring up the input voltage slowly and see if the TV works at any point without shutting down. If it does, this could be an indication of X-ray protection circuit kicking in, though this will usually latch and keep the set shut off if excessive HV were detected. Good luck...
Although the other response is in much better technical lingo, it sounds to me like the television had a high voltage arc which I have seen on quite a few of the sony big screens lately. Usually, it causes a part on the circuit board, (one of many that were listed on prev. solver's list) to fail. This causes a delimma for the repairman, because when they find the bad part and replace it, sometimes it will pop again causing repeat failure of boards and/or parts on the board. Sony is known for having bad tubes on their projection sets, and it can be a difficult repair even for a trained tech. I suggest calling a sony service center in your area, and get an accurate estimate before deciding if replacing the set is the best idea. Hope this is helpful input, Russmann.
you will need the flyback as thats way to low. The HV splitter will only direct the HV to each of the CRTs it doesnt change or regulate the HV in any way just directs (splits) it. Let me know if you need any more assistance.
This sounds like the shutdown circuit is shutting down the TV due to an over current condition. This overcurrent condition is caused by a component in the HV section drawing excessive current.
the 5 blinks is a visual indication of the problem.
If the set runs at all, your flyback and output transistor are good. If the set shuts down after a few seconds and the sides are wavy, it usually means that the main B+ in your power supply is too high and not regulating properly. I do not know what kind of power supply that model uses, but if has an old-style STR regulator (like the STR30130) then it is probably shorted, and if the set uses a switching power supply then look for an open or leaky electrolytic cap on the primary side. If the power supply is working correctly and the set shuts down, check for an open safety cap (the large 1.6 - 2Kv cap connected to the collector of the horizontal output transistor).
The high voltage should be around 29.5 KV and not fuctuate between 20-30 KV that would indicate a high voltage regulation issue then. Are the filaments lighted up in the neck of the CRT? If so then yes you are probably looking at a low voltage issue such as a 12 volt source or a a/v switching IC issue.
if the screen gets really bright then shuts off its going into protection shutdown. Could be a bad or shorted green tube. Or your missing the drive voltage from the sweep supply that suppys b+ to the screen transistors or the High voltage block. This is a hard thing to track down without monitoring points in the curcuit. If you troubleshot electronics i would start with measureing the screen voltage first. If thats ok then i would then monitor the HV shutdown triger point to see if the problem lies from the HV going to high and if its shutting down from an overload then test the green crt. if thats good disconnect the green 2nd anode lead from the HV distribution block to see if its in the green tube or from the High voltage. Any way your gonna need a service manual and a schematic and you can order that from sams photo fact.com ood Luck