View Full Version : Seeking Repair Help with Sony 5-305UW


Arcanine
04-02-2015, 08:17 PM
I'm at a loss with this little bugger. I have gone over both boards over again and again, and I can't seem to pinpoint the issue.

When I turn the set on cold all I get is a blank image and faint sound, no static on either VHF or UHF. As the set warms up, I can tweak the channel selector and sometimes get it to jump to life. Otherwise it seems to have some kind of tuner issue.

This is a bit beyond me, I have no idea where to even look. It acts like there are no stations anywhere for it to see. Sometimes it'll work better if it's sitting directly next to my agile modulator.

Anyone ever seen this before? If not, I find my self frustrated with it, and would be okay shipping it off and paying for it to be repaired by someone who has dealt with this before.

Electronic M
04-02-2015, 09:05 PM
Have you cleaned the tuner switch contacts? If not what you need to do is get at the tuner and pop the cover off to see them. Get some TV tuner cleaner or preferably a can of deoxit, and spray the contacts, work the channel knob thru several rounds, wipe the contacts (if you can) with a paper towel and repeat if necessary.

On larger sets this is often a piece of cake, but I've never done it on a small portable so I can't speak to the effort involved.

zeno
04-03-2015, 07:17 AM
Not sure on this one but.......
On late '60s Sonys IF transistors legs would rot off.
IIRC they were square shaped with with an angle cut on
one side & had flat pins. They would intermit sometimes.

Also is the pix snowy, blank white or black when acting up ???

73 Zeno:smoke:

Findm-Keepm
04-03-2015, 09:38 AM
Not sure on this one but.......
On late '60s Sonys IF transistors legs would rot off.
IIRC they were square shaped with with an angle cut on
one side & had flat pins. They would intermit sometimes.



73 Zeno:smoke:

2SC403's - replaced a few in my time. They would act up like a bad solder joint - a real fit finding them. The 2SC403A fixed that - used to get them from the early MCM Electronics - they looked like Sony dipped them after molding so they were encapsulated down the leads about a 1/16' or so. They were cheap enough - ~60 cents, so we would swap them out as a call-back prevention.

A little bit of trivia - MCM was named for the three guys that started it in 1978/79 - Mike, Charlie and Mark, IIRC. I found their 1979 Spring Catalog in my late father's stuff - all of FOUR pages! Semis, fuse lamps, grain-of-wheat bulbs, and the ubiquitous 2.5A/1KV diodes, 100/$14. Only 20 or so STK modules listed....

Arcanine
04-03-2015, 12:41 PM
Not sure on this one but.......
On late '60s Sonys IF transistors legs would rot off.
IIRC they were square shaped with with an angle cut on
one side & had flat pins. They would intermit sometimes.

Also is the pix snowy, blank white or black when acting up ???

73 Zeno:smoke:

Completely blank! No snow. Nothing, just a grey blank image.

zeno
04-03-2015, 01:00 PM
sounds like IF is out.
If the tuner usually get snow or something.
You will see contact noise changing channels if nothing else.
And it CAN be a very dirty tuner. Ive seen a few that
were totally dead.

73 Zeno:smoke:

Arcanine
04-03-2015, 01:04 PM
This might help I made a short video of what the set does from stone cold. It had been powered off for over 24 hours when I started recording.

As you can see, there is a picture on Channel 6, where I set my Agile Modulator, but the sound is very weak and the image is hard to maintain, and it has to he fairly close to my modulator.

All I get is a blank, soundless image on all the other channels on both bands.

After it warms up, static shows up on the other channels and the image clears up.

https://youtu.be/iSkkBkEJiZs

Findm-Keepm
04-03-2015, 02:13 PM
All I get is a blank, soundless image on all the other channels on both bands.

After it warms up, static shows up on the other channels and the image clears up.

https://youtu.be/iSkkBkEJiZs

What other analog channels should you be receiving? If there are none, all the other channels would show nothing. Mine acts very similarly - only channel with any sound at all is the output of my DTV converter, channel 4.

I'd check the DC voltages on the IF transistors starting with the 1st IF. Keep it on station, with the antenna and fine tune stationary. Monitor what the collector voltage does when it acts up. If there is no change, move to the next IF stage (X1, X2, X3..) Your Sound IF comes off the last IF transistor(also serves as the first sound IF amp). Weak sound on mine was restored by replacing C412 and C413, per my markings on the schematic I have. C412 couples the sound to the volume control, and C413 is the bypass for X10, the 1st audio driver.

If it is an IF transistor, the 2SA162/2SA163 cross to both the 2SA453 and 2SA455, depending on which Sony Semiconductor Replacement Handbook you use. My 1977 one shows the 2SA453 and the 1981 shows the 2SA455 as the replacement. The sound IF amp transistor 2SA323 is replaced by 2SA182.

zeno
04-03-2015, 08:03 PM
OK watched the video, that was exiting ! And informative....

A good working TV will give what we called good snow & a
nice loud waterfall sound without signal. Yours does not.
Snow should be dots without streaks & lots of contrast.
Changing channels on yours does not show any switch noise
that I can see. Everything points to IF problem.
Try freeze mist. After warm up spray some on a Q-tip then
hold it to the IF transistors one at a time. If no joy with 1st IF
let it warm up again then try 2nd etc. It may be just as easy
to change all 3 ONE AT A TIME ! I used ECG replacement with good luck
except when I worked at Sony Service, then it was OEM
needless to say.
One other thing about all early Jap sets is they were ALL very
unstable after a few years. They used crap electrolytics.
Aim to get the IF's "hot" again & deal with any instability
later.

73 Zeno:smoke:

drbock
04-19-2015, 03:52 AM
You have been tuner. It can not be cleaned or gone not to successfully. Get a parts set or two. You will need them. Nobody strips down Sony micro tuners. F you have outstanding set otherwise buy a set. Otherwise, toss your out. Next time demand to see unit working before buying. :nono::nono: