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Hints, Tips and Solutions (Do NOT post requests for help here) If you have any useful general hints and tips for vintage technology repair and restoration, please share them here. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 30th Aug 2007, 12:11 pm   #61
Chris55000
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Default Re: Vintage radio safety

Hi!

Allow me to clarify a bit - the points I make are based on my personal experience!

1) Mains Transformers

It has been my experience with several sets - Pye among them - that once a mains transformer has lost a substantial amount of its impregnation they do have a tendency to run very warm afterwards and worse, I've known substantial voltages develop on the chassis w.r.t. earth once mains transformers are excessively heated - whilst this is really down to the the transformer's designers/makers rather than a repairer I feel its only prudent to warn others there's an increased possibility from shock risk with an unearthed chassis once a transformer has been overrun, even for only a short period of time!

2) Baretters

I certainly have come across these things and agree you can remove the holder and fit an adaptor with a dropper resistor etc., there's still the problems with ventilation and making the adaptor safe and reliable! Admittedly this was easier with RS "Sections" but I've not seen these for years now!

3) Flaking ceramic coating on exsisting droppers

Again my experience has been that its only to easy to nick or damage an exposed element accidently unless you're very careful and for this reason I
recommended against trying to reclaim a set with a badly flaky one!

4) Capacitive Droppers

"Motor Run" capacitors will handle the ac current in an heater chain, its just these are physically large and there may not always be room for one! A metal-cased type for single-hole mounting would be the safest way of using one as the connections would be wire leads/tags below the chassis!

Whilst most chappies like myself have had many many years experience there'll always be younger chaps or those with less experience of potential hazards in old sets because they're new to Vintage Restoration, and I also have in mind other members of a restorer's family who may not be technical and I had their safety in mind as well!

Chris Williams
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Old 30th Aug 2007, 1:09 pm   #62
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Default Re: Vintage radio safety

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I also have in mind other members of a restorer's family who may not be technical and I had their safety in mind as well!
I think that's very important
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Old 30th Aug 2007, 1:57 pm   #63
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Default Re: Vintage radio safety

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Originally Posted by Richard_Newman View Post
I'll just add my own views based on 40 years experience. Firstly flaking droppers. My Pilot Little Maestro has virtually no ceramic left on the dropper. It's been like that for as long as I remember and I've had the set since 1968. It is still working fine.
There were some droppers that had exposed wire elements and no ceramic in them at all - my forgettory fails me here as to which ones.
I cannot understand why that would be a problem if the back cover was intact.

At the moment, most post-war radios are quite cheap in monetary terms. That might not be so always.
Depending on public whim, even a lowly 4-valve B9A U-series job might become valuable, and we'll regret the shortcuts and bodges (or some of the "safety" modifications) that were done.
I am not saying that the end product should not be safe; but please respect originality and the fact that it was probably designed by a respected and well-paid team; we should think twice about adopting a "we know better" stance.
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Old 30th Aug 2007, 2:51 pm   #64
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Default Re: Vintage radio safety

Yes, here's a fine example of a mains dropper in an Ekco ADT95, pretty much in its original state and mounted about half an inch from the set's back... seems to me all that matters is that the wrong people don't get to probe around in its vicinity. If I were expecting uncontrollable visitors I'd certainly have to amend various things around the household, though I think the peril of their getting crushed would be a more urgent one than any electrical considerations.

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Old 30th Aug 2007, 5:18 pm   #65
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Default Re: Vintage radio safety

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Originally Posted by Mike Phelan View Post
I am not saying that the end product should not be safe; but please respect originality and the fact that it was probably designed by a respected and well-paid team; we should think twice about adopting a "we know better" stance.
Indeed. Sometimes, however, that 'well-paid team' were working within the constraints of what they knew about to the best of their knowledge. Who'd have thought that polychlorinated biphenyls (PCB) would pose the danger that they do? When I was an apprentice electrician, this 'Pyrochlor' (a form of PCB) was considered the be-all-and-end-all of transformer insulating coolants!

Ten years later and I find myself donning disposable overalls and full face-mask and helping eradicate the stuff (now considered nasty beyond comprehension) from BBC transmitting stations...

I have a Bush DAC90 waiting in the wings. I'm not worried about the ceramic dropper (the back of the set looks surprisingly unburned as well) or the fact that it has a live chassis, but I shall certainly try to find a substitute for the flaky asbestos surround!
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Old 31st Aug 2007, 7:39 am   #66
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Default Re: Vintage radio safety

I agree, Russell. In the light of further experience over the centuries/decades/years (like mercury, phosphorus, smoking, asbestos) we have gained useful experience and avoided or controlled harmful substances.

My stance was just that we should avoid "tilting at windmills" - destroying flaky droppers or destroying or cannibalising AC/DC sets.

We have a great advantage here that the collective experience and knowledge of this forum is possibly the greatest on our planet, and certainly greater than any official body who may have vested interests.
Just my opinion; there is no "right" one, as many will agree or agree, but we are all individuals. An interesting and useful thread.
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Old 31st Aug 2007, 4:36 pm   #67
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Default Re: Vintage radio safety

Hello.
I wonder just how far we can go with this discussion.
We are now far too safety orientated, often people say that the country has gone too far with health & safety. My own feeling is that some aspects of improving health & safety were needed but in the respect of vintage radio & TV common sence prevails.
I always fit 1 or 2 amp fuses in the plugs of my Radios & TV set (you can get plug top fuses in this amperage) and always replace mains filter caps with modern types.
With AC/DC sets I always ensure the chassis is at neutral and any removable non polarised plug is held in with a dab of hot melt glue.

Mains droppers are fine even with their ceramic lost, the back cover will stop fingers entering the set! No back cover then make one!

Mains transformers, I've NEVER had a tranny with a leak to earth on older equipment, I have with modern stuff, and you can always connect an earth to the chassis and use an RCD if you are really paranoid.

I could go on but I won't.

I have a 1972 VW1302S. It doesn't have servo brakes, power streeing, halogen lights or rear seat belts so should I stop using it as its not as safe as a 2007 car? No I don't think so.
Trevor
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Old 1st Sep 2007, 9:20 pm   #68
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Hi
Slightly OT, but following on from Trevor's point, an article in Practical Classics a month or two back agrued that older cars are more safe as the driver is not in any doubt of the prevailing conditions and adjusts his speed and driving accordingly, whereas a modern car removes any feedback and coccoons the driver.
This could be analogous to our interest - we know the linitations of old equipment, so (say) would never leave things on while we go out, whereas modern equipment is assumed to be so safe it can be left on, with (very occasional, I admit) disastrous consequences.
As this thread is saying, it's all down to well-informed common sense - some things, such as filter capacitors, have improved immesurably over the years, and it makes perfect sense to upgrade the component. Others, like droppers, would need huge modifications to be replaced with modern technology, and might not be safe in any case!
I must admit to sometimes looking at (say) a dual-standard hybrid colour television and thinking 'how did they ever think this would work in a domestic environment?' But work they did....
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Old 1st Sep 2007, 10:51 pm   #69
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A very valid Thread for this Forum - so I'd just like to pop in my hap'penny worth.

My take on this is that it's a matter of judgment and risk assessment.

If I can assure myself that the item in question will only ever have my hands on it, then I'll probably leave it alone. However, if there is something that is clearly a hazard - or may easily become one - and depending on the possible consequences of the hazard, I will probably make some reversible changes. Things that springs to mind are:
(a) single-pole switching of the incoming mains supply - I will replace this by DPDT switch;
(b) Exposed mains wiring connections beneath the chassis - I'll add additional insulation - like heat-shrink;
(c) The wiring method to panel-mounted mains fuse holders, where it is possible - when replacing a non-blown fuse with the mains supply not disconnected - to receive a full mains supply shock;
(d) Colour coding / mains wiring. If its red/black, or black/white - and 230-Vac powered - I will replace it with blue / brown. And this includes internal to the set as well;
(e) The method of mains supply / switching / fusing whereby the incoming mains "sees" the fuse first - then the switch. I'll re-wire this so that the incoming mains "sees" the switch first. (A lot of USA equipment is wired fuse first. I understand the thinking here - the fuse protects the switch. I just feel a lot more comfortable knowing that when I switch it off, apart from the mains at the DPDT switch, the mains is disconnected to the rest of the set after the mains switch).

As for AC / DC powered equipment, I currently own none. But should such an item come my way, I'd have no hesitation whatsoever of making changes such that the item can only be powered from a dedicated isolation transformer - probably installed external to the item, in an earthed metal case, suitably fused and switched.

I always maintain a record of any changes (safety-related or otherwise) that have been made to any item and keep a record of this with the item and in the workshop log-book.

Al / Skywave.
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Old 2nd Sep 2007, 2:23 pm   #70
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Default Re: Vintage radio safety

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I always maintain a record of any changes (safety-related or otherwise) that have been made to any item and keep a record of this with the item and in the workshop log-book.

Al / Skywave.
''Workshop Log-book'' ... now you've set the cat among the pigeons.

I scribble numbers and sketches etc. as I work through a repair or restoration but these are never preserved for anyone's benefit in the future. How many of us have re-visited a set and wondered what we did to it the first time around!

It occurs to me that I really should maintain a log of everything I do with the old sets I'm currently acting as custodian for. On reflection it seems that the log is every bit as important and useful as having the set working. We owe it to those who will look after these sets in the future and of course the positive impact on the safety of all concerned should not be underestimated.

I wonder how many of us actually keep detailed log of everything they do during a repair or restoration.

Colin
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Old 2nd Sep 2007, 2:59 pm   #71
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Hello,

I am in the Electric Motor trade, and the motor run capacitors that we use are often passing several amps (quite a few in the case of a 2.2Kw motor) continuously and are absolutely perfect for using as capacitative droppers in Radio's and the like. (and it is very rare when one fails and when one does they are designed to go open circuit)
Capacitive droppers are not safe by any means,they may be ok for a motor that wont mind the spikes,harmonics,rf that a capacitor eagerly will let through.Another point is a capacitor is frequency AND WAVEFORM dependent,,I would never,never use one as a dropper in a radio that I care for. There were only one or two manufactures that tried this idea,may have been ok when the AC mains was a clean sine wave,and no rf.
A capacitor feeding heaters would be almost a dead short at RF!
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Old 2nd Sep 2007, 3:14 pm   #72
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Originally Posted by Skywave View Post
A very valid Thread for this Forum - so I'd just like to pop in my hap'penny worth.

My take on this is that it's a matter of judgment and risk assessment.

If I can assure myself that the item in question will only ever have my hands on it, then I'll probably leave it alone. However, if there is something that is clearly a hazard - or may easily become one - and depending on the possible consequences of the hazard, I will probably make some reversible changes. Things that springs to mind are:
(a) single-pole switching of the incoming mains supply - I will replace this by DPDT switch;
(b) Exposed mains wiring connections beneath the chassis - I'll add additional insulation - like heat-shrink;
(c) The wiring method to panel-mounted mains fuse holders, where it is possible - when replacing a non-blown fuse with the mains supply not disconnected - to receive a full mains supply shock;
(d) Colour coding / mains wiring. If its red/black, or black/white - and 230-Vac powered - I will replace it with blue / brown. And this includes internal to the set as well;
(e) The method of mains supply / switching / fusing whereby the incoming mains "sees" the fuse first - then the switch. I'll re-wire this so that the incoming mains "sees" the switch first. (A lot of USA equipment is wired fuse first. I understand the thinking here - the fuse protects the switch. I just feel a lot more comfortable knowing that when I switch it off, apart from the mains at the DPDT switch, the mains is disconnected to the rest of the set after the mains switch).

As for AC / DC powered equipment, I currently own none. But should such an item come my way, I'd have no hesitation whatsoever of making changes such that the item can only be powered from a dedicated isolation transformer - probably installed external to the item, in an earthed metal case, suitably fused and switched.

I always maintain a record of any changes (safety-related or otherwise) that have been made to any item and keep a record of this with the item and in the workshop log-book.

Al / Skywave.
There are some points that I would not agree with.Safety depends on how the set is used or misused.Sets made years ago were made to strict safety standards,(mostly) to modify these to present flimsy practices could render the set unsafe.
DP switches are frowned upon,unless the set is live chassis and fed by a 2 pin reversible plug,when DP switch must only be fitted.
The safety of SP switch was covered in a previous thread.
As for exposed wiring,well,are you trying to use it outside its case?
Red and black should always be used,if blue and brown were used then replace with this.And yes, fuse certainly before switch if its DP Ive seen too many switches caught fire or blown apart!
I would not be able to enjoy my collection if I were to apply indescrimate modifications or to fool myself that the set would be safer in doing so.
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Old 2nd Sep 2007, 4:18 pm   #73
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Default Re: Vintage radio safety

As a very general rule, I will not tolerate anything that can easily lead to accidental hazard i.e I won't operate (outside servicing) equipment with covers removed, damaged knobs (etc). Basically if it's a hazard to me or anyone else in a moment of absent mindedness I'll positively make sure it can't have power applied.

On the other side though, I would never re design elements of a set in my collection to conform to the whims of modern "elf 'n' safety" culture.
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Old 2nd Sep 2007, 8:16 pm   #74
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Default Re: Vintage radio safety

Re: Capacitive Droppers.

They were used in one TV that all the TV repair people here know of. The BRC 1580 Chassis. Sets such as the Ultra 6805. This was a 12 inch portable from the Early 70s, and the valves had their heaters supplied by a large capacitor, I think it was 4.33uF.

These took ages to come on sometimes, and were susceptible to Mains variations. In the end, BRC issued mods to eliminate this. Still a lot about though - I've got 2! Both unmodified. One works, one smokes and I haven't yet had the courage to find out why.

They are used in Radios to reduce the heat of a dropper, and the details are here:

http://www.vintage-radio.com/repair-...per-calcs.html

Like many things, it depends where you use it and how safetly. I generally don't, but I know that some people do. I hope those that do remember to be CIVIL about it.

As far as safety in general goes, it depends on whether the set is for me or for someboby else. But I always put a sheet with the set if it is for somebody else, explaining some basic facts, like Unplug when you're not in or in bed and for God's sake don't use it when you're not around. I have had one comeback, but that was when a set got knocked off a table and then tried to get me to fix it for nowt! I shant type what I said...

For Safety, read Common Sense and you can't really go wrong.

'Elf 'n' Sefety' types can.....

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Old 2nd Sep 2007, 9:51 pm   #75
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Default Re: Vintage radio safety

I do. And it has been very handy on more than one occasion. It started out as an old excercise book, but these days I use the PC. Many of them end up as reports on Paul's "other" site.
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Old 2nd Sep 2007, 9:52 pm   #76
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For Safety, read Common Sense and you can't really go wrong.
Steve P
I know the reasoning behind that comment and to an extent I agree with it.

The "fly in the ointment", though, is that your and my definition of "common sense" on these matters - as "knowledgeable people" - is not the same as that of the "uninitiated". Hence the "all-embracing Safety Regs." that try to make a "one size fits all" approach - which, of course, drives the knowledgeable (read: you and I) crazy in its apparent pettiness!

Al / Skywave.
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Old 2nd Sep 2007, 9:56 pm   #77
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''Workshop Log-book'' ... now you've set the cat among the pigeons.
Colin
Well, then so be it. For myself, I call it professionalism.

Al / Skywave.
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Old 2nd Sep 2007, 10:05 pm   #78
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Indeed. Sometimes, however, that 'well-paid team' were working within the constraints of what they knew about to the best of their knowledge.
Yes - and probably also had constraints imposed from TIME and COST considerations. In the real commercial design world, these necessary "evils" do not make comfortable bed-fellows with quality nor issues like safety.

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Old 3rd Sep 2007, 9:12 am   #79
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G8DLG - am I missing something here. I have had 35 years experience of repairing radios, etc(admittedly for 22 of those I worked mostly on Car Audio) and do not know why DP switches are 'frowned upon' Personally I feel that its' wiser to isolate BOTH sides of the mains with the set switched off.* As to the fusing question I do go along with the 'fuse before switch' approach

* I currently have two Bush VHF41s to repair. These were first produced in 1954, are for AC Mains only, and were fitted with DP on/off switches from new.
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Old 3rd Sep 2007, 11:51 am   #80
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Default Re: Vintage radio safety

Hi
I think we've reached a consensus - we need to use educated common sense. We can argue the niceties of switching, fuse placement and capacitive droppers - we all have opinions on these - but in the end no-one on this forum is suggesting anything that might render a set, in their well-informed opinion, unsafe. If anything, a set restored by one of us will be better, safety-wise, than it was when it left the factory.

I think a good point has been made above - we cannot just assume an item will always be used by the same person (even one of us!). I think we need to allow that anything we repair or restore might one day end up in a 'normal' house. For that reason we need to make sure all our work is to a satisfactory standard. As I type this, I'm thinking of a working radio at home with a slightly damaged back cover...must put that on the 'to do' list!
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