Sony KV-1320UB trips red cutout switch
 

Hi,
Bought a Sony KV-1320UB off ebay (spares or repair), for £30, I wasn't expecting miracles, and sure enough I didn't get miracles. It instantly trips the red safety cutout on the back.
I've been testing capacitors for shorts for hours, that's where my knowledge of these ends.
Any ideas?

Re: Sony KV-1320UB trips red cutout switch
 

I've wanted one of these for many years, a stylish set.

One thing I've discovered, in the 1 second or so it takes for the trip switch to trip is that the 10ohm high wattage resistors on the power supply board get instantly too hot to tough, so something's drawing excessive current through them, but I can't seem to find the culprit.

Now I'm no expert, more an experienced amateur, I've kept my GEC / Granada set going for decades with help from this forum and a donor set to compare readings etc. If this is something beyond my level of expertese, does anyone know who I can take this to to get it going? I'm in Cardiff, but willing to travel (within reason) to get it to someone who can work some magic on it.

Re: Sony KV-1320UB trips red cutout switch
 

it's a MKII by the way, so can't find a service manual anywhere

Re: Sony KV-1320UB trips red cutout switch
 

I am not familiar with the model numbers, I prefer to see the thing in front of me then the memory starts to work. Does this set have the expensive gcs thyristors in the line output stage, if so I would check these first. It seems to be drawing a lot of current so a few meter checks should be able to narrow things down Good luck with the repair, Norman.

Re: Sony KV-1320UB trips red cutout switch
 

If its a MkII then the bits you are interested in are the same as the KV-1310UB and KV-1330UB. I've written loads on this forum about how to deal with these, it is not easy!

You'll probably find that some or all of these transistors have failed:

Chopper, Line Output, Converter, EW Output, Frame Output (x2).

They are all Sony specials and difficult to substitute. There will be a reason why they have failed too, it you don't find it you will be back to where you started as soon as you switch on. This isn't a set for the beginner or the capacitor monkey, it needs careful thinking about and a logical, step by step approach.

Read this first:

https://www.vintage-radio.net/forum/...d.php?t=151193

and this:

https://www.vintage-radio.net/forum/...d.php?p=917920

(scroll back up to the top)

If it were me I'd test the tube first. If it is good, put it in one of the many still-working examples and save a lot of time and grief. If it isn't, you are wasting your time anyway, the set is only good for parts (excluding whatever has already failed of course).

Re: Sony KV-1320UB trips red cutout switch
 

I honestly couldn't tell you, no idea sorry, I'm totally stuck with no service manual or schematic. I'm seriously thinking of paying someone more experienced to fix it, but who? no tv shops around these days. Hopefully there's someone on here that isn't too far from me.

Re: Sony KV-1320UB trips red cutout switch
 

Sounds pretty terminal then.. I'll check what you've suggested, if no joy then I might just have to wait until I find an affordable working model.
Thanks

Re: Sony KV-1320UB trips red cutout switch
 

As Studio263 has suggested, this is not going to be a cheap repair and was always difficult for the experienced Sony repair guy. Great when they are working and very reliable but nasty when they go pop.
The tube may well be weak but of course you may have a good one. Better to find a working example and keep your present one for cosmetic bits as nothing much else fails other than the bits that have!

At least it was only £30 and it's worth that if the tube is good. John.

Re: Sony KV-1320UB trips red cutout switch
 

I think that's my only option, and if I find a working (newer) 13" I'll see if I can swap the contents of it in to that cabinet.

Re: Sony KV-1320UB trips red cutout switch
 

It's not too hard to find a working 13" Sony with a duff tube. However go for the same model or else you may well find it's the wrong tube in yours. Did you see a picture of it working? If not maybe you'd be better cutting your losses as your tube could be duff.
If you want to carry on down the 1320 route I do have a few with very poor tubes, though getting one to you might be a problem as Wales is the size of, er, Wales!

Re: Sony KV-1320UB trips red cutout switch
 

Hi Glyn
No it was sold as for repair so I just took the risk (based on other such items I've managed to repair in the past.
How much do you think it'd cost to ship one down from you to me?

Meurig

Re: Sony KV-1320UB trips red cutout switch
 

There weren't many 13" ones after that, the KV-1330UB (same thing really, only the decoder circuit was different) and KV-1310UB (same chassis, different cabinet) and the KV-1340UB, whose chassis is the wrong shape. The KV-1340UB is difficult to repair too, if you get nowhere with a KV-1320UB MkII then your chances are (very) slim with a KV-1340UB...

After that they were all 14", KV-1400UB etc.

To be honest the cabinet of yours looks pretty scruffy too, there are loads of near-mint ones out there only spoiled by tired tubes. If your tube is good then its best seen as a donor for one of those if you don't fancy taking on the repair. I've fixed many of these in the past for people, but its an expensive repair so unless they are absolutely mint and the tube is perfect it makes little sense economically.

Re: Sony KV-1320UB trips red cutout switch
 

I was after one of these sets for a while, and found a worker at reasonable price, mine has a CVBS input too.
https://www.radios-tv.co.uk/wp-conte...C006020006.JPG
They come up regularly, the problem is the rare silicon used in the chopper and line output, probably best look out for another and keep this for spares. I've got a BK 467 if you want to see how good the tube is, PM me and I could test it for you.

Re: Sony KV-1320UB trips red cutout switch
 

For future reference, it might be worth looking out for the Mk.1 version of the KV-1320UB (serial number below 100,000). This has a linear power supply using a heavy mains transformer which also isolates the rest of the set for added safety. The linear power supply is much less likely to suffer catastrophic failure, unlike the Mk.II which in your case seems to have self-destructed.

The Mk.I can still go wrong, though. I have one in which some of the small signal transistors have started to corrode, their pins turning black, eventually causing component failure. Luckily, substitute replacements are available for most of the small signal transistors.

Re: Sony KV-1320UB trips red cutout switch
 

Fantastic! I'd love to try out the tube on the bk467, thanks. There seem to be a few with bad tubes around so if my tube is good then it can be kept as a donor.

Re: Sony KV-1320UB trips red cutout switch
 

Yes, the gate controlled switches. They were limited to the 1810 although the 2000 had one in the EW which rarely failed. I'm sure I have your manual, I'm back in my w\s on Monday.