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General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc. |
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14th May 2021, 2:14 pm | #1 |
Tetrode
Join Date: Aug 2009
Location: Derbyshire, UK.
Posts: 50
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Faulty power Transformator - replacement?
Hi.
I hope this is the correct place to post this. I have an RTW volume meter and its power supply is buzzing really badly. Unfortunately, I can't seem to find a replacement on the general web so I was wondering if anyone here could point to a possible replacement? I've tried to get in touch with Schaefer but had no replies. Not even sure if they're still made. Many thanks |
14th May 2021, 2:53 pm | #2 |
Octode
Join Date: Oct 2007
Location: Exeter, Devon, UK.
Posts: 1,554
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Re: Faulty power Transformator - replacement?
Transformer troubles.
It certainly sounds as though the transformer insulation is failing., but first just check that the unit is bolted down firmly to the PCB and the laminations are firmly clamped together. Are any windings connected together on the circuit board. I suspect the use is as 100-0-100v at 9ma to feed a nixie tube display, and 8-0-8 at 200ma for the main electronics. This latter is presumably rectified and cut down to a 5 v rail through a regulator IC, such as 7805. And perhaps a negative 5v rail through a 7905. You must tell us a bit more about the circuit components around the transformer. The primary is two 120v windings, so probably connected in series for UK mains. Perhaps you can confirm. With this information, it should not be difficult to identify an alternative and any necessary mods to the PC Board. wme_bill |
14th May 2021, 2:58 pm | #3 |
Tetrode
Join Date: Aug 2009
Location: Derbyshire, UK.
Posts: 50
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Re: Faulty power Transformator - replacement?
Hi Bill.
I'm afraid you have one up on me at this point, that is... I really don't know much about these things or what is wrong or anything about the circuit. I can give you the model number : RTW 1206D 'plasma PPM display' Do you think finding a direct replacement supply unit be hard to do? |
14th May 2021, 5:10 pm | #4 |
Dekatron
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,643
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Re: Faulty power Transformator - replacement?
Have you tried RTW, Schaffer are unlikely to deal with one off quantities.
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14th May 2021, 5:19 pm | #5 |
Tetrode
Join Date: Aug 2009
Location: Derbyshire, UK.
Posts: 50
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Re: Faulty power Transformator - replacement?
Hi.
I've tried RTW too... none left in stock apparently. |
14th May 2021, 8:17 pm | #6 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,195
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Re: Faulty power Transformator - replacement?
Hi, unfortunately this type of transformer fails all too often in professional equipment, and while replacements for single voltage types (12+12V) are easy to find, this combination will be difficult. It is a potted transformer so a rewind is not possible.
Best course of action is to fit 2 separate transformers id there is room in the case Ed |
15th May 2021, 12:52 pm | #7 |
Tetrode
Join Date: Aug 2009
Location: Derbyshire, UK.
Posts: 50
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Re: Faulty power Transformator - replacement?
Ugh... thanks, Ed.
This doesn't look too promising, does it. |
15th May 2021, 4:07 pm | #8 | |
Guest
Posts: n/a
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Re: Faulty power Transformator - replacement?
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15th May 2021, 8:33 pm | #9 | |
Dekatron
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 7,580
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Re: Faulty power Transformator - replacement?
Quote:
All this means that the chances of finding a proper replacement are slight to impossible.
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17th May 2021, 12:40 pm | #10 |
Tetrode
Join Date: Aug 2009
Location: Derbyshire, UK.
Posts: 50
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Re: Faulty power Transformator - replacement?
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17th May 2021, 12:41 pm | #11 | ||
Tetrode
Join Date: Aug 2009
Location: Derbyshire, UK.
Posts: 50
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Re: Faulty power Transformator - replacement?
Quote:
It's a real shame, it's a lovely little unit. |
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17th May 2021, 5:40 pm | #12 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,903
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Re: Faulty power Transformator - replacement?
You could always put two transformers in an external box.
Ungainly, but OK if it's used as fixed equi[ment. David
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17th May 2021, 5:55 pm | #13 | |
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Re: Faulty power Transformator - replacement?
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28th May 2021, 7:27 pm | #14 |
Nonode
Join Date: Aug 2007
Location: Walsall Wood, Aldridge, Walsall, UK.
Posts: 2,874
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Re: Faulty power Transformator - replacement?
Hi!
Get a small 9V–0–9V transformer of about 5–10VA that will fit in the unit or on the PCB and use one of these kits for the high–voltage supply:– https://www.ebay.co.uk/itm/High-Volt....m46890.l49286 The Operation Manual for these is also a Service Manual with schematic diagrams and parts lists, so you can use the information in it to help you get the correct h.t. line voltage for the display! I note the RTW 1206D has a metal tubular stand – has this a hollow space you can use for a small 9V transformer and the PSU kit I suggest? Chris Williams
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It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed! Last edited by Chris55000; 28th May 2021 at 7:38 pm. |