BBC Repair Shop - Dangerous Practice?

[redelitev6]

It's a T.V. show made for our entertainment , just relax and enjoy 

[aaronjb]

It's a T.V. show made for our entertainment , just relax and enjoy 

I think Lizzie would have been a regular on Points of View; "Angry of <town>"

[Lizzie Zoom]

It's a T.V. show made for our entertainment , just relax and enjoy 

I think Lizzie would have been a regular on Points of View; "Angry of <town>"

Funnily enough aaronjb my father's side of the family were from Tunbridge Wells and certainly did voice their opinions.  So that could be the classical explanation about me, "Lizzie, Angry of Tunbridge Wells"

[Nick W]

It's a T.V. show made for our entertainment , just relax and enjoy 

I think Lizzie would have been a regular on Points of View; "Angry of <town>"

Or from the internet: you're doing that WRONG.
Wait a minute......

[Rods2]

Because of the high voltages with valve equipment nobody should be attempting to repair them unless they know what they are doing. Old valve CRT TVs have plenty of killing zones including the chassis being used for the live mains supply distribution in many 1960-70's models.

Old electrolytic capacitors used in high voltage applications can fail with a nice pop, not that we used to mimic that as apprentices by connecting them to a high variable voltage PSU with the polarity reversed so as we wound the voltage up then went pop & spewed their guts out of the aluminium can, oh no. These were tea break or lunchtime 'experiments' when we were unsupervised by our instructors as part of our unofficial hands-on leaning course on what makes components fail through heat, fire or mini explosions & ideally all three. Convincing the thickest apprentice in our year that the 10A transformer short circuit test where we all had to wind one, that it was a 100A test worked very well in cooking the transformer, wire wound rheostat & an elbow leaning on the AVO 10A cutout button meant that was fried as well. Standard punishment was where we started a 7:40 am except on collage days which started at 9:00, the guilty & caught had to go to work & then on to college. It became an almost standard routine for him.

I'm sure Ron would have enjoyed teaching us.

[dave the builder]

I still have a hand crank Megger (now replaced with modern electricary battery one)
must give myself a 1000v insulation resistance test when I find it from storage 

[Bigron]

Actually, Rods2, I was the one who applied a high reverse voltage to a small electrolytic - maybe 10uF -  and advised my students to take cover.....within seconds there was smoke and a projectile of its innards across the room!
This was, of course, under the mantra of "don't try this at home, children".
As you will understand, it was to demonstrate the folly of placing an electrolytic capacitor in a circuit the wrong way round.
One demonstration is worth a thousand boring words!

Ron.

[Tony H]

Having a poke around our telly back in the 70's when I was about 14 to see if I could get it working under instruction from my Dad I discovered what "live chassis " meant got a "hell of a belt" didn't do that again !!!

[Bigron]

The top cap connections on the older valves were always the grid electrodes, weren't they?....er, no!!!

Ron.

[Lizzie Zoom]

Because of the high voltages with valve equipment nobody should be attempting to repair them unless they know what they are doing. Old valve CRT TVs have plenty of killing zones including the chassis being used for the live mains supply distribution in many 1960-70's models.

I learnt that by listening to the adults in the early sixties, and that is one reason why I was / am so concerned about how the "expert" in The Repair Shop treated the work to be done on the wireless chassis he removed from the wooden cabinet.  He simply put it, and the record deck, on his work bench, without any precautions, connected the old wires up, plugged it in and blew the fuses of the Repair Shop!  I was taught in my very early years not to take that type of cavalier approach if you wanted to live!   

THat approach made me doubt this "experts" understanding of safe working practices, and when he seemed to not replace the old, 70 year old, mains cables and wires,.........................well it made me shout out loud and turn to my keyboard!! .

[Kevin Wood]

The top cap connections on the older valves were always the grid electrodes, weren't they?....er, no!!!

Ron.

I'm currently working on restoring a KW 2000B. The top caps on the 6146s in the output stage certainly aren't grids. They've got about 900 volts on them.