Linn Karik / Brilliant Power supply repair.

Colin called by en route to the traditional Wednesday night curry....

"Got a Linn CD player here that's not working. Can you have a look?"

Yeah ... why not.

It's a Linn Karik.

I give it some power and load a CD. It fails to read the table of contents.

It then goes dead...

A couple of power cycles, and I manage to get my disc back out...

Right, Removal of four screws underneath, and slide the cover off, praying I don't see the dreaded "Brilliant" power supply ....











Oh gawd...













These supplies were sold as an "upgrade" (because Linn ownership is all about upgrades, right?) It's a switched mode in a toroidial shaped metal box, designed to fit where the once perfectly adequate, perfectly reliable mains transformer lived...

First things first, remove the nut securing the supply to the chassis from below, and lift out the supply. Undo the mains input from the input PCB, and the output to the main chassis.

Now remove the three shiny outer screws from the enclosure. You'll notice the foam washer has been cut away here, to expose three nylon screws. This means that (unsurprisingly) someone's been here before!

Right, now a note of warning! This thing always seems to remain charged up. Be very careful not to touch the PCB's, until you've checked there's not a cap charged up to a few hundred volts waiting to bite!



You can now extract the PCB's from the enclosure. You'll need to work the strain relief grommets down their slots a little to get them free...

Instantly I noticed that familiar smell of capacitors that have been too warm :(






We now need to remove the three nylon screws from the base plate. If your foam washer is still intact you'll need to remove a bit to get to the screw heads.










You can now separate the boards. Those two large electrolytics on the right are the ones that tend to hold their charge! Discharge them before they bite!

Now change out all of the small electrolytic capacitors. All of them.

You'll need:
1 x 33uF 35v
1 x 100uF 35v
1 x 220uF 25v
1x 47uF 16v

Get quality 105 degree rated caps from a reputable supplier.

In about 25% of these units, you will find you can now reassemble and it'll work :)

This one was a little stubborn. After a bit of head-scratching, it was found that the UC3825DW controller IC has failed. A replacement restored operation... nearly...

The servo was struggling to lock, discs were prone to skipping. A sure sign of a tired optic assembly. Cleaning the lens made a marginal, but inadequate improvement. A new one (from a reputable supplier) was duly fitted, and had the player working well :)

"There's never one when you want one, then two come along at once" Linn Wakonda revisited.

Here's something I'd never thought I'd see again....

Remember the post about the rare Linn Wakonda LP12 power supply (here) ?

Well, John tracked me down (internet, eh?) It turns out he's got another one (and turns out to be a mate of a mate of a mate, twice removed...)

"Hi Andy

are you able to repair a linn lp12 Wonka pcb...its been working fine but has developed a problem where the motor stutters and jerks once its switched off

is this something your could help me with?"

Yeah ... Why not?

He's seen my blog post, and has done the cap change as I had, but still no joy.

Now this sounds very familiar to a failure on the Linn Axis (of evil) power supply where the speed selection logic goes screwy ...



It duly arrives from that bit of the UK right at the top.

Sure enough all the caps had been done (bar one), and a tidy job it was too :)

Despite the remaining cap being OK, I replaced it anyway.

Tracing the speed control logic through proved one of the counters had forgotten how to count. It's U15 on the board.



Replacement provided a cure...

Wrecked Akai M-8 conversion to mono-block amplifiers.

Edward phoned..

"Got this ruined Akai tape recorder. Do you think you can remove the amplfiers and turn it into to a couple of mono-blocks?"

Yeah, why not...

Edward turned up one complete tape deck , and another two amplifiers, which are almost identical, but badged "Roberts"

One of the Roberts amplifiers has apparently got a duff output transformer in it....

This is what an M8 is supposed to look like... a bit of a Japanese Ampex look-a-like.

I didn't take a photo of Edward's, but it looked similar to the above, except it appears to have been dragged across a car park...

I removed the deck ...
Levers are bent, spindles smashed :(











I also remove the amps, and set to work on a re-cap...

The Roberts unit has been severely got at. Someone's had a go at re-inventing the wheel. Parts are missing, it's been totally re-wired. The other has a damaged VU meter. It's decided to leave these.






Once the two other amps are re-capped, and permanently switched to "record" , enabling a line level input to be amplified, and output. It's only a single-ended EL84, so it's not expected to produce trouser-flapping levels of volume.

I've added a couple of warm white LED's behind the grills on the front panel to illuminate our valves a bit..








Being of Japanese extraction, the whole thing was designed to run from 100VAC, so export units had a built-in autotransformer. This is removed from the case.









My friend Julian fabricated some nice enclosures from MDF.

... which I painted the underside, inside and rear panel black.












... and set about adding some veneer ...

 ... and a test fit ....

 Smart!

 ... and adding many layers of finishing oil

 To achieve a shiny finish!














A phono socket and speaker binding posts are added to each unit ...

Finally assembled.













Next the auto transformer is mounted into a small ABS enclosure.

Which feeds the required 100V AC to the amplifiers via 2 IEC leads.










All tested and ready to return home ...

How's it sound?

I'm surprised. It's not loud by any stretch of the imagination, but it has some real bass control, which is unusual given the tiny output transformer. Use some efficient speakers and enjoy!

Philips Digital Compact Cassette recorder repair DCC 951

I missed out on the whole DCC thing. I was a big fan of minidisc...

Anyway, this found it's way into my possession....

It's a DCC 951, dating from 1994. It doesn't work. It's totally dead.


Off with the lid ...

Poking around with a multimeter proves there's AC on the output of the transformer. Time to examine those "wickman" fuses on the rear PCB...











Which involves removal of the back panel, which is easy enough... a few torx screws, and bending these little tabs out of the way ...











One on each side...

.. and lifting the panel off. The mounting screws can now be removed from the PCB, and it can be hinged up without disconnecting anything...










Sadly the wickman fuses are all intact ... but the regulators on the heatsink are horribly dry-jointed, and a quick solder up on these, and the mains input socket and switch (which are also looking poor) , solves the problem!











Great front loading mech... really smooth!

A conventional analogue tape can be used (analogue only, sadly), and goes in with the exposed side forward. Sadly I don't posses a DCC casette to see what the digital bit's like.

I clean up the tape path, and change the loading belt (it was OK, but I had a new one to hand!)
DON'T DEMAGNETISE THE HEADS!




Here's a few other shots...

... now to find a cassette ... anyone?

It's (another) Arduino Christmas.

Here's a super simple persistance-of-vision display.

Drive the neighbours mad with 8 static leds, that when they move their head, or drive past, delivers a festive message!

Ingredients.

1 Arduino board (I used a 3.3V 8MHz mini, but anything will do)
8 LED's (if using a 3.3V board, make sure you have enough voltage to light the LEDs!)
8 current limiting resistors

Connect each LED to pins 0-7 (noting 0 and 1 are RX and TX) via a current limiting resistor, and ground.

Load the code from https://github.com/andydoswell/christmas-POV

and enjoy the festive season!

And here's Stuart W's version!