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Sunday 16 June 2019

Beko DW686 dishwasher repair

It's been busy lately. If you follow my YouTube channel, you'll be waiting for an update on the Sony 9-306. It may be a little while, as other things have got in the way.

Anyway, came downstairs in the morning, ready for a cup of coffee and a bit of breakfast before going to work, and I step in a pool of water... Ugh.

The dishwasher (aka "the magic chipboard") has leaked everywhere, and not washed the plates either!

I got home and needed to tackle the repair. I have an irrational hatred of dishwashers.

I reset it and it pumped the remaining water out. I tried to run a cycle, but it wasn't having it...




I dragged the thing out and removed the front lower panel. It's full of water, and there's bound to be a float switch in there ..











.. (probably behind that central polystyrene float) that stops it from running when the sump is flooded.
















I tipped the machine forward slightly to empty the sump, but it still wasn't running correctly.

I thought perhaps the level switch wasn't working, so it didn't know how much water it had let in (hence the flooding) I removed the side panel and started looking for a pressure type level switch...














... there isn't one...
















...however there's this. It's a small flowmeter in the inlet pipe.

I did a spot of googling, and found some information about a test mode.














Hold these two buttons down and switch on.











After lighting up all the display segments, this is displayed... hit the play/pause (!) button to start the test running....











After going through the motions, Er2 is displayed. Er2 is the error code for "no water", despite the fact that there's definitely water going in, as I can see it gurgling through the pipes ...









OK, suspicion turns to the flowmeter. I decided to remove it and inspect.

Undo the two pipe clips...












Slide the pipes off (easiest to do the bottom one first). Expect a bit of water to leak out...


















And remove the electrical connector....














With the flowmeter removed, I blew through it. I can hear the impeller turning. I can test to see if there's an output by measuring continuity across the device. Those two oval holes provide access, rather than trying to probe the connector.

It seems to be open circuit.

A new one is about £11 eBay. I decided to see if this one could be fixed...



I removed the small green PCB, and it contains a magnetic reed switch. This is simply a small switch in a glass bead which closes when there's a magnet near it. I stick a magnet near it, and it's still open circuit ...







A quick trip to NP Harding provides a slack handful of suitable looking reeds...











One is duly fitted, and tested... it still reads open circuit with or without magnet.... hang on? What I hadn't done, was check the meter was working correctly! It wasn't. It appears one of the probes has gone open circuit! Aggggggghhhh!

Replacement probes fitted, and the flowmeter tests perfectly. I test the reed I've removed ... it tests perfectly .... damn , I've wasted a lot of time ... I'm so cross with myself!

Right, back to the kitchen and re-install the flowmeter.

Run the test again. Same results Er2. No Water. I measure the voltage on one pin of the flowmeter, and there's a solid 12 volts there.... on the other side there's a varying voltage (because of the pulse train) ... OK , that's working....

There's a fault finding flowchart in the service manual (download it here). It says the next step is to check/replace the controller board... It's mounted in the door....

Undo the screws either side of the latch, and the two holding the decor panel on (if fitted, mine's a built in thing) I chose to remove the decor panel completely, as it's front-heavy with it attached)

Another two screws down each side, and you can pop out the plastic top, and gain access to the electronics.

Note the new meter probes! The plug you see removed here has the two purple wires from the flowmeter. Sure enough one is open circuit! I bet myself a nice cup of tea that it's where the wiring goes round the hinge of the door.....

A wire is temporarily fitted to each end...




























and the test mode run again...

and it passes :)










Now to route a new wire in. I thought I may use the old wire to pull through the new one... no chance as it's completely broken... Just long enough to indicate the break is indeed in the hinge... :(













... So the door has to completely come apart. Disconnect both the springs from the door and use something to support it whilst doing this. I found it easiest to lower the spring tension as much as possible with the two plastic adjusters that are just down from the top of the door aperture behind the seal. You'll need to remove the other side panel as well if you haven't already done so.

A word of warning here ... this panel is sharp. Damn sharp. Wear some thick gardening gloves or similar.


And there's the wiring....












The new wire is threaded through (better to start at the top and work down) , soldered at both ends and given a coat of liquid insulation tape (because I've not got any heatshrink at the moment!)









The machine is reassembled, and test mode gets to P3, which has passed the water inlet issue :)











Eventually it's all back together and washing the plates again... for now. What about those other dozen-or-so wires going via the hinge? I'll worry about those another day!

Another saved from land fill (for now!)

... and I won my bet, and have a nice cup of tea ;)

Monday 13 May 2019

Ekco U353 - a quick restoration.

Ages ago Steve was good enough to bring up Sam's Queen Anne for some repairs. Also in the boot of Steve's car was a broken Ekco U353. Now, I have one of these, (see here!) which I repaired ages ago. It's a basket case, and remains unused as it's knobs are missing.  The knobs are an essential electrical safety item, as the chassis is connected directly to the neutral of our mains supply (common practice back then).

Anyway here's Steve's...


Much better nick than mine, although there's a crack to the right hand side of the cabinet... 











... and the back's a little distressed where the heat from the rectifier and output valve has made the back brittle, and damage has occurred. Some of the brackets are in poor shape too.










Removal of the chassis is straight forward, off with the knobs (there are two small grub screws to undo), and removal of four screws on the underside of the case.










It all looks very clean and unmolested.












Amongst the dust in the bottom of the cabinet, a tell-tale blob of wax shows something's been getting hot...











... and sure enough ...












... C61 has had a right sweat on! As usual, these waxy caps will all be shot, if not now, in the very near future, and will all be evicted. C61 is the mains input filter cap, so it's replaced with a brand new X2 class safety capacitor. It's 0.01uF.







Now in my example, the output valve had been cooked as the cathode bypass capacitor had failed short, so this is also replaced. In fact there's very few capacitors in the whole receiver, so every electrolytic, paper/wax and hunts capacitor is replaced, except the main multi-section smoothing capacitor.








The cathode bypass capacitor is C55. C50, C49, C46, C1 and C20 are all replaced. C1 is a horrible black hunts thing.






After the caps are replaced, it's time for action. The receiver is connected to the variac, and the voltage slowly increased for about an hour, monitoring the HT voltage, and periodically checking the temperature of the main multi-section smoothing capacitor to see if it's getting warm. It wasn't.

After a quick tune about, stations are coming in, and the FM seems to working too. The receiver is aligned in accordance with the service sheet, and it's performing well, except the exclamation mark magic-eye isn't illuminated :(

R14 (68K) has risen in value to many megohms, and crumbles as I remove it! After it's replaced the exclamation mark works as it should.









The guilty parties!












... and the elusive knobs ...












A piece of car body re-enforcing mesh is cut out to cover the damaged areas of the back...











... and it's filled, drilled and painted. Not the tidiest job in the world, but it'll render the set electrically safe, and allow the required ventilation.









The set's plug is fitted with a more suitable 3A fuse (there's another 13A fuse I've gained!!) and it's reassembled and given a nice long soak test.










Another saved from landfill :)

Tuesday 9 April 2019

dbx 160x Compressor - humming and farting.

The famous George called - he's moving studios and could I be on hand to lift some things into a van.

Yeah - why not?

I'll tell you why not - one of the things was a Hammond organ. It weighed more than a small elephant. Three slightly unfit middle-aged blokes and one very fit middle aged bloke just about managed to lug it onto the van. There was a considerable amount of puffing and blowing and cussing! (blatant plug here for The Above Average Weight Band)

Anyway... George had a few duff things for me to look at too, some headphones, a few leads, and a dbx compressor. "It sort of hums and farts" ...



It's a dbx 160X, still in production today, and considered to be a bit of a classic...











The humming is bound to be a power supply problem, and sure enough one of the smoothing capacitors has a bulged top ....















... and a rotten leg. We'll change all four. The unit also has a rather unpleasant case of "glue rot". The glue has changed from a yellow colour to a dark brown. When this happens the stuff can start to conduct.









It's essential to scrape this off to prevent it eating away at the copper tracks, and causing unexpected operation due to the falling resistance of the glue!










There's some rot under the capacitor. I'm not sure whether this is due to the glue or the leakage of electrolyte...










Either way, it's cleaned up and a small coat of lacquer applied before replacing the four 470uF, 35V capacitors with 105 deg types...

Should be good for another few years service now!




Tuesday 26 March 2019

Acer AL1716 monitor repair.

Finishing off the McIntosh last night, and I glanced up at the CCTV monitor on my workshop wall... it's flickering horribly.. I switched it off.

So I walk into the workshop tonight, armed with a new HDD for the computer, as the old one simply hasn't got a big enough swap partition to render my new video (spoiler alert, it's a TV restoration...), switch on the monitor and it just sits there, ticking slightly with it's power LED flashing in sympathy.

Hmm... the power supply's tripping.

I get it down off the wall .... It's an Acer AL1716 17" 4:3 monitor I was given secondhand 10+ years ago. It's served well.








Undo the two screws on the back behind the controls, and remove the back with a guitar pick or spudger...

Remove that bit of yellow tape, and the silver screening tape. Leave it stuck to the LCD panel, and remove the lead to the front panel controls. Remove the four screws holding the electronics to the back of the LCD panel.



Remove the four connectors to the back light, two at the top, two at the bottom...








Lift the electronics a little, and remove the connector to the LCD panel by pushing the small catches on each side of the connector, and gently removing...

Put the LCD panel safely to one side.















Remove the black plastic cover, and all the screws from both controller and power supply board. Remove the two "bail lock" screws from the VGA connector.










Now you can remove the PCBs, and unplug the power supply form the controller board.

The main reservoir capacitor was holding a good charge of about ~90V. I discharged it through a 10K resistor, so it couldn't bite!

Let's play a game of "spot the duff capacitor"



Plenty to start with!

Including this one, whose top was fine, but had let go at the bottom! I decided to change all the red coloured electrolytics.


The repaired PCB, and the guilty parties!



Bingo, another saved from landfill...


Now to change this hard drive!