View Full Version : uratech 5inch b&w transistor tv


timmy
09-19-2012, 12:14 PM
does anyone know about these cheapo solid state bw tvs. this one i have when you push power the hv squeaks for a second and thats it no hv almost like there may be a timing cap in the circuit that may be bad. this set is from april 1986 so im sure most of these sets from that vintage may have had the same problem so if anyone can steer me in the direction of this possible cap or reason why the pulse is not running i would be greatful for the info.:sigh:

AiboPet
09-19-2012, 03:49 PM
I don't REALLY have much to add to this....but I did Google "uratech TV" and got this ebay link so that maybe I could figure out just what one of these was.

http://www.ebay.com/itm/URATECH-DELUXE-5-PORTABLE-B-W-TV-W-AM-FM-RADIO-BATTERY-AC-POWERED-/260974380713

I actually happen to NOT have one of these or any of it's "sisters". This TV appears to be a rebranded reference design made by someone else. I recognize it as one I see called "Bentley" quite often. It might help you track down a schematic if nothing else.

My "general" tech bench experience with all the little chinese b/w sets I do have.....usually end up in finding cracks in the board (look for them around the area where the "round" flyback footprint is). If you suspect something looks like a crack in the trace....a simple "beep" check or however you like to check continuity with your meter on a point either side of the crack. Look for real suspicious electrolytic capacitors that are swelled on top....or sitting weird on the board like they may be swelled on bottom. Obviously look to see the back of the CRT and it's socket look okay. Usually if one of these is dropped, it won't usually break the cabinet except in extreme cases....but will usually break the PC board along an edge.....or right around the flyback (because it is relatively heavy during a fall and will stress the board as soon as the set hits the ground).

Otherwise....I'd really only look for cold solder joints, touch up ANYTHING that looks suspect. Touch up pretty much every "wire" soldered to the board like the yoke and CRT wires. I've seen ALOT of cases where the vertical will go away....and the yoke wires were cold solder points, etc.

As far as any real measuring.....I'd really only go as far as to trace 12V (likely) around from the power plug to the power supply regulator (usually a transistor looking item with a heat sink VERY close to the power plug). I'd check to see if anything at all was getting to the Horizontal Output Transistor (usually close to the flyback).

I HAVE gotten much deeper into these before just because I was bored....or STUBBORN, but usually I just don't get that far into these unless I can find schematics (REAL hard to find for these)

My money is on "it's broken and you WILL see it" if you are careful looking at the PC board. These just don't have bad parts like the "big boys" do...because they just aren't old enough to "wear out" until they are from the 70's or earlier. That being said though.....I HAVE been stumped by a few of these "simple" sets, and I usually then just write 'em off and KEEP the parts to fix others. This of course only really works if you are collecting ALOT of the "same set" (as I do with the little "Coby" sets).

Sorry for the long post.....but this generally describes what I see in like 90% of these SMALL sets.

Playing with these really little sets differ from the big roundies and consoles...BECAUSE they are portable, get dropped, see weather, a CAT can knock one off a table....and these also tend to be used in REALLY crappy situations like sitting in PILLOWS on a bed or whatever, get thrown in closets and stuff. They almost ALWAYS suffer more "physical" trouble than anything else.

timmy
09-19-2012, 04:29 PM
well ok great info besides who knows what this thing has been through over the years so ill look into possible trace issues. maybe it was dropped at one time. this set uses 8d batterys or the dc adapter so i dont know if it has a regulator yet but ill find out. thanks for the info ill post what happens.

AiboPet
09-19-2012, 07:34 PM
It'll have a big 'ol regulator for sure. If there wasn't one, the picture would jump allover the place at the slightest voltage variation. You would usually see this if you turned up the volume. Same thing happens if you use a wall wart of too little amperage (usually these like to at LEAST see 750mA or so....more typically 1A).

Since you ARE getting "somethng"...such as it is, I would suspect you DO have power beyond the regulators and switches. Look closely at the flyback area....because you described a small "horizontal squeel" that then stops. Sounds ALOT like the horizontal oscillator starts, and then is shut down by a horizontal output or HV problem. Try looking at the set running in a dark room and see if the filaments are coming on behind the CRT. You should quite easily see the orange glow. Do you get ANY audio at all?

timmy
09-19-2012, 08:01 PM
yes the crt lights up and if i switch the set on and off this is when ill get some lines on the screen and only when turning it on i get a split second squeak from around the fly. it has a am fm radio built in and works as well as audio from the tv.

AiboPet
09-19-2012, 09:36 PM
Of COURSE you did diddle with the brightness/contrast just to make sure they aren't both all the way down. The "lines on the screen" seems to indicate you DO have HV...even if just for a second. You obviously DO have power as well. If you have full radio and can tune in a TV station even with only sound, you seem to have all the tuning. If you had SOMETHING and then suddenly NOTHING on the screen, this is "probably" not in the sweep circuits. A "vertical" problem would be a bright white HORIZONTAL line. A horizontal problem would be either a bright VERTICAL line or nothing at all (still possible). I would check the "pots" (variable resistors) for your brightness/contrast. Make sure those have not been loosened from the traces of the PC board by someone pushing on them real hard, etc. I suspect the "squeel" you hear for a fraction of a second is likely just the horizontal "coming up".....unless it sounds extremely odd and irritating. If you are still young (or haven't destroyed your hearing yet)....you may be like me and still can HEAR most analog TV sets running. If you don't hear this when watching an NTSC set...then you may just be hearing THAT circuit "ramping up" to it's normal frequencies.

Of course without a schematic.....you sorta hafta KNOW what sort of "landmarks" to look for that indicate what section of the set you are looking at.

I still suspect a physical break somewhere. Check those pots, check the traces all around those. You may wanna just touch up all the (usually three) solder points under each one. A b/w set usually has like four of them all in a row if you don't count all the little trimmers for height, linearity, course horizontal, offset, voltage regulation, etc that are ON the board. Also....I wouldn't "play" with any of the tiny pots until you actually have a picture to work with. Just the regular "outside" ones like contrast, brightness, horiz and vertical. Tweaking any that have to do with horizontal that are not the regular outside one...can take the horizontal WAY out of range and can shut down the set if you aren't careful.

timmy
09-23-2012, 06:45 PM
well i have no hv yet on this set but im going to try a long shot and go ahead and change the horiz&verticle processor IC and see where it goes. the hot is good and there is another transistor on the board that gets tied into the flyback and thats good as well. i think if the fly was shorted then the transistor would have been shorted as well but its not. so if this IC dont work then maybe a timing capacitor is bad but to find which one without a schematic will be hard.

Sandy G
09-23-2012, 07:32 PM
The more I read/see/hear about these El Cheapo last-gasp Chinese Junque TVs, prolly the most amazing thing was that ANY of 'em actually worked...Down here, they could be had all day long for $20 each...And as little as $9.95 if you did some looking...They cost the jobber/wholesaler what, $5-6 apiece, then ? I don't see how they were a viable commercial product at all...

timmy
09-23-2012, 07:36 PM
The more I read/see/hear about these El Cheapo last-gasp Chinese Junque TVs, prolly the most amazing thing was that ANY of 'em actually worked...Down here, they could be had all day long for $20 each...And as little as $9.95 if you did some looking...They cost the jobber/wholesaler what, $5-6 apiece, then ? I don't see how they were a viable commercial product at all...

lol,lol yes they are junk but what the heck it keeps me busy, and besides it only cost me 5.00,lol......

AiboPet
09-23-2012, 08:28 PM
And to me.....it seems once YOU end up with the set, and correct whatever ABUSE or carelessness the thing has gone through, they do pretty much STAY working when you give it a GOOD home. I've fixed up some pretty hairy pc board, flyback and "case all busted to hell" problems in the last few years.

Sometimes I just like to remember the STORY behind finding and fixing the set. More than a few times I have spent WAY too much time, energy and even MONEY fixing something I just wouldn't give up on. I've done this for as silly a reason as "COOL!..I never saw a green one before!".

It's a SILLY hobby sometimes.....but if you are fixing them up for anything like making a dollar, it would be a pretty LOUSY paycheck. You hafta WANT to have all the little sets around, for whatever funny reason. I'm gonna hafta slow down picking these little sets up allover the place. My flat is starting to look like I'm the CAT LADY of micro TV sets!

timmy
10-04-2012, 05:17 PM
well this little chinese set looks like it needs a flyback which i am sure ill never find one but it does have a number, KFS-20851 maybe someone knows where to find one.

timmy
10-07-2012, 07:25 AM
well i got another set the same as above now this one the crt heater voltage is to low.the heater dont glow and cant figure where that supply comes from. this one has hv.

timmy
10-08-2012, 07:29 AM
well i am still at it and i find that for some reson the boost votage is not there and the hv is at 2500kv not enough but also found that alot of 16v caps have no voltage then put a jumper from 12v to one of those caps and back fed and now i got 8kv on the crt and full screen but its still not right i cant find a break in the trace or a bad diode or anything it just dont make sense. i put the cable wire on and it has a hard time holding the signal and when it does i have 3 images with lines so the horiz timing is off so this jumper is not the fix. nothing burned either.:scratch2:

ctc17
10-09-2012, 09:54 PM
ohhh my dearest timmy..
I know its about the challenge, but I ebayed 5 inch tv and came up with several for $.01.
Now; if you time is worth.....say $5 and hour hmmm :headscrat

Probably a resistor, surface mouth regulator or choke that failed...

AiboPet
10-09-2012, 10:21 PM
LOL ctc17

It's the challenge...for sure. I've mentioned SEVERAL times you don't do this for the paycheck.

I was working on a similar "basket case" for a week or so.....until I got STOPPED by the realization I was NOT going to fix the focus pin on a 4.5" CRT. Now it just sits...because every set I have bought cheap THINKING I was gonna use the CRT from a broken set.....was easy to fix.

I just HATE it when the game can't be won. Its the only set I have sitting that "is" fixed....but can't find the parts. I went on to get a 6" Singer TV6U which REALLY is gonna be alot of work...and parts to get going again.

I'm gonna go ebay "5 inch TV" and see all these $.01 sets you speak of. Best deal I ever found was a REAL tiny 2" Magnavox micro AM/FM/clock I got for $1.25 once (and was PERFECT!!). Most 5" sets of varying collectability go for anywhere from $10 for the cheap chinese things...to about a hundred for something like a Sony 5-307UW, and THEN like $20 to get it to you in some reliable manner. Any $.01 set is gonna AT LEAST run you ten bucks to have it shipped....and they will treat it like a $.01 set when doing it. Even at a swap meet "in person", these cheap little sets are $5-$10, and the added benefit that some don't even know they are color sets (I got a beautiful JVC CX-500US "briefcase" that way with no power cord)

ctc17
10-09-2012, 10:56 PM
$.01 Auction, $55.64 shipping.....

timmy
10-10-2012, 06:14 AM
ohhh my dearest timmy..
I know its about the challenge, but I ebayed 5 inch tv and came up with several for $.01.
Now; if you time is worth.....say $5 and hour hmmm :headscrat

Probably a resistor, surface mouth regulator or choke that failed...

i know its junk but it helps me stay somewhat sharp and besides it dont need a flyback after all but i cant seem to find what failed, no visible burned resistors, it dont have a regulator,i am thinking one of those little green poly caps since i changed ALL the electrolytics after finding one bad one. i did get a picture and sound but the signal seem to fade in and out and had 3 images so the jumper i had done seems to be leaving out a certain part of the overall circuit, the 3 images and the sound fading. am i correct in saying that not all glass zeners test one way that some do pass voltage the other way testing in the diode test of a digital vom?:smoke:

timmy
10-12-2012, 07:00 AM
well here goes this little set needed a horiz hold pot the frequency was so far off that it showed 3 images thats what that problem was. the jumper i placed to get the boost voltage going did infact do the trick as i was never able to locate the source of that problem or break somewhere. then there was the fading signal i would get a pic and sound then it was gone that was a bad resistor subbed that and now its got 6kv at the crt,great picture, great sound with no fading and left it on for 3 hours playing . i must be out of my mind because i had found one bad cap 160v470uf and i went ahead and changed all 30 electrolytic caps, i had them all, cost me nothing. its amazing what a cheap set it is but yet produces such a clear picture.

AiboPet
10-12-2012, 07:41 AM
And now you have that "Jeeees....THAT one was a nightmare" story when someone sees the little thing on a shelf....and it's NOT in a landfill somewhere. I do have a similar little basket case like that, but that project is stopped as it needs a little 4.5" CRT I can't find (focus pin was busted off....obviously could not fix it)

timmy
10-12-2012, 08:07 AM
focus pin on the crt. it can be fixed but you have to use the smallest, thinest wire and use a 300 or more watt soldering gun and it will work and then add a longer wire to put it where it goes. you have nothing to else to do but look for another crt so try it.

timmy
10-23-2012, 12:55 PM
not that it matters much but for those who are fixing these b@w portible chinese sets be aware that a few of these sets had the same problem no or low hv 2500kv and no boost voltage and the crt wont light up. all these sets had the same thing wrong and it was easy for me after finding out with the first one that it was the horizontal adj pot, its a 5k pot but the one in there was so cheap just like the whole set but change that pot and all will work. crt has 6kv and it amazing how clear and sharp these cheap sets produce.

rpm1200
10-23-2012, 03:17 PM
Best deal I ever found was a REAL tiny 2" Magnavox micro AM/FM/clock I got for $1.25 once (and was PERFECT!!).

If you have a picture of the Maggie could you please post it? Thanks! :banana: