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Sunday, 4 July 2021

Luxman R-1040 Repairs and restoration.

 Look at it..... 


...Just look at it...

What a thing of beauty. A joy to behold. 


It's a Luxman R-1040 receiver, dating from 1978.
I'm somewhat jealous. A quote from Hifi Engine "It has a genuine output of at least 40 watts continuous per channel into 8 ohms from 20Hz to 20,000Hz with no more than 0.05% total harmonic distortion." That's a very fine spec today, let alone 1978.

This one belongs to cheerful Martin, and has issues. It makes a noise like the tide going out when it's first switched on, some of the lamps have failed, the pots and switches are all scratchy, and Martin would like it re-capped. No mean feat. 

Right, let's crack on... 

There are 6 fittings, which look like they'd be perfectly at home on some Ikea furniture underneath. Remove them with the receiver on it's side, and simple slide the whole chassis out. Put the wooden cover somewhere out of the way, where the cat won't use it as a scratching post.
... it's almost as good looking on the inside as it is on the outside... look at all the space (are you listening Aurex!) 

Access is generally easy. We're going to need to remove the power amp board from the output transistors, and the volume control board to gain access to some of the caps thereon, but it's all very nice.
It appears a cap has let go in the past, as there's some debris... 










A quick look at the service manual and some nice Nichicon caps are on there way. (I would have gone with OE Nippon's, but the price!! I'm damned if I'll pay over £50+VAT each for some of them!) 

You've got to love the march of technology! The new cap on the left, which has a better specification than the old on the right...










The output transistor's heatsink is removed to facilitate change of capacitors, and the output transistors marked up, so they go back in the same order, and the old heatsink grease cleaned off and replaced with thermpath. 









There's a considerable number of caps in this unit, so it takes some number of evenings to complete.










Martin mentioned he wanted the dial lamps replaced, as one had failed... 

This necessitated removal of the front panel...  

.. and the dial glass. 











Despite the remaining dial lamp shining a white light, when it was disassembled, There were two green caps, which had faded / melted with the heat. The original illumination would have been green.









The white wire is disconnected from the power supply tag pin 10, and a 1N4007 diode and a 470uF capacitor are fitted to switch the supply to DC, so we can fit some appropriate LEDs easily...
















... nice...












Bias is set for 45mA (after a minute or so's warm up), DC offset nulled out and the pots and switches cleaned.











And finally all buttoned up and tested. 






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