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Ancient Geek 27th Sep 2017 4:29 pm

First restoration: Regentone A155
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So, my first restoration is complete, at least for now. I picked this set up from a local auction house. I chose it because it was redolent of my early years: an early VHF woody with a magic eye tuner, although it's not the one I remember us having as a small boy, which I believe was a KB NR30.

This set was filthy with tobacco tar and dust, some scratches and dents to the cabinet, but otherwise complete. The first step was removing the chassis, followed by a lot of cleaning. I discovered that WD40 is very good for cleaning tobacco tar from cellulose lacquered woodwork, but you need to be a little careful, as it does temporarily soften the lacquer a bit.

Step two was extensive reading of this forum to learn as much as I could before starting, followed by the construction of a lamp limiter. I identified 5 or 6 TCC waxies that definitely needed replacing, plus a few other caps that probably did.

I replaced the waxies, then reformed the smoothing caps as best I could with my max. 48V bench supply and then applied power via the limiter. The set came to life on LW, with no bangs or smoke. Emboldened, I switched to full power. Again no bangs. Pots very scratchy, lots of rustling, and very sibilant FM. Measurements showed all the secondary voltages to be about 10% high, despite the correct primary tap being selected. I elected to fit a 100R 10W wirewound in series with the primary, which sorted that out, and the panel lamp was replaced.

All contacts and wipers were cleaned with Deoxit, which made a big difference. Extensive reading of the forum suggested that the ratio detector DC load capacitor would likely be duff ( a Plessey red yellow and black one), so it was replaced. This did not improve the FM, and subsequent checking showed the original to be OK.

All capacitor replacements were carried out using the 'small coil of wire splice' method, which worked well. The EM80 was physically broken, probably when the AM dial cord was interfered with (more on that later), so I ordered a couple of 6E1P replacements from an Ebay seller in Moscow. When they arrived, I found that they worked well, but would not physically fit in the cutout in the rear dial plate, being too tall. I made an enquiry to Langrex, who assured me that theirs would fit, so I ordered one. Guess what? It was almost identical to the Russian ones. Having already thrown quite a bit of money at the set, I decided to bite the bullet and enlarge the cutout.

Having read that FM sibilance may be cused by alignment issues, I decided to have a go at FM IF and discriminator alignment, following the steps outlined on the trader sheet. I have an old HP 8116A function generator and a Rigol 'scope. I used an XR2207-based triangle wave generator as the modulation source for the 8116, via a homebrew opamp circuit to tweak the levels and to ensure it was centred on 10.7 MHz (the 8116 is out of cal).

I got nowhere with this, and ended up getting further and further out of alignment. I found a Youtube video ( showing a simpler method, which I found easy and, seemingly, accurate. The FM is now reasonable and less sibilant, although not impressive by today's standards.

I did encounter a problem with intermittent rustling, with was independent of the volume setting. Replacing the EL84 cathode bypass capacitor seems to have cured this.

The AM tuning was slipping, and I discovered that it was incorrectly strung, with the spring in the tuning capacitor pulley and the cord too short for correct stringing. I acquired some new cord and restrung it according to the diagram on the trader sheet with no problem.

Regarding the cabinet, I repainted the metal speaker grille and the gold rings on the knobs. Restoration was rounded off by replacing the twin core mains cable with a three core one and earthing the chassis. I decided not to attempt any further cabinet restoration, but live with the fact tht it's have a few knowck and scratches. I'm pleased with the end result -- AM reception in particular is very good.

As my other main hobby is photography, I thought I'd try and round this post off with a shot of the set with a period atmosphere, hope you like it. Thanks to all of you who offered helpful advice to a beginner to the world of glass bottles. Not a difficult restoration by the standards of this forum, but a satisfying one for me as a beginner.

Boater Sam 27th Sep 2017 5:23 pm

Re: First restoration: Regentone A155
A lovely success story. Just proves that a bit of care and consulting others can produce excellent results. A credit to you.
And that is a fabulous photograph, clarity, content, composition. Puts me to shame. It would make a good avatar for you on the forum.
The cabinet looks much better than your write-up led me to believe, its beautiful.
The sibilance on FM may be the balance on the ratio detector legs, its not unknown for the diodes in the detector valve pair to be way out of balance, try a fresh valve and re-adjusting. Or even replace with a pair of semiconductor diodes as a test or a solution.

Ancient Geek 27th Sep 2017 5:59 pm

Re: First restoration: Regentone A155
Thanks Sam :) , and apologies for the proliferation of typos which I didn't spot before posting :( .

Tractionist 27th Sep 2017 8:26 pm

Re: First restoration: Regentone A155
Very handsome looking set - bravo ..... I believe you deserve that drink sir!

Andrewausfa 27th Sep 2017 8:43 pm

Re: First restoration: Regentone A155
Excellent story and excellent photograph, well done.

Next mission; build a higher voltage reformer :)


Ancient Geek 28th Sep 2017 8:22 am

Re: First restoration: Regentone A155
Thanks, chaps. Andrew, I have an idea in mind...

Nickthedentist 28th Sep 2017 9:54 am

Re: First restoration: Regentone A155
Great write-up and a nice result.

Your evocative photography is wonderful too. The only thing that's missing is an ash-tray or a pipe (not that I've ever smokes, mind you).

Yes, do build a re-former. I built the one detailed on Paul Stenning's restoration pages. It's very useful and makes me more confident about applying power, as well as telling me whether a big electrolytic is beyond redemption and needs to replaced:

I wonder whether the FM is working as it should. I have to say that I've been pleasantly surprised by the sensitivity, selectivity and fidelity of some early VHF sets, e.g. Bush VHF61/2 and 64 and Ekco A277, but we are fortunate to have a strong signal here in Oxford.


music-centre 28th Sep 2017 6:19 pm

Re: First restoration: Regentone A155
That looks great, the case looks in excellent condition. Possibly the FM is not quite right though by your description, I used one of these as a kitchen radio for about 5 years until fairly recently (stuck on top of the fridge :-]) and I found the FM to be really good, sensitive and would go to a good volume.

Sorry that doesn't help you find what (if anything) is up with it!

Ancient Geek 28th Sep 2017 10:00 pm

Re: First restoration: Regentone A155
To be fair, FM reception round here is not very good, so I'll try a better aerial before digging any further.

Nick, I did want to include a pipe, but don't know anyone who has one. I'm slowly increasing my stock of still life props, so maybe I'll revisit this one day.

Phil G4SPZ 4th Oct 2017 8:13 am

Re: First restoration: Regentone A155
That looks lovely. And the radio looks nice, too! Well done.

mjddewet 5th Oct 2017 1:34 pm

Re: First restoration: Regentone A155
Your taste in liquid refreshment is also to be recommended..

And the radio does the photo justice...

Ancient Geek 5th Oct 2017 3:16 pm

Re: First restoration: Regentone A155
Thanks for the kind comments. Still working on the cap reformer...

PaulR 11th Oct 2017 1:03 pm

Re: First restoration: Regentone A155
That looks really good, almost like an advertisement photo from when the set was new might have been.

Regentone has rather a down market reputation these days but I restored an AM only set from the late 1940s recently and was surprised by the build quality. Unfortunately mine had been kept in a semi open building at a local antiques centre and the original finish was beyond saving.

What is next??

Ancient Geek 12th Oct 2017 12:14 pm

Re: First restoration: Regentone A155

What is next??
There are a couple of auction lots I have my eye on. :)

Tim 31st Dec 2017 11:07 pm

Re: First restoration: Regentone A155
As a first time that's excellent. I have a feeling that this might take over form the photography!

BigClick 23rd Jan 2018 8:53 pm

Re: First restoration: Regentone A155
That is beautiful and puts my a155 to shame

great picture

McMurdo 23rd Jan 2018 10:07 pm

Re: First restoration: Regentone A155
I was going to compliment you on the photograph before I read your last bit about being a photography buff, now I know why it's such a pleasing composition.

That radio looks like new, so here's to the next one. We like nice pictures of pretty radios!

My very first valve radio restoration was a Regentone too, so I can't hear the name without coming over all warm and nostalgic.

PS your resto' also puts mine to shame.

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