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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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6th Jan 2021, 5:32 pm | #1 |
Tetrode
Join Date: Dec 2020
Location: Chelmsford, Essex, UK
Posts: 61
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Caution: moving radios around the workshop
I think this brief warning is more aimed at newbies, such as myself, than those with experience....
I was approaching the end of restoring a Murphy U472. I had managed, with help from the forum, in getting it not just working but more selective and sensitive on FM than my A482. My smugness and self back-patting dried up when I switched on the set last night- Only one station tuneable on FM and one on AM. The sound was very, very quiet and distorted. Real men do not cry or eat quiche, so I did neither. Instead I looked at the schematic. I might as well have looked at a map of Holland for all the good it did me with the radio. I got to assuming all sorts of horrors involving purchasing rare valves or transformers. A visual study quickly revealed that one of the output transformer tags had broken clean off and was *just* contacting what was left of the terminal, allowing some audio to leak through. An easy, but perhaps avoidable fix. THE ANALYSIS: I had been moving the chassis from bench to shelf every time I have worked on it. I think that moving the chassis dozens of times during the process has stressed this tag somehow and finished it off. LESSON LEARNED: minimise movement of these old radios, especially out of the cabinet. Maybe leave the chassis on the bench for the whole process if at all possible. I offer up my own clumsiness to the forum. |
6th Jan 2021, 5:41 pm | #2 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,799
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Re: Caution: moving radios around the workshop
Rather a lot of materials become more brittle in their old age, and this is matched by a number which go soggy, lose tension or even turn to sludge. Everything becomes more delicate.
It reminds me of a taxation definition.... If it goes hard as it spoils, it's a cake, if it goes soft, it's a biscuit. We get both in every box. But in moving heavy radios around, be careful of yourself. Radios are easier to fix on a DIY basis. David (AR88 owner)
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6th Jan 2021, 9:44 pm | #3 |
Dekatron
Join Date: Nov 2006
Location: London, UK.
Posts: 3,496
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Re: Caution: moving radios around the workshop
I’m happy it ended well for you, Xyence!
It can be a good idea to put some temporary strain-relief measures in place when repetitive tugs and bursts of tension are going to put fragile structures under stress. Good old cable ties work well and can easily be snipped out again. It can become instinctive over a while to spot where this might be an issue. Happy outcome for you, and a pleasing result for us to read.
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Al |
7th Jan 2021, 9:59 am | #4 |
Dekatron
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 7,548
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Re: Caution: moving radios around the workshop
It's always best to avoid disturbing as much as possible with old electronics especially were tags and tagstrip is involved. More than once I've had tags detach themselves from transformers even when being careful. It is often found that component leads are wrapped around tags...even worse when more than one component shares the same tag. I generally cut the component lead at the tag and then just solder the the new component lead to the tag. There is nothing wrong with making a 'surface' bond like that.....generally there is no movement once components are fitted and whilst it might be frowned upon by purists, in practice it was done typically when any repair was carried out even back in 'the day'. If the new soldered joint is good, there will be no problem.
With old electronic equipment be it radio, TV, amplifier, record player or tape recorder, tags and tagstrips are likely to be getting brittle and the less heat and disturbance to these connections, the better.
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7th Jan 2021, 11:12 am | #5 | |
Tetrode
Join Date: May 2019
Location: Limoges, France.
Posts: 60
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Re: Caution: moving radios around the workshop
Quote:
Peter F4VSA |
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7th Jan 2021, 11:38 am | #6 | ||
Heptode
Join Date: Jun 2017
Location: Southport, Merseyside, UK.
Posts: 646
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Re: Caution: moving radios around the workshop
Quote:
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7th Jan 2021, 12:52 pm | #7 |
Tetrode
Join Date: Dec 2020
Location: Chelmsford, Essex, UK
Posts: 61
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Re: Caution: moving radios around the workshop
I really appreciate the warm welcome I have received on this forum.
It is forums such as this, and similar content on YouTube, that allows the uninitiated the chance to enter a new hobby. Add in gumtree, eBay and Facebook marketplace and the chance for more beautiful old equipment to be restored increases. Thanks for the words of wisdom. These old chassis may look like military-grade tank components but I am learning the truth. I had to look up the AR88. At 100lb that is a radio that could launch my lower disks into orbit |
7th Jan 2021, 1:15 pm | #8 | |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,385
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Re: Caution: moving radios around the workshop
Quote:
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7th Jan 2021, 1:41 pm | #9 |
Hexode
Join Date: Feb 2014
Location: Southampton, Hampshire, UK.
Posts: 419
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Re: Caution: moving radios around the workshop
Hi , "where did that wire come from?" used to plage me untill I learnt that the best thing to do in reparing things is to build some type of jig to hold the chasis so that it can be turned upside down and moved without stressing anything. Very important for things that "hinge" apart with connecting wires.
Pete |
7th Jan 2021, 3:42 pm | #10 |
Dekatron
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,809
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Re: Caution: moving radios around the workshop
I have just been working on an Armstrong 626 hifi receiver for many weeks and it constantly needed to be turned over to access boards and components on both sides. There's no way around that, I must have turned it over dozens of times. Also, I had to constantly swing PCB boards over, straining connecting wires (150 degree bends!) to access both PCB track and component sides. And yes a wire did break at a PCB terminal, but I quickly found it. Sometimes there's no alternative to moving a piece of kit around, it goes with the job as they say. But once you know that damage can occur as a result, you're more careful and more inclined or able to look for the obvious broken wire, whatever, when something unexpectedly happens. My worktop is covered with a piece of 'no snag' carpet that cushions and protects components and pressure points.
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7th Jan 2021, 6:30 pm | #11 |
Pentode
Join Date: Jul 2020
Location: Borehamwood, Hertfordshire, UK.
Posts: 216
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Re: Caution: moving radios around the workshop
I have now finished all the work on my Champion 784M Radio and given it a six hour stress test and to stop more heat damage to the case i have fitted in the top a piece of strong cardboard treated with silver Hammerite paint and in the bottom some black heat proof oven liner under the side with the mains dropper and hot valves
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7th Jan 2021, 7:04 pm | #12 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,145
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Re: Caution: moving radios around the workshop
Beware the Mazak rot!
Probably the most damaging to vintage electrical equipment. It not only rots but buckles and twists and as far as I know there is nothing you can do about it. It was dangerously brittle when new. Old style 78 RPM gram motor cases, turntables and pick up arms are very vulnerable. It's a frustrating nuisance. John. |
7th Jan 2021, 8:17 pm | #13 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,799
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Re: Caution: moving radios around the workshop
An exemplary post, John. A good description of Mazak castings without a single rude word! I don't think it's ever been done before.
For the OP's benefit, it's a proprietary name for a mixture of metals optimised for cheapness and ease of diecasting. It has a very low melting point. But it's once it starts to age that it twists into pretzel shapes, crumbles and does other un-metal-like things. Strength, resilience and longevity never got a look in. Any good description of the stuff is going to work its way through a fair amount of the Oxford English Dictionary of Obscenities. David
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
7th Jan 2021, 9:24 pm | #14 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,923
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Re: Caution: moving radios around the workshop
I think another polite phrase as used on tuning caps is, "Monkey Metal". Normally appertains to stuff made from cast.
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9th Jan 2021, 7:46 pm | #15 |
Dekatron
Join Date: Jan 2006
Location: Ramsbottom (Nr Bury) Lancs or Bexhill (Nr Hastings) Sussex.
Posts: 5,814
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Re: Caution: moving radios around the workshop
Yes MM, as per the recent thread by Kestrelmusic "Re Akai 4000D Cam" 29/12/20 [p3*]. I was always a fan of this cleverly designed and economic Tape Recorder but having that very crucial part constructed from a sort of amalgam was definitely a mistake. I would give Akai the benefit of the doubt though. I think they and other manufactures were aiming at an affordable product but I suspect they weren't necessarily going deliberately for short term results, just unfortunate. All the other parts were of a good quality for example! A case of "spoiling the ship" perhaps but ok if you were lucky and/or careful with the controls!
Dave W Last edited by dave walsh; 9th Jan 2021 at 7:53 pm. |