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Thursday 2 February 2017

Linn Axis (of evil) repair

Belated happy new year readers!

Been a really busy January, and I've not had much time in the workshop. I've completely moved a radio station for a charity, and it's been stressful! (more on that in a forthcoming post)

Anyway, Jon rang. A fine cycling chap from Bristol. Got an Linn Axis that won't run....

Can you take a look?

Yeah, why not...


It duly arrives sans platter and stylus.

I plug it in , and sure enough the motor just stutters... which is pretty usual for one of these.

The motor drive board will be faulty. Now there's much BS on the interwebs that these boards aren't repairable as "the programmable parts are no longer available" .... which is rubbish, as there aren't any.... someone's probably just trying to flog you an upgrade ... and Linn ownership is all about upgrades , right?

It's just a bunch of logic, and some op-amps...

This board is quite an early one, as it's got a ribbon cable to the speed/on/off switch which is soldered straight into the board...


So. Remove the sub platter and belt. Clean up the inevitable oil spill from the bearing. Now move the turntable to the edge of the bench, and remove the three large suspension screws holding the top plate to the rubber suspension mounts. If you're doing this with the arm attached, remove the cable strain relief first. Lift up the front edge of the top plate a bit and have a peep underneath. If your switch is attached by a coloured ribbon cable, then you'll need to pop the switch out, and slide it back inside. If it's a copper coloured flexi, (like Jon's below) just disconnect it from the motor drive board. Lift the top plate clear and put it out of reach of the cat.


Now remove the 6 small screws indicated by the red arrows, and the mains lead from the terminal block on the bottom right.

With a bit of jiggling, you should now be able to extract the board. You may need to squash one of the suspension mounts a bit to extract it.






Now change every last damn electrolytic on the board, even the high voltage ones.

Here's the shopping list:
2 x 33uF 350V axial
2 x 47uF 250V axial
2x 220uF 16V axial
7x 22uF 50V radial.





Now a word of warning.... this board is "live" when it's connected. So use an isolation transformer when doing any fault finding on it. With a bit of luck, you should now have a running board.. however, I have seen turntables with D2 & D3 open circuit, BR1 short circuit. A real head scratcher was one which intermittently blew fuses, which was one of the BUX85F output transistors!

Now if you switch the motor on without a platter and belt on, it will spin up, and then stall a few seconds later. This is usual. Once the platter is on, it should work fine.

.... of course Jon's wasn't going to be so easy, and also needed an LM324 quad op-amp replaced to finally restore operation....

I've seen forum posts saying just change the small caps....... change 'em all. These had been in there since 1989 and were shot away!











Once it's all happy, put the top plate back on, do up the suspension screws (not too tight) and replace the strain-relief on the tone arm wires and check the speed (you really need the top platter on when doing this)

Speed is adjusted using an INSULATED screw driver through two holes on the underside. They have bungs in them, you'll need to just pop those out, and replace them once happy.


Now Jon ... where's your stylus?

UPDATE March 2019! ...

Colin's just popped round with another Axis with a common problem after recapping .... motor spins backwards or not at all or just sits there vibrating. Usual causes are the two HEF4013 flip-flops hanging a line up. Change 'em both. They're just by the switch cable, and are U1 and U2.

Other frequent flyers are the two watty 15K resistors, R2 & R3. With these faulty, there won't be 35V across C5.

Have fun all!



37 comments:

  1. Welcome back Mr D! We missed you.
    Not much to say here, excellent article and all is needed is a decent MC cartridge. Much fun reading, thank you.

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  2. Hi Mr D,
    I belonged to an after school electronics club circa 1981 building projects from etched PCB's following projects within 'Everyday Electronics'magazine and thoroughly enjoyed these.

    I have always been interested in HI-Fi and have owned Linn & Naim equipment up until a divorce in 2010 put paid to this.
    I recently bought a 1987 Linn Axis turntable that would not run but following you blog, I changed the capacitors (only High Voltage ones) and it is now running like new!
    thank you ever so much - I really want to get more involved with such upgrades and look forward to further blogs and info via your website.
    Best regards,
    Geoff

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  3. HiYa Doz,

    I've had my Axis from new since the late 80'5 after upgrading from a Rega Planar 3. A few years ago I swapped my Axis with my Dad, who had a Sondek. His hearing was going (actually turned out to be dementia) so he thought I'd appreciate the Sondek and he was fine with the Axis. My Dad died from Dementia two months ago and weirdly the Axis (which I got back after my parents was sold) developed the speed fault at the same time. Partly sentimental and partly 'cos it's an awesome deck I followed your advice and replaced all the electrolytics. Worked first time and she's rocking again! Speed tested and after a bit of tweaking back at spot on 33.333. Dude, good job! Last time I wielded a decent soldering iron in anger was my 'A' level electronics project when I was 18, I'm now 56. If I can do it, so can anyone. So, great blog, great advice. Dad would be happy. Cheers, Steve

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  4. Followed your instructions and my Axis is alive again. The only "issue" is that when switching to 45 it takes about 10 seconds before the speed change happens. Is this normal?

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    1. This comment has been removed by the author.

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    2. It's a new belt. It continues to turn at 33 once the green light comes on and after 10 seconds you can see a sudden acceleration and it moves to 45. Once up to speed it works perfectly. I replaced the 4 high voltage capacitors first and noticed this issue when testing. I then removed the board again and replaced the other 9 capacitors and still the same. It's not a big problem as it won't be used for 45s but thought I'd share the experience.

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    3. The manual states that 8 seconds to get up to 45rpm is normal. I’ve had two Axises that did exactly that. Switch to 45 and they start running at 33, then accelerate up to 45 a few seconds later.

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  5. Andy, I wonder if you can help me please. I just reassembled my Linn Axis, which has been boxed for 17 years. I bought a new Thakker belt, turn it on an hey, no, no, no! The speed is irregular and there appears to be a bit of a scraping sound as it turns. If I life the spindle, twist and replace it, then the sound goes away temporarily, which suggest an oil issue. This does not explain the irregular speed though. I found a 2011 Aussie article https://www.stereo.net.au/forums/topic/33726-linn-axis-speed-problem-fix/ that talks about changing capacitors in a similar manner that you did. The only problem is that I dont know who to turn to for a fix, because I'm not an electronics buff - would you take a look at it for me please? I spoke with a Linn specialist who told me "they don't make the parts any more, we can cannabalise it for parts and transfer them on to an old LP12 chassis - I ain't got that sort of money to spare unfortunately! Thanks for reading this.

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    1. If it's a scraping sound, it's most likely your motor is toast. It's only a 120V Premotec motor, I'd start by changing that first. Buy a motor online, not Linn's inflated prices. For some reason I hear the "the parts aren't available" line very often. I'll say it again... EVERY SINGLE PART IS STILL AVAILABLE, NEW, TODAY! I'm not in a position to take on repair work at present. Perhaps you have a local TV repair place that you could take it too, and show them this article?

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  6. Great response - thank you. I guess your father would be proud and happy that his turntable is still bringing happiness.....
    Regards,
    Geoff

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  7. I have replaced all of the caps on my Axis board, only to find after 6 months I had the same problem again. Replaced the board with a new Hercules 2 board - an easy fix / upgrade care of Stamford Audio. My Linn Axis is like a new bunny and playing vinyl like out of the box new......….

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  8. I own a Linn Axis turntable (one owner, from new, 20-30 years), which takes extra seconds to begin turning when turned on. Is this a problem? If so, do you know a service person in Rochester, NY?

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    1. Sign of an impending problem probably. Have you changed the caps over? Sorry I don't know anyone that side of the pond.

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  9. That's hell of a lot of good advice. Many thanks!!!

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  10. Thanks for the information, that should help a lot.

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  11. I have inherited my father's Linn Axis turntable he bought brand new in 1987 when he died in 2004. I had already moved from the UK to the States prior to that so I had it shipped out to me. Its only now I am wanting to bring it out and use. Will it simply work at 120V? Underside of the unit suggests so but I'd thought I'd check first. Hope you can help. Thanks in advance.

    Chris

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    1. Yep, just switch the neutral connection to the 110V tap, off you go.... Make note of those caps though, they may well all be past their best by now...

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  12. Just got hold of a axis, previous owner hasn’t used in best part of a decade, has similar issues with scrapping sound, it seems as though it is literally rubbing on the outer frame? Any ideas as to why this would be?

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    1. Check the motor hasn't come unstuck (motor mounting stickers are available), and also check to see if the suspension is in the right place. I saw one where it had been stored on it's side, and the suspension rubbers were all distorted!

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  13. Hi Doz, I have a vintage Linn Axis (1987) almost identical to the one pictured above.
    I believe the motor is shot as it has a rough feel when turned and has a noticeable amount of radial play in the shaft. I see you mention the "120V Premotec motor" above, do you have a part number as well? When I Google it, one comes up as 250 rpm is that correct? I will also overhaul the power supply, changing all the caps etc. Any help will be greatly appreciated.
    Many Thanks
    Eddy

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  14. 250RPM @ 50Hz... measure your original shaft, and ensure you get the correct diameter. These motors have flying leads, so you'll need to account for that, and get a new sticky pad.

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  15. Hi Doz, I have a dead Axis and am in Swindon. Would you have a look and where are you please?

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    1. Hi Kevin, Sadly not, see "Not a business" in the right hand bar ... reply to this with a phone number or email address (neither will be published here), and I'll put you in touch with someone very competent near there ...

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    2. Hi,
      Thanks for such a great site and useful information. I have just acquired a Linn Axis turntable with problems. The unit is in brilliant cosmetic condition. The issue I have is the power board keeps blowing the 400 mA fuse as soon as power is applied, I am unsure if this is caused by the points discussed above or if it is something more sinister. Would it be worth ordering and changing all the capacitors on the board? The other alternative would be to buy a Hercules 2 and install this, but I would much prefer to get the old board working but would really welcome some guidance. Many Thanks Robert

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    3. Certainly start there, if those two caps that form the power supply smoothing are leaky, that'll certainly let the fuse go. If the fuse is blowing violently, check the bridge rectifier and the output transistors for a short. Some boards are fitted with a varistor (v1) , which can fail causing the fuse to open. You can temporarily snip it out, and re-test. Replacements need to be correctly rated (see the valhalla pages)

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  16. Dear Andy,

    I’ve had contact with Johnnie from Audio Origami about my Linn Axis powersupply, and he told me you’re an expert in this stuff. The problem with mij Axis is the fact that I can’t get the 33 rpm at 33,33. It won’t get any slower than 33,41. The 45 rpm works fine. The 33 potentiometer seems to work fine, because higher revs is no problem.

    In the past someone has already changed most electrolyte condensators

    C1 and C2 original 47uF 250 V 85° Replaced with Vishay, same specs.
    C8 and C9 original 33uF 350 v 85° Replaced with Nichicon, same specs
    C3 and C5 original 220uF 16 V 85° Replaced with Nichicon 220uF 25V 85°
    C19 origineel 2.2 uF 16V STC tantalum replaced with 1uF 100V 105° J.D. Elco
    C4, C12, C13 22uF 50V 85° Are still original
    C6, C11, C16, C17 original 22uF 50 V 85° Replaced with 22uF 100V 105°

    Q2 looks a bit strange.

    Could you tel me if there is a possible relation between the difference in specs, especially for C19, and the high speed?

    With kind regards,

    Klaas



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    1. Don't sweat about the specs. My hatred of solid tant capacitors is greater than the electrolytic. I would have replaced it with 2.2uF, but none of this should effect speed. The speed controller works by first setting 33rpm, the 45 rpm setting is switched on top of this, which you clearly cannot do, so we need to look there. Firstly check that the ground connections on the replaced capacitors are good. Check the soldering on both sides of the board. Next we need to look at the control loop. Check the value of R37 , the 33 rpm pot, and R38. I suspect they will both be fine, but we need to rule them out. Is the 45 rpm led illuinated (even slightly) when in 33? Reply here , we'll sort it :)

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  17. Hi there! First of all, thanks for a great resource. I followed your instructions a couple of years ago to replace all the electrolytics and managed to get my Axis working again, just perfect. But now, we've just experienced a lightening strike at the house which killed a PC, numerous smart devices and a swimming pool controller, a lot of damage. Worst of all, my Axis is dead again! No lights on the switch, not even a twitch of the motor when connected. I'm completely lost as to where to start fault finding. The on board fuse is ok, that much I know, also there is no obvious damage, burn marks etc. I'd hugely appreciate any ideas, even if it's 'bin the board and replace it'! Cheers for reading! Steve Jones

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    1. Hi Steve, Do you have an isolation transformer & multimeter so we can make measurements safely?

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    2. I'm afraid I don't, sorry. A quick update, I found that the onboard fuse had blown, I replaced it and it blew again immediately the mains power was applied.

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    3. It's not safe to work on one of these without a transformer, but you can easily make static tests. Check the bridge rectifier for a start, as it's right in the firing line for a lightening strike, and failure will cause very aggressive fuse failure. Output transistors will also cause aggressive fuse failure. If you don't feel confident doing this, I have the name of someone that will sort it for you (if you want to go this route, send me your email address on a NEW thread (replies are auto published, and i doubt you want your address all over the web!) and I'll put you in touch.

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  18. Have followed instructions to replace all caps. Speed on aging Axis is 33.6+. can I get it better using two screws underneath. And how to adjust them? Cheers.
    Alex

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    1. Fully reassemble the unit, including the platter. Support the turntable on the edge of table, and remove the two rubber bungs underneath. One adjustment is for 33 1/3, one for 45. Use a strobe or mobile phone app to set the speed using those screws. USE AN INSULATED, NON-METALLIC SCREWDRIVER! TBH, your 33 RPM is near enough....

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  19. Hi Doz, this is Kevin and I previously posted in April ‘21 asking for help. Sadly your contact never did respond but finally sent my board to an on-line repairer. Received back last Thursday. Now setup and spinning my old records, brilliant. This is a one owner deck from new and it’s great to be back.

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