Thank you Gents.
Before I got a chance to read your last responses I went ahead and put a 1Ω (1.2 to be precise) 1/2 watt resistor on there to test it out.
The meter came on just as it did with the E and B of Q657 shorted.
It had lights on everything but there was no illumination on the CRT.
Funny thing happened when I cut the unit off though.
I saw a FLASH of the signal trace on the screen.
I repeated this again and saw the same thing.
This indicated to me that the CRT was actually on.
I read that a common problem with these units...
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Thank you for this explanation [USER="29541"]redwire[/USER]
Didnt see it yesterday.
Firstly, I already tested C689 (along with all the other major caps) and it is surprisingly okay (cap=113µF; ESR=0.28Ω)
Taking [USER="137730"]petehall347[/USER]'s cue I went and checked out these brown things and 2 of them read 1.2Ω.
The other one (R651 on the bottom left of the board) is dead (reading -4.3 MΩ and fluctuating).
Cosmetically it looks in better shape than the other 2.
Thank you Pete for dropping me that bread crumb....
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Also the line in the center is a filament/wire. It wraps around one leg several times crosses over the brown body wrapping it once then terminates by wrapping around the other leg. It feels like a rudimentary fuse of some sort but its likely resistor of some sort. I'll take its measurement tomorrow to see if I can identify it via the schematic....
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It has physical cracks/chips/defects on it yes but it reads continuous when I checked it with a meter. Im not exactly sure what the name of this component is TBH but there are 3 or 4 of them around the perimeter of the PCB.
The one by the serial power connector is in worse shape than this one......
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Thank you for the reply [USER="29541"]redwire[/USER]
My apologies and you are right about that being a transistor and not a cutout.
Not sure what I was thinking there.
Its labelled Q657 and its has to do with the display's lights.
Specific to the AC supply is [URL]https://w140.com/tekwiki/wiki/File:Tek_422_acps.png[/URL]
The schematics for this unit can be found on its tekwiki page:
[URL]https://w140.com/tekwiki/wiki/422[/URL]
You are definitely right that the caps (and even diodes) need to be checked and i hope to...Last edited by KYBOSH; 02-04-2024, 12:15 PM.
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Okay I went ahead and bypassed the thermal cutoff/fuse and the unit powered on.
I figured with the power supply out of the case the temperature of the unit couldnt rise fast enough for me not to notice it.
The cutoff likely failed due to age and stress.
So the scope powers on but nothing is on the screen.
One battle won and another one begins.
I'll keep this thread posted of what I discover.
I'll try to replace parts with OEM if they are available and reasonable in cost.
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Tektronix 422 with No Power
Picked up a Tektronix type 422 oscilloscope locally for a few bucks last year.
It wouldnt power on at all so I stowed it away under my bench for later testing.
Today I remembered it was down there and pulled it out to see what was what.
I checked for continuity and everything checked out.
There was a burned smell and a resistor was replaced with a temporary replacement (see yellow box in picture).
The burned smell is very pungent/acidic and I am not familiar with these vintage electronics to know whether I am smelling the remains of the replaced resistor or...1 PhotoLast edited by KYBOSH; 02-03-2024, 08:32 PM.
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Re: Service manuals available free
OMG... why is this thread not a Sticky?
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Re: Sony KD-55XE8505 black screen with sound
Your issue is likely with the panel or the circuit boards connected to it. You'll have to use a multimeter to find the bad component if the problem is on the panel boards. If its within the panel itself you will need to cut certain traces to eliminate the short.
These things are not for the inexperienced.
You are dealing with VERY small components and very thin/small traces.
One slip or false move and your panel will be inoperable.
Most times when you have panel issues the TV is not worth dealing...
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Re: Onn 100012586 vertical lines
This is very interesting...
One side causing distortion on the other side.
Dont think ive seen that before.
They should be independent unless its an issue with the T-con board itself right?
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Re: Samsung UN55HU8550F - No picture, No sound
Just to tidy this up... I was not able to find another working board for this TV. I came across several from TVPartstoday but they all had one unacceptable fault or another. Like not responding to IR commands and things like that. Pretty rare TV to find in the wild and even rarer to find a good mainboard. I eventually gave it to someone to give it a try as it was sitting on my to-do list for about a year.
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Re: Philips Hue Go Light Repair Attempt
So i spent the late evening going thru and replacing any and all caps they looked funny to me. In all i replaced 4 of them but no joy. After replacing C2 it read as shorted. I removed it and tested the pads and they both read shorted as well. I probed all around and couldnt find anything else that could be causing this. All the resistors were good and within specifcations. The transistors nearby were okay too. I am leaning towards the theory that the short/fault is within that big Hue Engine chip. The flashing purple light is most likely an...Last edited by KYBOSH; 10-23-2023, 12:53 AM.
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Re: High-ambient-temp smoke sensor recommendation
Without a picture or make/model to reference its hard to fully appreciate or help with this issue. Sounds like the major issue is the heat source. Either its not rated for the task or its not being properly maintained. Perhaps it can be upgraded to something safer or with a higher rating?
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Re: Samsung Q6F edge LED section not working
+1
You 'MAY' be able to rotate the diffuser 180° degrees so the cracks are at the top and a fresh clean surface is mated against the LEDs but many of the diffusers I have see wont allow this. Either there are tabs on the diffuser to ensure it cant be install backwards/upside down or the etching stops 0.5" from the end instead of going all the way to the end. The lack of etching (not the right word but you get the idea) will prevent proper diffusion and distrubution of the light emitted by the LEDs....
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Re: Samsung UN65KS8000 wont boot, restarts, display damage 💔 Worth a shot?
Thanks for the insight. This is caused by trauma at that spot correct? Too much pressure/weight at the corner like some when moving the TV and leaning the it on that corner? Or maybe from inserting a tool (thin screwdriver) to remove the back cover?
Trying to understand what 'may' have happened so I dont make a mistake like that. When I first turned on the TV to inspect it I dont recall seeing that spot but the backlight never stayed on for more than a second and it was...Last edited by KYBOSH; 10-22-2023, 11:56 AM.
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