Linn Ikemi CD player

[Michael Maurice]

I've been asked to repair one of these with a dead power supply.

The power supply is the Linn Brilliant SMPS in the rectangular box. Several transistors are short but without a circuit diagram and parts list, I can't repair it.

Does anyone know anything about these?

Linn no longer supply them and won't supply me with a diagram (if one is available)

Any help will be gratefully received.

[D_S_J_R]

Oh lord... The Linn site is no more but loads was posted about some of these 'Brilliant' smps supplies.

The 'tin can' 'Brilliant' was I believe, a commercial unit, but no idea about the later type. I've been out of it for a while so have no idea how Linn's long term support cut-off works these days (I was told by a current dealer last week that it's pretty vicious when the time comes).

You could try DIY Audio forum and definitely the 'Linn room' on HiFi Wigwam, but in the meantime, I believe the set thing was to replace all electrolytic caps with modern 105 degree (or higher) ones regardless and maybe the MOSFETs? on the output.

Apologies for not helping more. Hope you can get somewhere as the Ikemi was nice to use and with a slick CD transport that worked well when new twenty years or so ago.

[Michael Maurice]

It would appear that the circuit diagram may be a closely guarded secret!

if i knew what the outputs were, I may be able to fabricate an analogue one!

[michamoo]

Some information on this page but you may need to join to see it.

https://www.diyaudio.com/forums/anal...atic-smps.html

[Radio Wrangler]

Excluding some weird mag amp types, an SMPS with one transformer can only regulate one output using pulse width modulation. Other outputs are pitched a bit high in voltage and then reduced with linear regulators. The output with the feedback connected to it is normally the one with the highest load power.

If they haven't ground the type number marking off of the SMPS control IC, you can look it up, find the feedback resistors, and from their values and the data sheet calculate the voltage of the main output. Similarly the outputs with linear regulators can be determined.

If you did make a nice linear supply replacement, you could build several units and flog them as upgrades. Don't forget to charge Linn-compatible prices

David

[Craig Sawyers]

Originally Posted by Michael Maurice

I've been asked to repair one of these with a dead power supply.


Linn no longer supply them and wont supply me with a diagram (if one is available)

That is shocking after sales service. Try emailing Ivor Tieffenbrun.

His email address is in his LinkedIn profile.

So worth a bash.

Craig

['LIVEWIRE?']

Linn aren't the only ones who won't supply service info. or spare parts. Mordaunt-Short are another. Some years ago I contacted them for info. about an active sub-woofer. Their response was along the lines of 'all M-S equipment has to be returned to us for servicing' No doubt there are others, too, who take that attitude. Perhaps we should have a regulation in the UK similar to that which, AFAIK, still exists in Germany, where all new radios, etc., had to be supplied with at least a circuit diagram.

[Ted Kendall]

Originally Posted by Craig Sawyers

That is shocking after sales service.

Indeed. How nice it is that in these times there are still firms who can afford to lose return customers hand over fist.

[Radio Wrangler]

If proper service information was released, some people might notice that there wasn't actually any magic fairy dust inside at all.

Some firms restrict data on their products almost as if they were protecting rocket fuel formulae and atomic bomb details. You'd wonder who they are protecting it from. Are Natasha, Boris and Dr Fu Manchu just itching to get their hands on such secrets? Nope. I think the people being kept in the dark are actually their customers. Their competitors can already design perfectly satisfactory products.

The true believers amongst their customers would likely just see it as an excuse to 'upgrade'

Kat Manton did a nice job in tracing out one amplifier. There was nothing magical in it. Tracing out this PSU would be a service to many.

David

[Michael Maurice]

Originally Posted by Craig Sawyers

Try emailing Ivor Tieffenbrun.

His email address is in his LinkedIn profile.

So worth a bash.

Craig

Ivor is no longer chairman of Linn

[DonaldStott]

Originally Posted by Michael Maurice

Ivor is no longer chairman of Linn

Gilad Tiefenbrun, son of Ivor, has been the Managing Director at Linn Products for some time.

Don't get me started on the the company's focus in recent years on "Lifestyle Products"!

@Michael - in relation to your O/P I've sent you a PM.

[Chris55000]

Hi!

Here's the PSU information I got off the DIY Audio Forum – the chap put a lot of hard work into drawing this out but he's spread it out unnecessarily over numerous sheets, drawn things upside–down and at all sorts of strange angles, etc!

If you'd like me to do a revised clearer drawing, please let me know!

Chris Williams

[FERNSEH]

Info about the control IC here: http://www.ti.com/product/UC3825

DFWB.

[Radio Wrangler]

IC1 and the triac form an automatic mains voltage range switch, selecting bridge rectifier or voltage doubler mode for the input circuit. Anything wrong in one of these can get rather dramatic. Very expensive Sony 21" computer monitors (sometimes OEM badged) had a design fault where theirs sampled the mains, made a decision and locked in that mode. They could be fooled by a brownout. When some neds threw a length of wire rope over an 11kV rural line, most of the monitors in a large firm blew up. About three quarters of a million worth of them. The mains hadn't gone overvoltage at all, it was the recovery profile that foxed the range select switching.

I was told that some of the larger (and maybe earlier) Linn amps had power factor control. This doesn't it's a rectifier into reservoirs circuit.

Beware of those ground sybmols in little boxes, they look to be the high voltage DC negative and will be at a dangerous potential with respect to real earth.

The second page shows the Half-bridge switching transistors, primary of the power transformer, and the gate-drive transformer.

Page 3 is the switcher control IC.... Whoever drew these diagrams shows some components multiple times - duplicating stuff on different pages so the driver for the gate drive transformer primary can be seen on page 3 and also again on page 2.

Page 4 Oooh! tantalum reservoirs! Three of the perishers.

It isn't very clear how the SMPS chip senses output voltage to achieve regulation.

David

[Refugee]

When I worked with computers we used to rip the triacs out of those voltage selectors to stop jobs bouncing.
They were dreadful.

[Chris55000]

Hi!

New & clearer format circuit diagram now started and will be posted when completed - I've already had one requested!!

Chris Williams

[Trigon.]

Originally Posted by Radio Wrangler

It isn't very clear how the SMPS chip senses output voltage to achieve regulation.
David

'13v7' @ top right page 3 goes to error amp network top right page 2.

Cheers

[Radio Wrangler]

Thanks, Trigon.

That's well hidden!

I suppose it gets reasonably load-independent dynamics because the main load on the 13V7 supply will be the gate drivers on the control chip.

I don't see anything brilliant in this design, but then I'm not a marketing department.

An iron transformer job would have been simpler and more reliable. The efficiency difference shouldn't be significant in a preamp. The SMPS doesn't do PFC. I suppose all it saves is a mains range switch for uusers to get wrong.

Thanks,
David

[Michael Maurice]

Thank you to everyone who has contributed to this.

My example is the Brilliant Slimline which appears to use one device as the main switching device, a VB408 which is no longer available.

The unit is rated at approx 20W.

Also my power supply has 8 wires from it whereas the one in the diagram has 5 it looks like a 6 output unit judging by the number of ferrite bead links.

So back to square one I'm afraid.

[Chris55000]

Hi!

The VB408 wasn't a switching device, it's only an LM317 type circuit made to withstand up to 450V h.t. Voltage differential!

Have you tried using the Supertex/Microchip LR8 with an additional small high–voltage pass transistor between the LR8 and the load?

Something like an MJE340 with C to the H.T. input, B to the LR8 o/p and E to the load?

The original VB408 was only limited to 40mA max – you might get away with an LR8 if you clamp it to a heatsink – the LR8 is rated 30mA!

You can also get discrete H.T. regulator PCB kits that will operate up to about 450V as well – one of these might get your unit working if there's enough room inside!

Chris Williams