Repairing the CRT television I found

Bratz TV from 2006 ish

First, if you’re reading this in email, you probably aren’t seeing the pictures and video in this post. So visit https://sheddyian.wordpress.com to see this properly.

After letting the TV I found dry out for a few days, I took it apart to have a look. At the very least it needed a new mains cable as that had been cut off.

Nice set in its day

It came apart quite easily, though there was one security screw to thwart poorly prepared tinkerers. But I’m not poorly prepared, and had the right security but to fit it.

I desoldered the stub of mains cable and soldered in a spare one. I usually cut mains cables off things I throw away, with their moulded mains plugs they’re often handy. I have an old ottoman that my grandfather made, full of scraps of useful wire & cables.

I plugged the TV into an extension lead, shut the door and switched it on from another room. Just in case it went bang.

That’s… nice. But the colours look weird.

The TV powered up, and I could select the menu and the built-in DVD player, which gives a garish built-in picture. But the colours look strange, and the screen slowly wobbles gently from side to side.

Blue screen?

When set to a plain blue screen, the problem is clear. A large purple splodge, and strange colour on the bottom edge too.

On a CRT television, this is usually caused by the shadow mask in the tube getting magnetised. To defeat this, CRT TVs degauss themselves when you switch them on – the distinctive humm or thunk noise you used to hear. I switched this TV on and off a few times. I didn’t hear the noise, and testing with a compass showed no needle deflection. The degauss wasn’t working.

I looked at the circuitry in the TV connected to the degauss coil that runs around the tube. There’s not much to it. I noticed a 400 volt capacitor that was leaning over. Maybe it was damaged? The top was bulging. Aha! I unsoldered one of its two legs, and the capacitor fell out. The other leg had blown out of the capacitor at some time in the past.

I found some new ones on eBay at £3 for two including postage, so ordered those.

action shot

While I waited for the parts to arrive, I cleaned the TV a bit. The back of the case got a soak and a rinse in the shower, but the main unit had to be carefully cleaned by hand. As well as being grotty, it smelt if tobacco smoke.

I used sugar soap solution to clean off the dirt, and sprayed the inside liberally with febreeze air freshener which claims to have a deoderizing effect.

The Febreeze freshener was a bit sickly smelling, but after a few days that faded and the cigarette smell had also gone.

I imagine the original owner of this girl’s television set outgrew it and came to hate the characters, so they stuck parcel tape over them. But the Bratz are still there. Watching.
Exploded capacitor on the left, new one on the right. Yes they are the same ratings!

New capacitor arrived, so I fitted that and tried the TV out. The screen remained splotchy.

Reading online, the tool I needed was a degauss coil. I don’t have one of those. They’re not cheap to buy, and how often am I going to use it in the future? So what else could I use?

I tried waving a strong magnet near the screen, which made pleasing blobs appear and disappear on the screen, but didn’t remove the original splotchy colours.

I don’t have a degaussing coil, but I do have a tape head demagnetiser tool. Tape heads get magnetised over time when playing cassettes, which causes a muffled playback sound. Demagnetising will fix that.

Maybe I could use that tool, and wave it around near the screen?

Lava lamp effect – watch the video for degaussing action

Waving the demagnetiser around caused instant splotches to appear and disappear, bit also after repeated tries, the original splotchy was getting smaller.

I continued this until the screen colour was very nearly perfect.

I adjusted the settings, reassembled the case and played a dvd.

It works! The built in DVD player is a little noisy, but I’m unlikely to use it. I’m not intending to watch TV on it, and can’t anyway without a digibox, as the TV only has an analogue TV tuner.

But what I do want it for is this

ZX81, with 1K of memory

My first computer, from 1982. A Sinclair ZX81. It plugs into a TV, has no sound, is black and white output, and has a strange “keyboard”. I learnt to program on this!

But the repairs if that are for another blog post…

Wombling

I’ve got a new telly

I found it by the roadside, and it’s currently in the porch drying out.

It seems likely it’s dead, as the mains lead has been cut off, but you never know. I’ll give it a few more days to dry out then I’ll wire a new mains lead to it and see what happens.

The “Why?” is that I have my original computer and I’m keen to set it up again.

A Sinclair Zx81, but not my one

I got my ZX81 in 1982, it has 1K of memory, plugs into a TV and stores it’s programs on cassette tape.

Although they can be plugged into an LCD TV, they look and behave best on an old CRT television, hence my excitement at finding this dumped one.

Updates soon, maybe even live video of it going bang when I switch it on.

Restoring Sight To Your Robot

My robot vacuum cleaner couldn’t see very well. It would very frequently bump into things, often quite forcefully.

I can see perfectly

In fact, I’d assumed this was how it was, as I didn’t remember it not bumping into things. But it shouldn’t.

The robot has a number of ways to detect whats going on. There’s sensors underneath, so it won’t drive off the landing and down the stairs. There’s bump sensors along the front so that when it does crash into things, it knows and backs off. And there are infra red transmitters and sensors around the front.

These allow the robot to “see” the infra red reflecting off objects, so it can slow down and avoid crashing into things.

Except, in my case, it was forever crashing into things, often with some force. Setting the robot to clean in another room would result in bangs and crashes from the room as it cleaned. It still cleaned well, but noisily and by pushing lighter pieces of furniture around!

Why did it crash into things? The front plastic that the infra red shines through was badly scratched, even had paint marks on it from constant scraping and bumping. These marks effectively made it blind.

A year or so ago, I bought a cheap Dremel style tool from Aldi in a sale for about £10. A bargain! I’d not even opened it until recently.

Not a Dremel

For the price, it’s surprisingly good, and battery operated too.

So, with a polishing wheel fitted to the not-Dremel, I cleaned and buffed the plastic front of the robot. Initially I did this dry, then I applied some Brasso metal polish with a rag, polished it by hand and finished it off with the I-Cant-Believe-Its-Not-Dremel tool.

The result was a plastic that still had scratches, but much less severe, and the paint scrapes had gone.

And now the robot cleans near silently. When it’s heading for a wall or piece of furniture, it gracefully slows down then turns away. Bangs and crashes, previously a constant feature of cleaning, are now very rare.

Newer and much more expensive robot cleaners use cameras, radar and lasers to know where they are and to plan a route and avoid things. My robot doesn’t, it just uses infra red and a bump sensor. But the improvement from polishing the plastic now gives the impression it’s a much more advanced robot!

Speakers Corner

In the corner of my kitchen, I have a cheap DAB radio.

It was originally my Dad’s, it cost almost nothing as it was bought from Tesco with clubcard points.

It sounds… alright. Ish.

But at louder volumes, it shows it’s cheapness, sounding very thin. Although it’s stereo, it doesn’t sound very stereo, theres little separation.

(Note that a lot of commercial DAB stations don’t even broadcast in stereo, and are at shockingly low bit rates. Here, I’m listening to BBC 6 Music or radio 3, which are stereo and at ~tolerable~ bit rates)

Could I do something to improve the sound? Well, I can’t change the bit rate the stations are broadcast at, and I could just buy a better quality radio, but let’s tinker a bit.

donor

I’ve some computer speakers that have lost their non-standard power supply, so I looked at those. By happy chance, the driver units in these are the same size as in my radio!

New speakers in, old speakers out

I unsoldered the existing radio speakers, and put the donor speakers in. They fit!

At this point, I wasn’t sure there would be an improvement, as the existing speakers looked better. Larger magnets, chunkier design. I switched it on, and it worked, and sounded ok.

But how to tell if it’s better?

I put one of the old speakers back in, and switched to radio 3. I then did an old new old new old new comparison, and was a little disappointed that the new speakers didn’t sound stunningly better, they were nonetheless better than the old. There was a difference. The sound was richer, less thin.

But I knew which speaker was which, and I wanted my upgrade to work, so there might be an unconscious bias here.

So I did the same test with Jeanette listening, who didn’t know which speaker was which.

Jeanette also thought the new speakers sounded better, so I fixed them both in permanently.

What about the stereo separation? The inside of the radio is hollow, nothing isolating the speakers from each other.

cardboard and glue

I cut some pieces of stuff corrugated card and made two dividers, so that when the case was reassembled, the speakers would be in their own isolated chambers.

I also added a lining of speaker dampening material that I had lying around. Although it could have been cooker hood charcoal filter. Anyway, it seemed to give the sound an extra bit of depth, though I didn’t blind test this bit so it may have been wishful thinking here.

All done

It’s all back together now, and working well in the kitchen. It does sound better, and even with the speakers so close together, the stereo is much more noticeable now.

Now, what to do with the old speakers I took out? I wouldn’t ever throw them away!

Replacement rubber seal for Eufy Robovac 11S

A few weeks ago, I washed the dustbin from my robot vacuum cleaner, and put it outside to dry.

when I came to bring it back in, I saw that the rubber seal was missing.

The seal sits under the door that gives you access to the two filters. The rubber seal was loose. Now it was gone. If I’d dropped it, I haven’t yet found it several weeks later. It either blew away or a bird grabbed it thinking it was a worm.

I searched online for a replacement seal, but didn’t find one. I found a 2nd hand dustbox at an inflated price, and of course filters and brushes, but not the seal. So I’d have to improvise.

I measured the perimeter of the groove that it sits in (115mm) and found a replacement drive belt online, intended for a cassette recorder. I figured that a 2.5mm square section drive belt, of appropriate length, would make a good substitute for the original seal.

It’s just turned up, and I excitedly fitted it.

A belt and a dust bin. Will it fit?
Yes it fits!

It was a little fiddly getting the belt to snap in without twists, but after a few minutes I got it right, and the door closes firmly against the seal.

Good as new, with filters refitted

So if you’ve lost the rubber seal on your robot vacuum cleaner, measure the perimeter of the hole and buy a square section drive belt for tape decks on eBay.

In the case of the Eufy Robovac 11C, it’s a 2.5mm x 115mm belt that works for me.

It arrived just in time, my house was getting dirty with no robot to clean it.

Small disaster

I washed the dirt bin on my robot vacuum cleaner the other day. I empty it every few times I use it (or when it’s full), but I also like to wash it out every few months.

After washing it, I put it in the shed roof to dry. It’s a metal roof, corrugated, so things drip nicely, the breeze and warmth soon get things dry.

When I came to bring it back j doors, I noticed the rubber seal was missing. It fits under the door where you get access to the filters.

I’d al.oat lost it before, as it had dropped out when washing last year. This time I’d noticed it was loose but was careful not to drop it. Anyway, it’s quite large.

But it had gone now. I looked everywhere – on the roof, the gutter, the ground. Nope. I suspect it either blew away or a bird grabbed it, mistaking it for a worm.

I measured the gap that the seal fits into, and found a 2mm square section rubber belt on eBay that would fit in a cassette recorder drive mechanism. I think this will work well as a replacement.

Will post a picture when it arrives, and hope it works, as my house is getting dirty!

Reusing old batteries

(I couldn’t think of a pun title)

A few years ago, I got myself a battery charger. I already have several chargers, for Nicads and ni-mh batteries. But this one claimed to recharge ordinary Alkaline batteries as well! You know, the ones that always have “do not recharge” printed on them.

Long story short – it does sort of work. If the battery is dead, it won’t recharge. If it’s only partially used, it will refresh it.

Some will leak after they’ve been recharged, Duracell’s seem to be the worst at this, I no longer attempt to recharge those.

I sometimes grab a handful of old batteries from the recycle points in supermarkets. I test them with a meter when I get home to select batteries that are likely to work in the charger.

And it’s this testing that revealed something that surprised me – people are throwing away batteries with lots of life left in them, occasionally it seems they’re entirely unused! These don’t even need putting in the charger!

As an experiment for this blog, I grabbed 4 AA batteries from the overflowing battery recycle bin.

Battery 1 gave a twitch on the meter dial then showed nothing. It’s dead.

Battery 2 seems to have about 1/3 rd capacity

Battery 3 is dead, nothing at all

Battery 4 shows as full in my meter, or it’s unused!

I put all 4 in the charger, and it started to charge 2 if them. It wouldn’t charge 1 & 3, which were the twitch battery and the entirely dead batteries. This is what id expect.

Red light means charging, no light means no charge. Light goes green when it’s done (about 3 hours)

So I’ve gained 2 free batteries, one of which was close to new. This backs up past experience, I’ll usually find one or two hat are as good as new, a good few that are only part used, and a few that are entirely dead.

What a waste! Throwing out perfectly good batteries! Get a battery meter and test your batteries! Even if you don’t go to the trouble of recharging like I’m doing, you can make sure you only recycle batteries that are actually dead.

Finally, I should note that you should never put alkaline or other non rechargable batteries in an ordinary charger. At best that’ll leak, they could Exide or catch fire!

Even this magic Alkaline charger is no longer available, so maybe it’s too risky or too many batteries leak afterwards. Ive certainly had mixed results, but it’s a fun way to save on waste and to get batteries for free for tinkering projects.

An old mystery box

I dug out my board game of Cluedo the other day, and we played a game, which was fun. I’ve had this since I was a child, and not played it since then.

Yes, the caption on this blog post is misleading, but it is old and it’s a box of a mystery game. Plus there was a fun unexpected surprise inside. Read on…

I always liked the game, partly because it always felt old. The style and artwork feels 1930s like, perhaps reflecting Agatha Christie, even though I wouldn’t have known that as a kid.

ugh

So it irks me seeing the modern board game design and box. It seems to lose all that character that I like. I must be getting old, I don’t like modern things.

I wondered how old my game was, and found some different dates scattered around.

The box states ©1965 and 1972. The box does look old and basic, the typeface and layout in particular.

The instructions say ©1975, suggesting they’re the newest part of the game, because…

…on the board is ©1949 ! Had the board not changed design between 1949 and 1975? Maybe not. I think this is why I liked it as a kid (and still do), it felt like you were wandering around an old house as you played the game.

I was pleased that all the pieces were still in the box, with the exception of the dice, so we used a dice website on a phone to roll out turns. See, I do like new stuff too.

The surprise was in the box under the board. Mindful that there were a finite number of notelets on which to cross off eliminated suspects, rooms and weapons as you play the game, we’d put some scrap paper in and written on those as kids.

My dad worked as an electrical wholesale rep, and often brought home old promotional leaflets and brochures that were out of date, as they were often one sided and so we children could write and draw on the reverse.

And in the box were three retail price lists for Chloride Exide Dry Batteries, torches lamps and bulbs, dated 1st October 1979.

This is fascinating. There are so many battery types there that aren’t in common usage now (PP1, PP6, flag, HP16). Many were those larger square/rectangular 6 or 9 volt batteries that sat in the back of a transistor radio and were surprisingly heavy. Modern equipment will typically use multiples of AAs to do the same thing, and with greater capacity as they’re alkaline. There’s another thing – this price list is before alkaline batteries were common, so these are all zinc chloride or zinc carbon. The sort of battery that leaks easily when it’s flat, and doesn’t last that long either.

And the prices! You might think, oh 12p for an HP7 (AA) battery, that’s cheap! But it’s not.

12p in 1979 is 61p in 2019, according to the Bank of England inflation calculator. 61p for one zinc carbon battery. Today, you can get a card of at least six, often ten similar batteries for £1. You can often get a card of 4 alkaline batteries for around £1, that’s 24p each for batteries that last a lot longer and are less prone to leak.

So, I do mostly like modern things, they’re generally better. But I like looking back at old stuff (and I may well post more about the Chloride Exide price sheet as I want to look up all those mysterious battery sizes). But I don’t like the new Cluedo.

You don’t get these any more!

The Mystery of the Missing Grape

One evening, a few months ago, I was watching TV and eating grapes. A nice healthy snack.

I dropped one. I looked for it, and couldn’t find it. On the floor? No. On the sofa? No. Under the sofa. That’s where it’ll have rolled. No.

I couldn’t find it. Next day, I looked again with the magic of daylight. Still couldn’t find it. I was anxious that is tread it into my carpet, but as I’d already searched and failed to find it.. well that risk was minimised at least.

I sent the robot vacuum cleaner to look for it. A grape is probably too large for it to sweep up, but I thought perhaps it’d dislodge it or roll it out of hiding. But it didn’t. No grape.

Over the next 2 months I occasionally wonders where the grape had gone to. Mice seemed the most logical, although I’d never seen any signs of mice in the house.

Then yesterday, I was cleaning the coffee table and I removed the clutter from its lower shelf to clean it.

And there on the lower shelf

was a plump home made raisin!

It’s tempting to taste it, but that didn’t seem too hygienic. I’m still pleased to have solved the mystery though.

And whilst I have an occasional frog in the shed, I don’t have mice in the house

Kitchen Sockets

I’m going to try to blog a bit more often about smaller things I’m doing. Quite often, I make or repair or modify something, but don’t blog about it because I forgot to take a before picture. So I don’t write about it. But I’ve decided not to let that stop me writing at least something, so perhaps there’ll be a bit more here.

That said, today I have a before and after pic. The sockets in the kitchen were hanging off the wall, as they’d been poorly installed. They were black ones, which could look nice, but easily show fingerprints.

wonky and loose

They don’t fit tightly against the wall as the box inside the wall has extra lugs that get in the way.

I hammered the lugs flat into the box, and put new MK sockets in their place.

Much nicer – and almost straight

The old sockets were missing an earth flyleaf to the metal box, so I put one of those on, and tidied up the wires a little bit.

The kettle, coffee maker and toaster go here

Power back in, all working and I made a cup of tea which tastes nicer now the socket is a good one