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Old 8th May 2023, 10:09 pm   #1
high_vacuum_house
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Default Ekco U428 quick restoration

Good evening,
A quick restoration today as the weather was raining here all day.

I picked up this set last year for less than £5 at a BVWS event at the end of the day as there was little interest in it and I like valve sets with VHF.

The chassis construction is mostly on a PCB except the VHF tuner module which is still point to point wired.

The condition internally was good with a layer of dust which was soon vacuumed out and a fairly clean board emerged which showed that no components had been changed and even the valves looked the original Mullard fitted set.

Warming it up on the variac, it came on quite crackly on MW and sounded ok. The HT current was creeping up slowly over its maximum load and was then switched off before it got out of hand.

The 0.01uF UL84 grid decoupler was an old looking Metalmite and on removal showed considerable leakage on the megger and was replaced. There was also a Hunts Mouldseal from the tone control pot wiper to ground which was also replaced. All other capacitors in the set looked of good quality ceramic type and were left alone.

The valves in their sockets on the UY85 and UL84 seemed very loose and very carefully closing the gaps in the sockets made the valves feel a lot better held in place.

On powering up, the HT current rose to its correct level and was stable, The crackling had also ceased. MW and LW sounded very good. VHF was dead.

I found that touching the UCC85, would cause a lot of crackles. Cleaning the valve pins and closing up the contacts in its valve base sorted out the crackling on VHF and the band was also live with plenty of stations. The push button pre set stations were tuned into some stations which I didn't like so will leave it on the manual setting for now.

No other work was required on the chassis for now as everything works as it should and the radio sounded excellent when reassembled. VHF was surprisingly sensitive on its internal wire aerial inside the top of the cabinet. I have difficulty on receiving Radio 3 on some sets here but it came in loud and strong!! The UCC85 must be a particularly good one!! It has a decent sized Goodmans loudspeaker and a UL84 which you can really turn the volume up without any distortion!!

Cabinet work was just cleaning and polishing the wooden parts of the cabinet, cleaning the paint spots off of the dial glass and knobs and cleaning the dial light diffuser.

I decided to leave cleaning the speaker cloth for the moment as I could easily make it look a lot worse. Any ideas on how to clean it without it falling to bits ??

Christopher Capener
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Old 9th May 2023, 9:15 am   #2
vinrads
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Default Re: Ekco U428 quick restoration

Nice one Christopher, I like to find a carpet of dust inside it looks like it's not been touched for a while , as for the speaker cloth it's difficult you could make it worse if water is used I did it once and the paint on the board blead through , have never tried it but a dry cleaning product may work . Mick.
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Old 9th May 2023, 9:27 am   #3
paulsherwin
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Default Re: Ekco U428 quick restoration

Ekco used a lot of synthetic material for speaker board coverings and I think this is true of the U428. This generally survives cleaning well. I normally remove the speaker, then spray aerosol foaming carpet cleaner on each side, and gently agitate it with a soft paintbrush. I then wipe it off with a rag.

Of course, there's always a risk.
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Old 2nd Jul 2023, 4:31 pm   #4
Phil G4SPZ
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Default Re: Ekco U428 quick restoration

Nice job, Chris. Glad you got the VHF working okay, they can be tricky. Did you need to change the electrolytic cap in the discriminator circuit? I usually do that as a matter of course with sets of this age as it often reduces the distortion.

I’m just starting on a 1957 Ferranti with VHF that looks quite similar.
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Old 2nd Jul 2023, 4:48 pm   #5
stevehertz
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Default Re: Ekco U428 quick restoration

It's nice to do a restoration in a day, very satisfying.
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Old 2nd Jul 2023, 5:04 pm   #6
paulsherwin
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Default Re: Ekco U428 quick restoration

I think Christopher was lucky with this one. Like most early PCB valve sets, the PCB is very prone to going leaky causing hum problems, and the pads lift at the slightest contact with a soldering iron. It's also tricky getting the tuning scale lamps to work properly. U428s are often a lot of work, though they are nice usable radios once sorted out.
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Old 3rd Jul 2023, 4:51 pm   #7
Edward Huggins
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Default Re: Ekco U428 quick restoration

Quote:
Originally Posted by paulsherwin View Post
Ekco used a lot of synthetic material for speaker board coverings and I think this is true of the U428. This generally survives cleaning well. I normally remove the speaker, then spray aerosol foaming carpet cleaner on each side, and gently agitate it with a soft paintbrush. I then wipe it off with a rag.

Of course, there's always a risk.
I've made an old cloth look far better by using emulsion paint mixed to a similar colour and carefully applied (thinned) so as not to block the acoustic transperancy. Once dried off, it looked really good.
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