Fook Lever

This from the Yamaha P-751 service manual:

Fook Lever

I always wondered where the fook lever was.

Now I know.

Just bought a Yamaha P-751 for $20 on Trademe. The seller said it had just stopped working. I plugged it in, nothing. I noticed the fuse was blown, replaced it, the turntable spun for two seconds then stopped, fuse blown. Ahem…on the back the words ‘120 Volt’ stood out like dog’s balls (a particularly antipodean expression). Somebody had replaced the plug…I scavenged a power cable and moulded plug off a lamp, replaced the turntable cable and fuse, plugged the turntable into my stepdown transformer…and it went! Phew…the fuses must have saved the Yamaha’s transformer. Speed wouldn’t change…I looked at the PCB, and decided to test R15, the first component after the 33/45 pin. It was meant to be 100 Ohms, but was meg Ohms. Replaced it, speed changes now. I’ll do some work on it (probably replace the X capacitor across the AC line, it may have taken a hit) and it will go to a friend who wants a turntable. Fully automatic quartz-controlled direct drive. Nice-looking, nice-sounding and with ADJUSTABLE VTA, something you don’t see every day.

Advertisements

How to Land the Space Shuttle from Space – Bret Copeland

Just a truly great video – entertaining and informative. Thanks Bret! I guess there are valid objections to the shuttle program – it was born out of a political compromise, reusing the shuttle actually cost more per launch than the Saturn V/Apollo flights, it only flew into Low Earth Orbit, it was the deadliest space vehicle, etc. etc. But I still love the shuttle (or do I mean the orbiter?) – an amazing engineering achievement, and it did, after all, enable the building of the ISS and the launch of many satellites, including Hubble. And the people who flew it seem notably brave and capable. So, hats off…

iPhone 6 Plus LCD

Today, what a day! I replaced the screen on my friend Mike’s daughter’s iPhone 6 Plus. I’d never done one of these before and REALLY should have done a bit more research. However, with tools in hand and iFixit video cued up I embarked on this at 10:30am. It was not to prove simple…the main problem was battery removal: I heated the back of the phone moderately, pulled at the adhesive strips – and promptly broke them. I cut a thin piece of plastic and pushed it under the battery, slowly and surely levering it up and pulling away the adhesive. When I got the battery out I saw I’d broken the outer covering, and could smell the sweet-almond scent of electrolyte (cyanide? only wish it was!). I realised the battery was trashed. I continued, and tore the home button flex that runs up the back of the digitiser shield. I thought, I have to finish this today (customer is 16 and would die without her phone) so rang the first place I found and collected a new battery and shield + flex. It wasn’t Trademe, or ebay, cheap, but a retail outlet has a right to make a profit, nawmsayin’? However, Wellington Phone Repair at 37A Taranaki Street Wellington, New Zealand, was a perfectly obliging and amenable outfit. I chatted with their tech guy about the ins and outs of battery removal, then went next door to the skate shop retail area and bought my replacement parts. Thoroughly nice people, I haven’t had them repair anything but their down-to-earth friendliness and helpfulness leads me to believe they’d be worth checking out if you need something done to your phone. Back in my ‘workshop’, I did part of the repair then went to help my friend Alex set up the Lumia 930 I’d sold him. With mind reeling from downloading, installing and explaining I went back and completed the repair, which by some small miracle seems to be OK. The daughter has a friend who needs the same repair done to the same model iPhone, but I think I’ll have more of a clue about the 6 Plus the second time around. Here’s hoping…

Tonight I tried removing the battery from a broken iPhone 6 I’ve got in the drawer. I removed the vibrator motor (I think that’s what it is at the bottom end of the battery) and could see the broken-off ends of the adhesive strips under the battery. I used tweezers to grab one at a time, pulled gently and wwwrreeeeeaaaaaatttttttt (that’s a rough approximation of the sound they make) they came out, battery released! Note to self: always pull the adhesive SLOOOOOWLY!!

Lumia 930 vs. Lumia 1020

The 1020 has been my daily driver for some time now. I love Windows Phone, it’s very simple and elegant. I understand the app gap drives a lot of potential users away, but I really don’t understand people’s unthinking aversion to it.
I bought a broken 930 recently for $44 and replaced the screen. I’ve got three in a drawer with various problems, mostly microphone-related, and this is the first fully-functioning example I’ve laid my hands on. It feels a bit slick and soul-less compared to the 1020, but it’s running Windows 10 so is a bit more functional in today’s terms. The camera has only half the pixels of the 1020, but the results seem OK to me. First impressions: Elegant hardware and slick software, a nice phone. I’ve joined the insider program and a new build was installed on Saturday night. Everything seems faster and I’ve noticed some additional features in the camera app and Edge browser. Watch this space…

So after a few days of using the phone I’m kind of bowled over: Never misses a beat (I think it crashed once, when I was trying use dictation in a poor reception area), 4k video, slick, usable – even has a wireless charging back built-in! Amazing phone, even in 2017.

Replace the broken pitch belt on your Dual CS-505 for FREE (almost)!

A missing or perished pitch belt is a common ailment on these turntables, maybe because nobody uses the pitch control and they rot away! It’s an odd feature to have on a turntable that has no strobe lamp – I’ve only worked on the CS505, CS505-1, CS505-2 and CS505-3, so maybe Dual fitted one to the later incarnations, I dunno.

I’m currently servicing a CS505-3, and it doesn’t even have strobe markings on the platter as did the earlier models. It DOES have a 45 adaptor with markings on it, so maybe I shouldn’t complain. Strange that quite humble Japanese turntables will have a fully-featured pitch control…er…feature (knob, platter strobe markings, lamp) so this bit of ‘German Engineering’ beats the hell out of me.

Replacing the pitch belt isn’t absolutely necessary: it’s possible to set the pitch with a strobe disc and spanner – you just turn the nut on the pitch adjuster assembly on the top of the motor. However, if you do decide to replace it, toothed pitch belts can be pricey. Turntableneedles.com has them for around NZ$40 landed here. There are alternatives – Malvern Audio sell a kit of two non-toothed belts, but this would have set me back nearly NZ$50 including shipping. I tried using two small belts, and they worked but would slip off the motor adjuster cog and jam it, so weren’t ideal.

I had a brainwave today and tried a zip tie. I chose a clear, thin but fairly long one. Unfortunately, zip ties have a ridge along either edge which prevents the teeth engaging with the adjuster cogs on the turntable.  I used a craft knife to cut the ridge away (quite tricky and patience-taxing!) and was left with something resembling a toothed belt. I threaded the tie into its zip lock, leaving it long enough to fit loosely over both adjuster cogs. I put one end of the loop on the motor adjuster cog, then hooked the other end over the knob adjuster cog and tightened the zip tie. I made sure to position the zip lock so it wouldn’t foul either cog. I found that putting the zip lock on the left so that when the knob is adjusted all the way ‘+’ the zip lock is just touching the plinth cutout was about right. That way, when the knob is adjusted all the way ‘-‘ the zip lock isn’t touching the knob adjuster cog. It seems to work well – it feels slightly stiff, but I seem to remember a new pitch belt feels a bit stiff as well. I stripped the motor and mechanism down then cleaned, lubricated and reassembled them, so this is probably as good as it’s going to feel for the (almost zero!) expenditure. I cinched the zip tie up so that the action was positive, but not so tight that excessive load was placed on either of the cogs. I also chose a fairly light zip tie to approximate the stiffness of a belt.

So there you have it – I imagine there are better ways of trimming the ridge off the edges of a zip tie (chisel?). I initially tried using a grinder wheel, which removed the ridge but left another one of its own! I tried a couple of craft knife blades, and found the best one for me was a rounded scalpel-like blade. I’ll leave the experimentation to you. Or maybe you’ll just buy a new pitch belt – especially if you’re not a cheapskate like me!

Thorens TD-115 and the repairer with two left hands…

I’m working on a TD-115 that belongs to friend Richard. It was pretty hammered, looked like it had been living in a shed for years. I’ve stripped it down, cleaned every contact, lubricated everything that moves and tested most of the components on the circuit boards. It’s strangely constructed, I read it described as being ‘high tech done cheap’. I don’t think it’s highly rated among Thorens enthusiasts, but I’ll finish it and get it running – why not?

The foam in the suspension ‘pods’ had rotted away, well, crystallised would be a better description. I cleaned it all out and looked for new foam inserts on ebay, but there were none that I could find. I made some today – I marked out circles on a piece of quite thick foam – my friend Mike had thought thicker (and denser) was better, and any foam was better than no foam – and cut it using a foam cutter I constructed from plywood, nichrome wire and hot-melt glue. I powered it with my DC supply – 1.2A, 2.8V produced about 100 degrees according to my multimeter’s thermocouple. Cut the foam into discs, made holes in the centres with a craft knife and reassembled the pods. Seems OK!

Here are some pictures of the shemozzle. As I’ve said about other projects, if I can do it, you can!

WP_20170630_18_22_53_Pro

WP_20170630_18_25_00_Pro (1)

Today I realised, while trying to cut replacement temple pads for my Koss TNT/77 headphones, that the wire needs to be under tension to make an even cut, so I rigged up a clothes peg spring to provide same. It’s probably unnecessarily complicated, but I feel quite proud…here are some pics:

WP_20170702_12_40_20_Pro

 

WP_20170702_12_39_33_Pro

Also added banana plugs to make hooking it up to the power supply easier. It sounds like a koto or banjo if you pluck the string!

So the next thing I did wrong…broke the bobbles off the ends of the stupid plastic speed selector linkage rods. I really don’t get the way they’ve designed this thing! I reconstructed them with JB Weld, plastic tubes from Q-tips and new bobbles from an old style of cable tie that I’d saved. I didn’t expect it to work, but it did! You can see the linkages in the picture below. Friend Mike used to work at the Thorens importer years ago and said the linkages were a popular part – “Technicians were always breaking them”. Glad it’s not just me…I suppose I should have bought replacements from ebay, and I looked, but the only two listings  which contained the parts didn’t have all the linkages, had a lot of other parts I didn’t need and would have been reasonably expensive, so I just made some new ones up. Tsk.

WP_20170710_21_37_40_Pro

I’m on the final stretch with this, but it’s a long stretch: today I spent two hours or so reassembling it. I realised there are adjuster pieces on the ends of each suspension pod, so levelled them and took the opportunity to tighten and Loctite all the nuts in the pods themselves. I got the turntable running, adjusted the speed control pots (the cutouts on the top edge of the platter are for 33rpm, the ones on the bottom edge 45rpm) but there were some grinding noises as the platter revolved. I realised the height of the bearing housing can actually be adjusted – there’s a circular spring-steel washer that sits underneath it, and the three screws holding the housing in place can be adjusted, and the spring tensions the housing against them. I used my Vernier calipers to set them to about 5mm and all the grinding stopped. I’ll Loctite the screws in place. The arm lifter doesn’t work properly, but I found that if I lifted the arm and swung it inboard of the label edge, the platter stopped. The service manual has instructions for setting the auto-stop so I’ll follow them – tomorrow!

Auto-stop set: I just undid the securing screw and moved the shutter until the arm lifted at the appropriate point in the lead-out groove. THEN…I tested continuity from the audio plugs to the cartridge pins: none in the right channel. I isolated the problem to the connector the arm wand plugs into. Oh, great: I’ll have to remove the tonearm to access it! I just unscrewed the cups the arm pivots up and down in, then removed the top cup in which the arm pivots laterally. I unsoldered the tonearm wires from the terminal board under the arm and removed the tonearm base. A screw held the shaft in place, I removed it, removed the shaft then tapped the connector out with a small drift. I soldered new wires to the connector pins, heatshrunk each connection and reassembled the connector. I’m not making this very clear, but you’ll see what I mean from the photo.

WP_20170715_19_16_59_Pro

Each pin has a small spring around it so when the arm wand is installed, the pin retracts and is held against the contact pad in the wand by spring tension. Soldering wires to the pins (they had originally been crimped) heated the pins (even though I clamped them in an alligator clip as a heat shunt), must have melted the plastic slightly and made the pins move less freely in their holes. I tried freeing them up with contact cleaner and tweezers, but with limited success. However, when I reassembled the arm there was continuity all the way from the cartridge to the ends of the tonearm wires, phew!

So, on the home stretch (I know I’ve said this before!) – acrylic cement arrived, I glued the crack in the dustcover and fitted a small aluminium plate at the rear of the cover to reinforce the repair. Did some more polishing and waxed the plinth. I found that the arm wasn’t lifting very high at the end of the side, so I shortened and reformed the spring responsible for that. Had to have another go at setting the auto-stop shutter, but finally everything is working as it should. I’ll listen to a record tomorrow, take some photos and list it. I think this has taken me about a month, off and on. Quite a project!

Abiding impressions of this turntable: ambitious, convoluted design which has been cheaply realised. Takes an absolute age to set everything up. I doubt that this could hold its own against any of the Japanese turntables of the same era and price point. Why didn’t Thorens stick to making high-end ‘tables? Actually, I take that back – the TD-280 is an underrated deck. Very simple, well-executed. THAT’S the one to buy if you’re on a budget and absolutely must have a Thorens (IMHO).

Adventures in old tech…until your mind reels…