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Old 16th Dec 2018, 1:41 pm   #1
a_strong
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Default Regentone W5A Eliminator - Information required...

Can anyone please tell me what is intended to fit in the holes marked H, M, L on the attached picture? Initially I thought that they may be 3.2mm wander plugs or screwed selectors such as those for selecting the mains and accumulator voltage but neither of those fit.

I would also like to know the capacity and working voltage of the three capacitors that can be seen at the bottom right hand side of the attached image. Any markings are indistinguishable.

Thanks for reading!

Regards - Alan - G3WXI
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Old 16th Dec 2018, 2:00 pm   #2
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Default Re: Regentone W5A Eliminator - Information required...

Caps need to be at least 8uF 250 VDC,H= HT M=Screen grids feed L is the lowest voltage. The LT is to charge an accumulator normally 2volts. You flick switch to LT when not using the set.

PS Will be surprised if the caps are not marked with voltage and rating under the muck.
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Old 16th Dec 2018, 2:26 pm   #3
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Default Re: Regentone W5A Eliminator - Information required...

I have the W1F version of this, which is physically very similar, but does not supply LT current.

Circuit here:-

https://www.service-data.com/section...ery-eliminator

H, M and L stand for High, Medium and Low voltage. SG is Screen grid.

The biggest problem with these eliminators is poor connections to the dropper resistors which the H, M and L sockets connect to on the rear of the Bakelite panel.

Sockets take 1/8" dia plugs of the split pin type.
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Old 17th Dec 2018, 12:48 pm   #4
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Default Re: Regentone W5A Eliminator - Information required...

Hi O.M. - I have the excellent article published here http://www.richardsradios.co.uk/regentone.html
which gave me the information that I used in my original posting.

You are almost certainly right when you say "you will be surprised if the caps are not marked with voltage and rating under the muck." but I am reluctant to start any srious dismantling without the full circuit diagram for this particular item. What threw me a bit is that on of the capacitors appears to be marked "1.0mfd" voltage not readable and another appears to have a red spot on one end and is marked "35VDC wkg" which I presume will be the LT smoothing.
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Old 17th Dec 2018, 1:12 pm   #5
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Default Re: Regentone W5A Eliminator - Information required...

Hi Graham - thanks for your reply, my reply to HamishBoxer also addresses some of your comments. When I spotted the pre-set resistors beneath the congealed mass of wiring below the Bakelite panel I mentally flagged them as being a potential source of trouble and plan to replace them with more modern presets once I have ascertained their resistance values.
You say: "Sockets take 1/8" dia plugs of the split pin type.", I have not tried a wander plug yet but the shank of a 1/8" drill will not enter any of the sockets, I appreciate that a wander plug is more compressable than a 1/8" drill!
Can you tell me, are the sockets marked + & - are HT or LT connections? You will appreciate that I have not yet started to check between the various sockets for contunuity.

Regards - Alan S.
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Old 17th Dec 2018, 1:23 pm   #6
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Default Re: Regentone W5A Eliminator - Information required...

The -ve and +ve sockets both relate to the HT supply. There's a resistor connected between -ve and +ve with taps at L, M and H, So +ve is at a higher voltage than H.

In addition to the two 8uF capacitors my unit has a 0.5uF cap which appears to be a decoupler for the SG supply.

I think your chances of finding a circuit are slim, so you're going to have to reverse engineer it, which is what I did with mine.

I'll endeavour to check the socket sizes this afternoon.
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Old 18th Dec 2018, 2:04 am   #7
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Default Re: Regentone W5A Eliminator - Information required...

Hi Graham - I could not decide if the H, M, L, holes were connection points or if they were voltage selectors for the H, M, L voltage appearing at the sockets marked -ve & +ve. Then there is the matter of how the SG or Det ranges are selected.
I think my plan of action should be to replace the capacitors, then check around with my resistance meter and if nothing untoward is found, connect the W5A to the mains via a series 15W pygmy bulb current-limiter then check with a multimeter what, if anything appears at the various sockets.

I did try a 2mm banana plug in the sockets but it was a very sloppy fit, as expected. I came across a piece of wooden dowel about 2.8 - 2.9mm dia which is a sniug fit in the sockets so please do not go to the trouble of checking the sockets on your eliminator because it is something I should have done for myself sooner.

Regards - Alan S
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Old 18th Dec 2018, 10:31 am   #8
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Default Re: Regentone W5A Eliminator - Information required...

If your eliminator is wired like mine, then the tapped resistor across the HT supply is a potential divider. This means that voltage measured off load will be different to that measured on load, as the load will be in parallel with the "lower" sections of the resistor.

The other tapped resistor is wired in series with the SG supply, so the measured off load voltage will be the same on each tap. It's effectively a screen grid dropper resistor external to the radio.
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Old 13th Jan 2019, 2:18 pm   #9
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Default Re: Regentone W5A Eliminator - Information required...

Alan.

If you get this going I'd be interested to know what off load voltage you measure between the + and - terminals with the High/Low in each position.

The mains transformer on mine has an open circuit secondary. I'd like to able to work out how many turns to use on each side of the tap when rewinding it.

Thanks.
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Old 14th Jan 2019, 9:57 am   #10
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Default Re: Regentone W5A Eliminator - Information required...

Good Morning Graham - I suspect the rectifier(s) in my W5A may be shot, although it may be O.K. and my DVM just too sensitive or not apply sufficient voltage for a meaningful test because both forward and reverse resistances read more or less the same. However, resistance tests on the transformer primary windings appear to be normal.

The W5 has been sitting on the kitchen radiator for the past 5 weeks drying out before I dare do any insulation tests on it. If they check out O.K the next test will be mains via a Variac with a 15W pygmy light-bulb current limiter in series.

It is egg-on-face time (again) with regard to the type of plug to fit the front panel sockets. I eventually found a couple of unused vintage wander plugs and they fit just a treat!

Back to the point of your message, I will certainly do as you ask. Can you just confirm that the High/Low Selector to which you refer is the HT range selector screw on the control panel.

Presumably you require off load voltages?

If it is of any use, the resistance across the mains lead is 167Ω on the 200-220V range and 188Ω on the 230-250V range.

Re: The transformer, Ed Dinning did a superb job reverse engineering a transformer for my KW Monitor 'scope.

Regards - Alan S.
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Old 14th Jan 2019, 12:15 pm   #11
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Default Re: Regentone W5A Eliminator - Information required...

Thanks Alan.

Yes it is the HT range selector screw I'm referring to. The resistance values you quote are very useful, as given the wire gauge I could just calculate the length of wire needed either side of the tap. Measuring it might be more difficult though.

Ed has done great work for me in the past, but I am confident I can rewind this transformer myself as it has split bobbins and the laminations are held in a 'U' shaped yoke. In fact I've already dismantled it.
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Old 15th Jan 2019, 2:10 am   #12
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Default Re: Regentone W5A Eliminator - Information required...

Good Morning Graham. I am getting to the stage where I would be prepared to take a chance and put some AC through the primary. However, our son who we have not seen for a couple of years is about to visit from Australia so my playtime will be somewhat curtailed but as soon as I can, I will measure the AC voltages of the HT and LT windings with 24VAC on the primary with the mains voltage selector in the 230-250V position. That should give you some idea of the turns ratio on each of the windings.

The following may be of interest:

Quote: The transformer has one winding giving 8 volts off load and another tapped winding giving 150 volts with a tapping at 140 volts selected by the insulated screw on the front panel.

Alan
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Old 15th Jan 2019, 2:32 pm   #13
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Default Re: Regentone W5A Eliminator - Information required...

Thanks Alan.

There's plenty of information for me to go on now. I might try a trial rewind.

Enjoy your son's visit.
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Old 28th Jan 2019, 10:12 pm   #14
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Default Re: Regentone W5A Eliminator - Information required...

Hi Graham - I will be interested to hear the outcome of your endeavors in due course. Apologies for the deafening silence, which was due to email problems at my end. Google bullying an O.A.P. (Very!).
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