BRC 1500 with different identity

[its ur aerial]

The Label on the back dates it to 1972,` L` same as the Car reg. Renters also absconded with TV`s and especially VCR`s, possibly less so at Granada they were a bit more fussy who they rented to.
Ken, G6HZG.

[bionicmerlin]

Just a update.
Thanks for the info Ken . I have made a note in the back of the set of the date.
Rich . I did the tuner repair with the springs but putting them on the outside didn’t feel quite the same as my other sets , so done the more complex repair with soldering some filed down washers.
I do have some minor problems that speed things up if anyone can help.
Slightly ragged verticals on the test card.
I did try a NOS rectifier tray . As was mentioned on some old note I found by John (HCS) but no change.
Second . Top linearity control at one end. It appears pot has gone low value.
Third thing tuning drifts from one day to the next. Could that be the grease and if so when I clean it off do I have to put fresh grease on or not.
Other than that things look pretty good
Thanks everyone so far Andy

[Restoration73]

I always repair the UHF mechanical tuner bars using a high temperature iron and high
melting point 40/60 solder, which is a lot harder than 60/40. It is also ideal for dropper
resistor tags.
i have two books written for the Thorn Television Rentals in-branch training course given
to me by the author, who was their head of training. These are dated 1980 and it is made
clear "the 1500 is the last receiver to incorporate valves and fast becoming obsolete" !

[slidertogrid]

I clean the grease off, clean the rotor where the springs contact and then clean and polish the tarnish off the springs. Slightly re tension if you think necessary then just a very light smear of petroleum jelly (mainly to stop the springs from tarnishing again rather than lubrication) .
If the pot has changed value I would replace it then check any resistors in the circuit around the pot before looking further.
Ragged verticals could be a little harder to track down, check the dag earth first, is the line hold central and solidly locked?

[its ur aerial]

[QUOTE=Restoration73;1495238]I always repair the UHF mechanical tuner bars using a high temperature iron and high
melting point 40/60 solder, which is a lot harder than 60/40.

That's a very valid point, I would endorse that.
Ken G6HZG.

[bionicmerlin]

Thanks everyone I will take that onboard.
The dag earth was probably non existent. I got that sorted now giving the spring a light sanding and re tensioning it. It’s made no difference to the verticals . The line hold is spot on roughly in the middle.
What ever I have done has thrown the hight right out . After resetting the hight I now find the top linearity is ok.
I will get on with the tuner next . Andy

[Heatercathodeshort]

Don't forget to check the video coupling capacitor C37 I believe, 64uf [use a 100uf]. This can cause all sorts of odd effects when leaky which it usually was. Granada disposed all of their ex rental sets through bulk trade outlets. They were usually in a terrible state when finally taken off rental. off. John.

[bionicmerlin]

John . Thankyou for the Info on the set. .
I did change C37 And put a new 64uf in . Is that acceptable or should I upgrade to 100uf.
IT made no difference .
I did take a picture ,not very good as my workshop is a bit sunny.
The picture is acceptable to me but ideally could be better. The picture is a bit blotchy. I take it it’s the tube . And may get better with use. Andy

[bionicmerlin]

I think I probably have gone as far as I can go. I still have the raged verticals . Probably not so bad or I have got used to it. Tuner has now been cleaned of grease and the picture has got better with use. The linearity is better than on the picture as I took that a few days ago and I have improved on it . The picture is better than the photo as my camera doesn’t like CRTs Andy

[slidertogrid]

The tube will get better with use if you run it with max brightness you may speed the up the time it takes. In stubborn cases I have run the tube heaters temporarily on a 20% boost transformer, that usually does the trick and the improvement lasts once the heaters are returned to the heater chain.
As far as the ragged verticals are concerned try adjusting the AGC and backing off the contrast a little.

[bionicmerlin]

Slider.
Thanks for your info.
I did try backing off the AGC and contrast. It’s made no difference. I have had the set running for a few hours this evening. The picture has come up pretty good after giving it some run time .
I’m more than happy how it is working now so I will settle for how it is . Andy

[ms660]

I remember that effect on the verticals in a TV once being caused by poor positioning of the CRT's cathode lead from the video amplifier.

Lawrence.

[Hybrid tellies]

Originally Posted by ms660

I remember that effect on the verticals in a TV once being caused by poor positioning of the CRT's cathode lead from the video amplifier.

Lawrence.

Good point Lawrence and this has jogged my memory. After doing any repair to a 1500 we would always coil up the video feed wire to the CRT base, I think it was a white lead, otherwise you would get also sorts of strange affects such as pattering, wobbly and ragged verticals etc if that lead went any where near the IF stage.

[bionicmerlin]

Thank you both . I did try repositioning some wires but I will double check Andy

[Heatercathodeshort]

Originally Posted by ms660

I remember that effect on the verticals in a TV once being caused by poor positioning of the CRT's cathode lead from the video amplifier.

Lawrence.

I'll second that. I also used to fold the cathode lead to prevent it getting close to the scan coils and wiring. John.

[bionicmerlin]

Thank you all for that info.
I have done what you said and I would say it’s now about 90% better.
Thanks everyone who’s helped on this TV Andy

[ms660]

When I encountered that effect it was usually stray coupling between the cathode lead (which has full composite video on it) and the line sync/oscillator stage which includes stray coupling via the valve.

Lawrence.