Arduino 1.6.x compiler options...

I'd noticed recently that since I'd upgraded the Arduino IDE to 1.6.x, some programs compiled and were smaller than they used to be. Great!

... the also don't run so fast... not so great.

After some googling around, the compiler options for optimisation had been changed.

So if you need something to compile and run quickly, you can.

Here's how to change it...

Navigate your way to the default Arduino directory in program files, and locate the platform.txt file

On my windows box, it's at C:\Program Files (x86)\Arduino\hardware\arduino\avr
On my Ubuntu box it's Home\Downloads\arduino-1.6.12\hardware\arduino\avr  (Why did I ./install.sh from the downloads folder!!!)

there's also one in the \hardware directory itself. That's not it!

Mine looks like this :

# Arduino AVR Core and platform. # ------------------------------ # # For more info: # https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5-3rd-party-Hardware-specification name=Arduino AVR Boards version=1.6.14 # AVR compile variables # --------------------- compiler.warning_flags=-w compiler.warning_flags.none=-w compiler.warning_flags.default= compiler.warning_flags.more=-Wall compiler.warning_flags.all=-Wall -Wextra # Default "compiler.path" is correct, change only if you want to override the initial value compiler.path={runtime.tools.avr-gcc.path}/bin/ compiler.c.cmd=avr-gcc compiler.c.flags=-c -g -Os {compiler.warning_flags} -std=gnu11 -ffunction-sections -fdata-sections -MMD -flto -fno-fat-lto-objects compiler.c.elf.flags={compiler.warning_flags} -Os -flto -fuse-linker-plugin -Wl,--gc-sections compiler.c.elf.cmd=avr-gcc compiler.S.flags=-c -g -x assembler-with-cpp -flto compiler.cpp.cmd=avr-g++ compiler.cpp.flags=-c -g -Os {compiler.warning_flags} -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -MMD -flto compiler.ar.cmd=avr-gcc-ar compiler.ar.flags=rcs compiler.objcopy.cmd=avr-objcopy compiler.objcopy.eep.flags=-O ihex -j .eeprom --set-section-flags=.eeprom=alloc,load --no-change-warnings --change-section-lma .eeprom=0 compiler.elf2hex.flags=-O ihex -R .eeprom compiler.elf2hex.cmd=avr-objcopy compiler.ldflags= compiler.size.cmd=avr-size # This can be overridden in boards.txt build.extra_flags= # These can be overridden in platform.local.txt compiler.c.extra_flags= compiler.c.elf.extra_flags= compiler.S.extra_flags= compiler.cpp.extra_flags= compiler.ar.extra_flags= compiler.objcopy.eep.extra_flags= compiler.elf2hex.extra_flags= # AVR compile patterns # -------------------- ## Compile c files recipe.c.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.c.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.c.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}" ## Compile c++ files recipe.cpp.o.pattern="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.cpp.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}" ## Compile S files recipe.S.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.S.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.S.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}" ## Create archives # archive_file_path is needed for backwards compatibility with IDE 1.6.5 or older, IDE 1.6.6 or newer overrides this value archive_file_path={build.path}/{archive_file} recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} {compiler.ar.extra_flags} "{archive_file_path}" "{object_file}" ## Combine gc-sections, archives, and objects recipe.c.combine.pattern="{compiler.path}{compiler.c.elf.cmd}" {compiler.c.elf.flags} -mmcu={build.mcu} {compiler.c.elf.extra_flags} -o "{build.path}/{build.project_name}.elf" {object_files} "{build.path}/{archive_file}" "-L{build.path}" -lm ## Create output files (.eep and .hex) recipe.objcopy.eep.pattern="{compiler.path}{compiler.objcopy.cmd}" {compiler.objcopy.eep.flags} {compiler.objcopy.eep.extra_flags} "{build.path}/{build.project_name}.elf" "{build.path}/{build.project_name}.eep" recipe.objcopy.hex.pattern="{compiler.path}{compiler.elf2hex.cmd}" {compiler.elf2hex.flags} {compiler.elf2hex.extra_flags} "{build.path}/{build.project_name}.elf" "{build.path}/{build.project_name}.hex" ## Save hex recipe.output.tmp_file={build.project_name}.hex recipe.output.save_file={build.project_name}.{build.variant}.hex ## Compute size recipe.size.pattern="{compiler.path}{compiler.size.cmd}" -A "{build.path}/{build.project_name}.elf" recipe.size.regex=^(?:\.text|\.data|\.bootloader)\s+([0-9]+).* recipe.size.regex.data=^(?:\.data|\.bss|\.noinit)\s+([0-9]+).* recipe.size.regex.eeprom=^(?:\.eeprom)\s+([0-9]+).* ## Preprocessor preproc.includes.flags=-w -x c++ -M -MG -MP recipe.preproc.includes="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} {preproc.includes.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.cpp.extra_flags} {build.extra_flags} {includes} "{source_file}" preproc.macros.flags=-w -x c++ -E -CC recipe.preproc.macros="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} {preproc.macros.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.cpp.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{preprocessed_file_path}" # AVR Uploader/Programmers tools # ------------------------------ tools.avrdude.path={runtime.tools.avrdude.path} tools.avrdude.cmd.path={path}/bin/avrdude tools.avrdude.config.path={path}/etc/avrdude.conf tools.avrdude.upload.params.verbose=-v tools.avrdude.upload.params.quiet=-q -q tools.avrdude.upload.params.noverify=-V tools.avrdude.upload.pattern="{cmd.path}" "-C{config.path}" {upload.verbose} {upload.verify} -p{build.mcu} -c{upload.protocol} -P{serial.port} -b{upload.speed} -D "-Uflash:w:{build.path}/{build.project_name}.hex:i" tools.avrdude.program.params.verbose=-v tools.avrdude.program.params.quiet=-q -q tools.avrdude.program.params.noverify=-V tools.avrdude.program.pattern="{cmd.path}" "-C{config.path}" {program.verbose} {program.verify} -p{build.mcu} -c{protocol} {program.extra_params} "-Uflash:w:{build.path}/{build.project_name}.hex:i" tools.avrdude.erase.params.verbose=-v tools.avrdude.erase.params.quiet=-q -q tools.avrdude.erase.pattern="{cmd.path}" "-C{config.path}" {erase.verbose} -p{build.mcu} -c{protocol} {program.extra_params} -e -Ulock:w:{bootloader.unlock_bits}:m -Uefuse:w:{bootloader.extended_fuses}:m -Uhfuse:w:{bootloader.high_fuses}:m -Ulfuse:w:{bootloader.low_fuses}:m tools.avrdude.bootloader.params.verbose=-v tools.avrdude.bootloader.params.quiet=-q -q tools.avrdude.bootloader.pattern="{cmd.path}" "-C{config.path}" {bootloader.verbose} -p{build.mcu} -c{protocol} {program.extra_params} "-Uflash:w:{runtime.platform.path}/bootloaders/{bootloader.file}:i" -Ulock:w:{bootloader.lock_bits}:m tools.avrdude_remote.upload.pattern=/usr/bin/run-avrdude /tmp/sketch.hex {upload.verbose} -p{build.mcu} # USB Default Flags # Default blank usb manufacturer will be filled in at compile time # - from numeric vendor ID, set to Unknown otherwise build.usb_manufacturer="Unknown" build.usb_flags=-DUSB_VID={build.vid} -DUSB_PID={build.pid} '-DUSB_MANUFACTURER={build.usb_manufacturer}' '-DUSB_PRODUCT={build.usb_product}'

Now I'd rename this to platform.old, so it's there if we screw it up, or wish to revert to slower, but more space-efficient code.

Now, open this file in your favorite text editor (mine's Notepad++ on windows) and do a find and replace on all instances of -Os (that's the letter O) and replace it with -O2 (again, the letter O) There are 3 instances of it in my file...

Bingo, save that as platform.txt in the directory, and you're done.

Here's my modified file...

# Arduino AVR Core and platform. # ------------------------------ # # For more info: # https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5-3rd-party-Hardware-specification name=Arduino AVR Boards version=1.6.14 # AVR compile variables # --------------------- compiler.warning_flags=-w compiler.warning_flags.none=-w compiler.warning_flags.default= compiler.warning_flags.more=-Wall compiler.warning_flags.all=-Wall -Wextra # Default "compiler.path" is correct, change only if you want to override the initial value compiler.path={runtime.tools.avr-gcc.path}/bin/ compiler.c.cmd=avr-gcc compiler.c.flags=-c -g -O2 {compiler.warning_flags} -std=gnu11 -ffunction-sections -fdata-sections -MMD -flto -fno-fat-lto-objects compiler.c.elf.flags={compiler.warning_flags} -O2 -flto -fuse-linker-plugin -Wl,--gc-sections compiler.c.elf.cmd=avr-gcc compiler.S.flags=-c -g -x assembler-with-cpp -flto compiler.cpp.cmd=avr-g++ compiler.cpp.flags=-c -g -O2 {compiler.warning_flags} -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -MMD -flto compiler.ar.cmd=avr-gcc-ar compiler.ar.flags=rcs compiler.objcopy.cmd=avr-objcopy compiler.objcopy.eep.flags=-O ihex -j .eeprom --set-section-flags=.eeprom=alloc,load --no-change-warnings --change-section-lma .eeprom=0 compiler.elf2hex.flags=-O ihex -R .eeprom compiler.elf2hex.cmd=avr-objcopy compiler.ldflags= compiler.size.cmd=avr-size # This can be overridden in boards.txt build.extra_flags= # These can be overridden in platform.local.txt compiler.c.extra_flags= compiler.c.elf.extra_flags= compiler.S.extra_flags= compiler.cpp.extra_flags= compiler.ar.extra_flags= compiler.objcopy.eep.extra_flags= compiler.elf2hex.extra_flags= # AVR compile patterns # -------------------- ## Compile c files recipe.c.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.c.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.c.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}" ## Compile c++ files recipe.cpp.o.pattern="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.cpp.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}" ## Compile S files recipe.S.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.S.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.S.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}" ## Create archives # archive_file_path is needed for backwards compatibility with IDE 1.6.5 or older, IDE 1.6.6 or newer overrides this value archive_file_path={build.path}/{archive_file} recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} {compiler.ar.extra_flags} "{archive_file_path}" "{object_file}" ## Combine gc-sections, archives, and objects recipe.c.combine.pattern="{compiler.path}{compiler.c.elf.cmd}" {compiler.c.elf.flags} -mmcu={build.mcu} {compiler.c.elf.extra_flags} -o "{build.path}/{build.project_name}.elf" {object_files} "{build.path}/{archive_file}" "-L{build.path}" -lm ## Create output files (.eep and .hex) recipe.objcopy.eep.pattern="{compiler.path}{compiler.objcopy.cmd}" {compiler.objcopy.eep.flags} {compiler.objcopy.eep.extra_flags} "{build.path}/{build.project_name}.elf" "{build.path}/{build.project_name}.eep" recipe.objcopy.hex.pattern="{compiler.path}{compiler.elf2hex.cmd}" {compiler.elf2hex.flags} {compiler.elf2hex.extra_flags} "{build.path}/{build.project_name}.elf" "{build.path}/{build.project_name}.hex" ## Save hex recipe.output.tmp_file={build.project_name}.hex recipe.output.save_file={build.project_name}.{build.variant}.hex ## Compute size recipe.size.pattern="{compiler.path}{compiler.size.cmd}" -A "{build.path}/{build.project_name}.elf" recipe.size.regex=^(?:\.text|\.data|\.bootloader)\s+([0-9]+).* recipe.size.regex.data=^(?:\.data|\.bss|\.noinit)\s+([0-9]+).* recipe.size.regex.eeprom=^(?:\.eeprom)\s+([0-9]+).* ## Preprocessor preproc.includes.flags=-w -x c++ -M -MG -MP recipe.preproc.includes="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} {preproc.includes.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.cpp.extra_flags} {build.extra_flags} {includes} "{source_file}" preproc.macros.flags=-w -x c++ -E -CC recipe.preproc.macros="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} {preproc.macros.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.cpp.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{preprocessed_file_path}" # AVR Uploader/Programmers tools # ------------------------------ tools.avrdude.path={runtime.tools.avrdude.path} tools.avrdude.cmd.path={path}/bin/avrdude tools.avrdude.config.path={path}/etc/avrdude.conf tools.avrdude.upload.params.verbose=-v tools.avrdude.upload.params.quiet=-q -q tools.avrdude.upload.params.noverify=-V tools.avrdude.upload.pattern="{cmd.path}" "-C{config.path}" {upload.verbose} {upload.verify} -p{build.mcu} -c{upload.protocol} -P{serial.port} -b{upload.speed} -D "-Uflash:w:{build.path}/{build.project_name}.hex:i" tools.avrdude.program.params.verbose=-v tools.avrdude.program.params.quiet=-q -q tools.avrdude.program.params.noverify=-V tools.avrdude.program.pattern="{cmd.path}" "-C{config.path}" {program.verbose} {program.verify} -p{build.mcu} -c{protocol} {program.extra_params} "-Uflash:w:{build.path}/{build.project_name}.hex:i" tools.avrdude.erase.params.verbose=-v tools.avrdude.erase.params.quiet=-q -q tools.avrdude.erase.pattern="{cmd.path}" "-C{config.path}" {erase.verbose} -p{build.mcu} -c{protocol} {program.extra_params} -e -Ulock:w:{bootloader.unlock_bits}:m -Uefuse:w:{bootloader.extended_fuses}:m -Uhfuse:w:{bootloader.high_fuses}:m -Ulfuse:w:{bootloader.low_fuses}:m tools.avrdude.bootloader.params.verbose=-v tools.avrdude.bootloader.params.quiet=-q -q tools.avrdude.bootloader.pattern="{cmd.path}" "-C{config.path}" {bootloader.verbose} -p{build.mcu} -c{protocol} {program.extra_params} "-Uflash:w:{runtime.platform.path}/bootloaders/{bootloader.file}:i" -Ulock:w:{bootloader.lock_bits}:m tools.avrdude_remote.upload.pattern=/usr/bin/run-avrdude /tmp/sketch.hex {upload.verbose} -p{build.mcu} # USB Default Flags # Default blank usb manufacturer will be filled in at compile time # - from numeric vendor ID, set to Unknown otherwise build.usb_manufacturer="Unknown" build.usb_flags=-DUSB_VID={build.vid} -DUSB_PID={build.pid} '-DUSB_MANUFACTURER={build.usb_manufacturer}' '-DUSB_PRODUCT={build.usb_product}'

You can now enjoy faster, but fatter sketches!

.. or not!

NAD 5425 CD player - no display

Just a quick one. This delightful NAD 5425 CD player.

Arrived skipping / not reading discs and no display.


Skipping and intermittently not reading discs was an easy fix, a quick clean up of the optics with an airduster, and very careful cleaning of the lens (DON'T USE IPA HERE! - it can damage the optical coating on the lens. It's easy just to breathe on it, and give it a gentle wipe with something lint-free). That had it playing even the most mangy looking disc!




No display?



Let investigate...

The main board is removed ....









.. and the display cowl removed (there's a couple of screws underneath, and a plastic clip.)












... and an open-circuit incandescent lamp is the culprit...










To improve reliability, and LED and 1K limiting resistor is fixed in place. Note the capton tape to insulate it electrically from the links on the board below. Anode (+ve) is to the right in this picture.

The LED I chose was a wide-angle, warm white LED, which I hope will match the original incandescent lamp closely.







... which is does nicely!














I've not tried these wide-angle LEDs before. They're quite good. These are both warm white examples, although they differ in colour slightly! You can clearly see the focussed "beam" coming from the right hand LED, and the much more diffuse spread of light from the left hand "wide-angle" LED.





Job done. Another saved from landfill!

Leak 2100 amplifier repairs.

A while back, David (from the motherland) donated some stuff to the cause.

This Leak amplifier was amongst the things he dropped off...

Dating from around 1974, and mostly valueless... eBay prices these at about £30 at the time of writing.

Still, there's no point in it just sitting in a pile...






It's been through the wars a bit, but that's OK. I need something to practise my veneering skills on, for a forthcoming turntable project, so this may do as a test bed...










Typical 70's construction.

I'd labelled the amp up "Hums" ....










There's something unpleasant oozing out of the top of the positive rail smoothing cap... It's a 6,800uF 40V part....










... I have some 10,000uF 63V parts, which are slightly fatter, but much shorter. The fit in the clips OK, so they'll do....

Powering up instantly blows both 5A fuses on the main board. You can see in the photo, I've lifted R3 and R5 on the small vertical PCB. This is the protection board. It's purpose in life is to blow fuses by shorting out the supply rails with a triac in the event of there being more that 0.5VDC on the speaker outputs. A sort of crowbar circuit.

Powering up again, with new fuses and checking the speaker outputs (with no speakers attached) for DC shows everything in order.

R3 and R5 are soldered back into position and power is applied again. All is well. I wonder if one rail came up before the other due to the new/larger caps?

I check round the caps on the main board for ESR. Remarkably, they all check out OK. Every last one of them! I even checked the calibration on the ESR meter because I doubted it!


The power indicator lamp on the front doesn't work, because, well... it's missing. I'll make up some white LED's to go in...











I had a short length of LED strip left over from when I fitted some lighting in my kitchen, so I cut off a short length. The voltage supply for the lamps is half wave rectified, with no smoothing. It peaks at around 20 volts, so I added a 470 ohm resistor to limit the current a bit, and added 100uF to smooth the supply a bit, so the LED's don't flicker.




I removed the original lamp holder, and fixed the strip in place with a spot of hot-melt.

Looks good....








After a prolonged test in the workshop, the amp remains well-mannered, and sounds decent. It's quiet and produces around 30 watts into 8 ohms. I'm actually quite taken with it, so much so, I'm going to put it in the main hifi set up for a bit.. one issue though... the input sensitivity. It's a tiny 140mV for line inputs. We'll need to fit an attenuator on the input I intend to use for the CD player. Thankfully there's an attenuator switch fitted to the Tuner input, which is switched on the back for two different levels. Looking at the circuit, my calculations show it'll do as it stands. Good news!

Now to make up some 5-pin DIN to RCA leads, and order some veneer!

Talking of 5-pin DIN plugs... this Leak doesn't quite follow convention....


1 is Right input
2 is GND
3 is Left input.


4 is Right output for Tape/cassette
5 is Left output for Tape/cassette....

Wharfdale Airedale SP2 Speakers.

Well, there appears to scant information on the web about these wonderful speakers, so I thought I'd share some pictures of mine up. Sadly they're not going to be with me long, as they're not exactly wife-friendly, due to there huge size (H 88cm W 46.5cm D 44cm!)

They were Wharfdale's top-of-the-range speakers in the mid 70's.

Tweeter. I saw a thread on a forum that said these were ribbon tweeters, but I don't think so. How do you make a round ribbon?

Upper mid-range, with felt suspension...

4" mid-range, again with felt suspension.












... and the 10" bass driver, with rubber suspension.

They sound fantastic, and are in really good condition. Speakers of this age generally start to have problems with the suspension breaking up, but these are just great. Sadly they're just too big...so it's off to eBay with them :(

Quad 405-2 Amplifier - restoration.

The next part of the Quad series. The mighty 405-2 power amplifier. Famed for it's current dumping design.

This amplifier was made around 1984, as some of the RCA transistors are nicely dated.

This amplifier isn't performing too well. It's distorting, and humming slightly.
















The amplifier is nicely laid out, although I'm not too impressed with the safety earthing arrangements. The earth is taken to a point a long way from where the supply is grounded. This can exacerbate ground loop issues. This amp hums, and I also have a friend whose 405 hums quite badly. Could this be the cause?





The ground connections to the speakers are also made separately...










Removal of each amplifier board is made easy by removing the two rubber bungs thoughtfully supplied by Quad, which allow insertion of a long screwdriver to gain access to the lower screws securing each board to the large heatsink at the front. The boards fitted to this amplifier are rev. 7 boards, and are also fitted with voltage limiters, so It's suitable for driving Quad's ESL speakers.







First inspection of the amplifier show some of the Red cased electrolytic capacitors are showing signs of age, looking a bit "sweaty" and having cracked cases.

Two of the caps in my amp (C17 & C2) are bi-polar, which is a pain. C2 can be replaced by a conventional electrolytic, with the positive side to ground, but C17 must remain bi-polar... which is a pain , because they're awful and I don't stock any!









Low-and-behold, C5, a 6.3V Electrolytic is leaking and has turned the pin green!

Both of the large 10,000uF capacitors test like new, so they can stay.
















I decided, in an effort to mitigate any ground-loop issues, to ground the speakers and the mains safety earth back to the same point.








So after a blanket change of the capacitors, the amplifier powers up, and tests very well, with no adverse behaviour, and there's certainly no perceivable hum! All the unpleasant distortion has gone :)

There are quite a few websites detailing modifications to this amplifier, in particular Keith Snook's site (here), I did think about implementing some of these modifications, but I'm rather taken with it in stock form, so it will stay like that!

Guilty as changed, your honour ! (There's a joke in there!)

The Nikon D3100 camera disaster, a thank you, and a recommendation.

Back when the weather was fine, I was out in the garden taking some nice photos at a barbecue party. All was well until I dropped my beloved Nikon D3100 camera onto concrete.... The lens developed a bit of lateral play in the zoom, but it was still working OK....

... until it stopped auto-focusing a couple of weeks later ...

Nothing to it, but to investigate.

I proved the lens was at fault by borrowing another lens from a friend. The camera body was fine...

So I stripped the lens down... sadly I don't have any pictures.

There was a bush missing, which was causing the play, so I fabricated a new one and fitted it. Lateral play issue resolved.

I managed to find the old bush, in two parts, jammed up against the primary lens cover.

 Auto focus was still not working... damn.

At this point I decided to get another lens.

Whilst looking on eBay, I spotted a replacement lens. The description was perfect, but it showed pictures of a Cannon lens. I emailed the seller, who replied, thanking me for spotting the error, and they had corrected the listing. By this stage I had purchased another lens from another dealer.

The box arrived after a few days wait..... Now I'd done a bit of research on the lens before I hit the buy button. Nikon's website informed me the lens was compatible "with all DX cameras"... and mine's a DX camera....

... what they didn't say was the auto-focus wasn't compatible with all DX cameras (well, they do, but you've really got to go looking for the information!)... boo. I needed an AF-S lens, and the new one was AF-P.

I emailed the dealer that had originally listed the correct lens wrongly on eBay (the Canon one) asking if they'd part-ex my new, but incorrect lens for the right one.

They emailed back straight away, and said they'd be happy to swap it for me anyway (despite the fact I never bought it from them!) Now that's service. I suppose I could have sent the wrong lens back, but that would have been hassle....

As a deal wasn't done on eBay, I can't even leave them positive feedback....

So thank you eBay seller alldigital0869. (Shop is called The Photographers Bag link here.) You're the best.

The two recommendations are :

1) Don't drop your camera.
2) Use alldigital0869 on eBay with complete confidence!

There's some posts in the pipe-line with photo's taken with my old Samsung camera, but, rest-assured the Nikon is back!