Dual 505-2: Mini-restoration and first impressions


Those who have read my little review of the Tannoy Mercury M20 Golds might be aware I’ve inherited some other items that they were originally purchased with sometime in 1985, we think. In this little article I’ll be explaining a little about our (immediately) beloved turntable – the Dual 505-2. By modern standards, if purchased new I would guess this record deck would compare with the likes of the Project Debut Essential package or similar. Our example appears to still be fitted with its original Dual ULM165E cartridge and DN165E stylus. We have no idea what playing time the stylus has seen, nor whether it is indeed the original stylus or an after-market replacement.

Fault-finding and repair

Upon arrival the platter would not spin, and I had been warned of the need for replacement drive and pitch-adjustment belts. After some Google abuse in an attempt to find a service or owners’ manual for this unit, I found my way to the Vinyl Engine which had an English owner’s manual available.

Dual 505-2 disassembly/reassembly

After downloading and reading the owners’ manual, I then attempted to take the inner plinth out of the wooden frame. This isn’t as easy as it looks; so having armed yourself with a Leatherman, Dutch courage and a glance at the owner’s manual, it goes something like:

  1. Lock the tonearm in place.
  2. Remove the stylus and put it somewhere safe to save it getting damaged.
  3. Remove the rubber turntable mat, and the platter.
  4. Remove the plastic lid.
  5. Ensure the transit screws are in the “playing” position, to give the suspension mounts full movement.
  6. Turn the whole deck on its back (so it rests with the hinges against your work surface).
  7. Slide the suspension spring bases out of their homes in the plastic base plate. The whole plinth assembly can then separate from the base. Note that the captive mains, signal and ground cables prevent the plinth separating completely from the base, without further work to release the cable entry glands.
  8. Breathe. Carefully.
  9. Reassembly is essentially a reversal of steps 1>8.

Checking the tonearm, motor and microswitch interaction

Another thing I learned during my Google session to find the manual was that one of the most common faults with these decks is that the microswitch seizes up if the deck has not been used for a while.This is the switch that starts the motor spinning when the tonearm is moved into the playing position. The cure recommended on most online forum posts I found on the issue was to simply use a screwdriver to operate the switch enough times until it starts working again. If I recall correctly, the switch is on the underside of the plinth next to the motor, and has either a yellow or blue plastic cap that connects to the tonearm assembly, via a system of levers that I could not easily work out. Within about 10 pushes the switch mechanism freed itself and the motor started spinning. With hindsight it was risky leaving the mains plugged in while I took everything apart, but it paid off and as it turns out there were no exposed terminals that a stray finger or screwdriver could have found. Phew.

Drivebelt check

As mentioned earlier, I had been warned of the need for a new drivebelt. It turned out that the belt itself was fine, but it needed a little gentle persuasion to realign it so it ran inside the speed selection mechanism. I tested the speed selector a couple of times to check that the belt stayed in the correct position, which it did. While I had the deck apart I also discovered that the toothed pitch adjustment belt had somehow snapped, so without any spare parts to hand I simply removed it and hoped for the best.

Function test, and adjust pitch

Having reassembled the deck I plunked down Suzanne Vega’s debut LP, and found both platter and cue mechanisms to work as designed. The result was quite stunning – the aged stylus and cartridge combination was working well enough with the photo stage of my NAD 302 amplifier to extract a remarkably pleasant sound from the disc, albeit at a slightly higher pitch than normal.

So, off came the platter and out came the Leatherman to attempt a quick-and-dirty adjustment of the pitch control pulley. Having worked out that the belt links the surface-mounted pitch control knob to the control pulley on the motor assembly, I could reason as to which way to turn the pulley to make the required adjustment. Using the narrow flat-blade screwdriver on the Leatherman, I turned the pulley through 90 degrees anti-clockwise by locking the blade in the teeth of the pulley and pushing gently in the right direction.

Trying the test LP again showed I’d adjusted too much – the song was now playing slightly slower than normal, so I went back and halved the difference. The LP now played what I considered to be ‘normal speed’ (turns out I do have an intuitive sense of ‘perfect pitch’, though it helped to have a CD of the same album to compare, which did indeed synchronise perfectly both in terms of track length and perceived pitch/tempo.

First impressions of sound quality

This is a subject for another post of its own, I’m sure. What immediately strikes is that the sound quality on offer is surprisingly good, but there are no good words or phrases I can think of to describe how it differs to the same material played from CD or other known digital sources in my system. When the disc is clean and in good playing condition, and has itself been mastered and manufactured well, the soundstage is noticeably wider and deeper than my digital sources, and the overall presentation is simply more musical. It’s not that the vinyl source is ‘warmer’ or more detailed as has become the stereotypical wording used by audiophiles writing in print or online when selling the plus-points of vinyl – just that the overall result is simply more pleasing to me. My wife confirmed this, noting that the vinyl feels more ‘real’, more as if the musicians are being presented in a space around and in front of us, compared with the digital sources forcing the soundstage to be artificially contained within our room.

Stay tuned for more on what work we carry put on this deck, and for some more in-depth reviews of what it enables us to enjoy!

Update @23:42
Put picture back into the post as originally designed, correct spelling/typo’s, add the following list:

Things still to do:

  • Install a replacement stylus in case I broke anything in transport or handling. Turns out the current one (and its cartridge) are replacements with only 50hours playing time on them, but I’ve already ordered a Dual DN-165E replacement stylus from Stylus Plus, so at least I’ll have a spare.
  • Replace the pitch control belt – not because it’s needed in normal operation, but I feel it’s only fitting to bring this one back “to spec”.
  • Check alignment of the cartridge. When I first started using the deck, I noticed a significant amount of sibilant distortion when nearing the end of a side. This isn’t uncommon, but a quick alignment according to the “Stevenson Method” has made things noticeably better at the expense of slightly increased sibilant distortion at the beginning of each side.
  • Clean all our LP’s and replace inner sleeves.
  • Try the phono stage of our inherited NAD 3020B in place of the current NAD 302.

24 thoughts on “Dual 505-2: Mini-restoration and first impressions

  1. UPDATE: Turns out there’s a much easier way to lift the plinth away from its base – the transport locking screws when undone can lean in towards the centre of the platter, which releases them from the spring suspension assembly and allows the plinth to lift off a lot more easily than my rather er, “rock and roll” method described above. The same issue will be met with the captive leads though…

  2. I just picked up a 505-2 myself for a mere $40. Pitch belt was broken as on yours. I put on a Shure test record and played the 1000hz tone, then opened my Gibson iPhone app, which told me the tone was 999.09 hz. Close enough for me. Mine has the stock Ortofon OM5, and it sounds surprisingly good.

  3. I have a B&O Beogram that I have reluctantly accepted just isn’t ever going to work properly – I was lucky enough to have a 505-2 just sat around from when we had it as the shop deck (we run a record shop) – Hadn’t been played for over eight/nine years I guess, slapped in a new cartridge and it sounds great through our Denon amp – Neither are high budget, but good honest sound. I need to track down a test record just to check that it is all calibrated okay, but it gets a 10/10 for me… an old fashioned work horse of a deck!

  4. excuse me how i can replace the pitch belt in my dual cs-505-02?? My pitch belt it’s broken , i find a new belt but i don’t know how to replace it!! help please!!

  5. Just worked on my Dual 505-2 and used the Malvern Audio twin belt replacement for the pitch belt. Does anybody know how to get oil into the main bearing???

  6. This is a nice little write up and the “Checking the tonearm, motor and microswitch interaction” entry came in handy for me today as my switch got stuck. Had my Dual since ’85, neglected it for a while, had to replace belts, stylus and get a new preamp when I took it out of mothballs a couple of years back. It sat this last time for two years and the only problem was the microswitch – flipped it back and forth for a bit and it loosened right up just like you said – so listening to analog this week.

  7. Thanks for the positive feedback!

    That micro switch problem came back about 6 months ago, but was mitigated with some silicone (non-conductive) grease.

    Things have moved on a bit with our deck since that post was written. The mechanics are the same, but I’ve made a number of improvements and have a list of many more that I’ll write up when time and resources allow.

    Our example remains in daily use and we’re still listening to far more analogue audio from LP than digital from any other source.

  8. Oh, and I should note that our deck is apparently still running its original drivebelt from the day it was bought in 1985 – due a change shortly as the pitchbelt has long gone, and the platter is getting slower to come up to speed.

  9. My tonearm is stuck in the upright position. I have to take off the counter weight completely to get the tonearm to rest in a down position. Any suggestions? This is my first experience with a 505. Cheers!

  10. My suggestion would be to check the auto-return mechanism is moving freely underneath the metal plinth. My deck is now heavily modified, and the metal plinth is now sitting on a custom wood/chipboard bottom case. When I first mounted the metal plinth (and all the attached motor/tonearm/automation mechanisms) to the bottom board, I hadn’t given enough height clearance for the underside of the plinth, which meant the arm would either get stuck in the “up” position as you describe, or the arm would not move freely across the disc.

    If your deck is “stock”/un-modified, I’d be thinking to check that springs are in place on the underside of the metal plinth, that they’re actually doing their job, and that the entire mechanism is well lubricated. I’ve used a combination of Lithium and Silicone greases on my deck (much to the annoyance of Dual purists I’m sure) to keep things lubed and moving freely.

    I’d suggest that it’s the weighting spring that maybe has come adrift on your deck, but having never actually had to replace/service mine outside of the height clearance issue that was solved with a chisel on my custom wooden base, I can’t think how to describe/narrow down exactly which spring you’re looking for.

    Sorry for taking so long to reply – holiday and other projects have diverted me from my passions of late. Please let me know how you get on!

  11. One of the channels is being intermittent, cutting in and out. I had the RCA, power and ground wires replaced recently and it did not change the problem. Do you have any idea what this might be and how to fix it?

  12. Great write-up, I have a 505-1, which also has an intermittent fault, i.e. cutting out on left channel, I’ll be using your article as a guide when I open it up to check the connections inside, thanks.

  13. Re. channel-dropping issues…

    1) Have you tried a different cartridge?
    2) Have you cleaned the cartridge contacts and the arm wiring contacts?
    3) In both cases, especially if ground, RCA and power cabling have been replaced, I’d suggest either oxidation of the connections at either end of the arm wiring, or the wiring itself.

    Hope that helps – let me know here if you find a fix!

  14. Ok, fixed my 505-1, looks like it was oxidised connectors on the plate that the cartridge bolts to, cleaned them with cotton wool bud and electrical contact cleaner form Maplin’s, plus a litle gentle scraping, they look bright and shiny now, looked kind of gunmetal colour before, now plays on both channels now and hum has disappeared. Enjoying my deck again now, thanks for the advice.

  15. Ok, fixed my 505-1, looks like it was oxidised connectors on the plate that the cartridge bolts to, cleaned them with cotton wool bud and electrical contact cleaner form Maplin’s, plus a litle gentle scraping, they look bright and shiny now, looked kind of gunmetal colour before, now plays on both channels now and hum has disappeared. Enjoying my deck again now, thanks for the advice.

  16. got a dual 505 second hand fitted it with a brand new ortofon om5 cartridge and stylus but i seem to be getting distorsion on play back especially when the bass comes in on a track the treble side and vocals don’t sound to bad or if you are playing an album of acoustic songs

  17. I purchased a Dual 505-2 turntable in mint condition except the stylus arm does not move to the left to over the turntable. It is stuck. There is nothing visible on top to explain why the arm won’t pivot. Any thoughts?

  18. I’d be checking the auto-return mechanism isn’t getting jammed – I had that happen with mine a couple of times when I put it on a custom plinth without checking the mechanism clearance first!

    If yours is in its original plastic/fibre/chipboard bottom-case, I’d be checking for correct lubrication all round..

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  20. Hi there!
    Can I get some advice on this model from you guys? have been looking into buying one of these. There is one in PERFECT condition, fully functional and the price is $150 CANADIAN. Is that too pricy? I’ve heard mixed reviews on the Dual 505-2. Also, please excuse the fact I am such a newbie, but can this simply connect to a receiver and be good to go>? Does it have to be mated with a specific one? Is there any reason certain models need amps + tuners instead? What will I need to make it play.

    Thanks so much!!

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