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Simon Johnston
United Kingdom
6123 Posts |
 Posted - 30/09/2012 : 20:18:51
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Not MMM specific, not even MG specific, but would anyone have any suggestions for a replacement switch and bulb holder for a 1960s map magnifier like the one in the photo. The one I have has a dodgy switch with the bulb holder (12v 2W) soldered to it in a rather precarious way and I'm trying to work out what sort of switch and bulb holder were used originally. From the photo the switch looks to be a regular toggle switch but I can see no evidence inside the unit of how the bulb was mounted.
Anyone got one lying around that they could check for me?
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David R
United Kingdom
289 Posts |
Posted - 01/10/2012 : 00:17:20
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Simon
Your picture brought back memories of a mis-spent youth (and middle age!) poring over OS maps at dead of night in a variety of 60s/70s/80s rally cars driven at suicidal speeds over minor roads in the north of England and Wales. What you have is a genuine Poti,an essential tool for any self-respecting rally navigator until it was replaced by the superior Don Barrow light.
I can't really answer your specific questions,except I recall we replaced the bulb by something more powerful (probably 5W screw-in) and sometimes added a second bulb holder and bulb. I don't remember particular problems with the bulb holder which I think was soldered to the casing,and the switch and twin pencil holder look original. Often the flex was replaced by a coiled type telephone flex which withstood shocks better and prevented the plug leaving its socket at crucial moments. The Poti had a cut-out through which you could insert your Garford or Don Barrow romer (on a string round your neck)
so you could measure distances on the map and shout instructions to your driver accordingly.Your Poti also got pretty hot which was no bad thing at a Control on a frosty night.
I attach 2 photos which hopefully can just show a Poti in use. I happen to be the driver in both cases,but I did my fair share of navigating.
David
J 3355
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David R
United Kingdom
289 Posts |
Posted - 01/10/2012 : 00:45:36
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Simon
Just can't get the second photo to load.
David |
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Simon Johnston
United Kingdom
6123 Posts |
Posted - 01/10/2012 : 07:40:15
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David,
Many thanks for your reply. I have to confess the photo isn't of my actual Poti but one I found showing the correct switch. Mine is slightly more used looking! But I'm baffled as to what sort of bulb holder and switch were used originally as there's no evidence inside it of any soldering or other methods of fixing the bulb holder. But it's a nice period piece and I quite like having the cutaway for access to the map with romer and pencil if necessary. I'm passing it on to my daughter to use in the left hand seat of the J2 and as she's left handed, light escaping from the cutaway isn't an issue for me when driving. |
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Alan Bertram
United Kingdom
199 Posts |
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David R
United Kingdom
289 Posts |
Posted - 01/10/2012 : 11:11:03
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Simon
Having another try in the morning light.From what you say the bulb holder may not have been soldered to the body. It was only a thin metal strip with a hole into which the bulb screwed and earthed and a spring contact for the live wire. It may have hooked in some way over the top rim whichhad a plastic strip covering the join between the lens holder and the main body.
David
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Simon Johnston
United Kingdom
6123 Posts |
Posted - 01/10/2012 : 12:14:04
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Alan,
Good suggestion and in fact I'd alrady been in touch with Don Barrow over the weekend and he wasn't able to throw any light on it (no pun intended!)
David,
What you say sounds plausible as I can't see any sign of anything having been fixe to the body of the Poti so the bulb holder may have been hooked on the inner rim. I shall investigate further. Thanks |
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David R
United Kingdom
289 Posts |
Posted - 01/10/2012 : 18:35:17
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Simon
Just had another thought. Could the bulb holder bracket have been clamped to the body by the switch itself? I do not recall much wiring inside the Poti,because there would have been the risk of pulling a wire off as your hand and Romer could be to an extent inside the Poti body. I seem to remember now that switch body and bulb holder were effectively one unit and certainly did not intrude in your line of vision through the lens.
David |
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Simon Johnston
United Kingdom
6123 Posts |
Posted - 01/10/2012 : 19:29:34
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David,
Sounds plausible - that would certainly explain why there's no evidence of any bulb holder being directly mounted to the body of the Poti. I'll have an online hunt for a suitable holder that could be retained by the switch.
Many thanks. |
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Simon Johnston
United Kingdom
6123 Posts |
Posted - 01/10/2012 : 19:52:27
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Good call, David. I reckon this is just the job. It would be easy to make up a ring with a lug to fit this that was secured by the switch itself.
Many thanks
Simon |
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