Sony CRT TV blue flashes - Page 1
Forum section: electronics / repair

author: belzrebuth
author_rank: Frequent Contributor
timestamp: March 23, 2023, 12:21:04 pm
content: Hi all,I've got a Sony KV-14LM1E without remote control which shows blue flashes while also displaying the signal applied.It's like part of the blue color comes and goes rapidly but the actual flashes are "bluer" than what they would normally be if the blue color would be missing and coming back.I hope this makes sense!I tried touching the joints on the heavier parts and replaced the color amplifier on the neck board just in case it was faulty but the problem persists.Hitting with a stick does not alter the problem but the flashing is quite rapid and eye catching so it's not easy to see if I can actually affect it by the hit test.I also tried flexing the board in various place but I didn't see any change; again the flashing is obscuring things a bit but I would probably know if it changes frequency; fixes itself etc.I would say it's consistent so I guess that this behavior rules out any connection problems.I don't yet have a sony remote control (plan to get one from a friend) so I can't access the diagnostic menu..Any ideas on what I could check next?ps: There's full schematics on the service manualhttps://elektrotanya.com/sony_kv-14lm1e_fe-2.pdf/download.html#dledit: I got the remote and the errors are as follows:OCP > 124IKR > 118V > 2Ι cleared those because I'm not sure if anyone else might had a go to repair it and maybe forgot a connector or so throwing an error.The one that went +1 again is the IKR (points to horizontal output circuitwhich seems fine since I do have horizontal deflection)

author: shakalnokturn
author_rank: Super Contributor
timestamp: March 23, 2023, 05:55:58 pm
content: I used to hate the Sony FE2 chassis, the most common fault was the flyback transformer failing (yours cold be on the way out going by the symptoms) when failing it would often arc and destroy a TQFP "jungle" IC that was well glued to the PCB and much fun to replace.One of Sony's worst designs ever, IMHO they're better off dead...

author: belzrebuth
author_rank: Frequent Contributor
timestamp: March 23, 2023, 08:56:50 pm
content: A little more info..The TV has a fair bit of noise on all channels except AV input channels.The green channel number segments are flickering and they are fuzzy/noisy.Upon start up the set works without the blue flashes; the standby LED blinks 5 times then goes off and blinks again until the blue flickering starts the standby LED stops blinking and stays off.I also tested most if not all caps out of circuit and I didn't find any faulty ones.The flickering problem occurs after a minute or so of normal operation.OSD and service menu are also fuzzy.The set cannot be turned on unless there's a remote command.I can't wake the TV from the front panel.IKR error persists so this could be something that I could start with.

author: shakalnokturn
author_rank: Super Contributor
timestamp: March 23, 2023, 11:24:04 pm
content: OK, so even if they're better off dead you really want to repair it...IKR could be internal to the CRT, red cathode shorting to filament or G1.In this situation I'd try crossing two outputs from the video amplifier, i.e. send Red video output to Blue cathode and Blue video output to Red cathode (of course the picture will be a little funky...) if flashing colour changes and still triggers an IKR fault you have a problem down stream, if it still flashes blue and this time triggers an IKB fault consider you have a defect on the red electron gun.Also check the CRT is correctly grounded, that noise in the video is another problem unless it all comes from the jungle IC that has already been whacked by a strike of EHT back through the ABL pin...Edit:Looking back at service manual, I assumed wrongly that IKR was red cathode current... I don't think crossing video outputs has much point. IKR fault code is vague in the service manual. Considering problems it would be worth checking supply voltages, particularly B+ and +8V. I still think considering the error codes it could still be the flyback transformer EHT starting to leak through the ABL pin, if it is you'll find out soon enough.

author: shakalnokturn
author_rank: Super Contributor
timestamp: March 23, 2023, 11:38:35 pm
content: I've just been trough my repair log...In 2010 I had a KV-14LT1B for repair, customer had dropped it, since it was triggering error 2 (OCP) only on bright images. For diagnostics I modified the current protection, it ran OK for about 2 hours then started triggering error 5 (IKR), I gave up concluding the CRT was dead.Take this with a pinch of salt, I could have overlooked something and if I had had more time available come to different conclusions.

author: belzrebuth
author_rank: Frequent Contributor
timestamp: March 24, 2023, 12:18:12 am
content: I found a video on YouTube of the exact same monitor and the noisy image on the RF channels is normal.Only the AV input channels are stable with no input.I think you're right about the CRT dying though, I looked the fault online and it's probably a bad tube.I already spent quite a bit of time on this so I might need to let it go but I'll check those voltages (B+ and +8) and report back!

author: shakalnokturn
author_rank: Super Contributor
timestamp: March 24, 2023, 12:32:04 am
content: Actually, looking back at it all I think it is still more likely to be the flyback than CRT, If you believe the electron gun is faulty you could still do the crossing video outputs previously described but if you look at the schematic around IC001, it's easy to see how surge of high voltage on the ABL line (and I insist this is their most common and most annoying fault) could trigger both 8V and OCP error codes, I can't speak for IKR, description is too vague...If you have a scope try looking at ABL for spurs / glitches, in normal conditions it should vary with overall picture brightness no spikes.

author: Runco990
author_rank: Frequent Contributor
timestamp: March 24, 2023, 04:09:42 am
content: A lot of trinitrons developed Heater to Cathode shorts. You can knock on the face of the tube and make it flicker, that's usually your problem. There is no cure. I used to repair Broadcast monitors for many years, most Sony. Sometimes superheating the cathode for a minute would help, as long as the monitor wasn't moved around, but that was on a "fatal" tube, so nothing to loose.Tap fairly hard with your knuckles on the front of the tube and see if it flickers. Or tap GENTLY on the neck with a screwdriver handle. I don't recommend that if you don't know how to handle CRT's. You could blow the tube if you don't have a feel for it.I always did that to see if I should even take the back cover off a monitor to service it or not.