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Is SMART Really Useful?

Being in technology for a long time, I have seen my fair share of disk failures. However I have never seen a single instance where SMART has issued a sufficient warning to backup any data on a failing disk. The following is an example of this in action.

Toshiba MQ01ABD050
Toshiba MQ01ABD050

Here is a 2.5″ Toshiba MQ01ABD050 500GB disk drive. This unit was made in 2014, but has a very low hour count of ~8 months, with only ~5 months of the heads being loaded onto the platters, since it has been used to store offline files. This disk was working perfectly the last time it was plugged in a few weeks ago, but today within seconds of starting to transfer data, it began slowing down, then stopped entirely. A quick look at the SMART stats showed over 4000 reallocated sectors, so a full scan was initiated.

SMART Test Failure
SMART Test Failure

After the couple of hours an extended test takes, the firmware managed to find a total of 16,376 bad sectors, of which 10K+ were still pending reallocation. Just after the test finished, the disk began making the usual clicking sound of the head actuator losing lock on the servo tracks. Yet SMART was still insisting that the disk was OK! In total about 3 hours between first power up & the disk failing entirely. This is possibly the most sudden failure of a disk I’ve seen so far, but SMART didn’t even twig from the huge number of sector reallocations that something was amiss. I don’t believe the platters are at fault here, it’s most likely to be either a head fault or preamp failure, as I don’t think platters can catastrophically fail this quickly. I expected SMART to at least flag that the drive was in a bad state once it’s self-test completed, but nope.

Internals
Internals

After pulling the lid on this disk, to see if there’s any evidence of a head crashing into a platter, there’s nothing – at least on a macroscopic scale, the single platter is pristine. I’ve seen disks crash to the point where the coating has been scrubbed from the platters so thoroughly that they’ve been returned to the glass discs they started off as, with the enclosure packed full of fine black powder that used to be data layer, but there’s no indication of mechanical failure here. Electronic failure is looking very likely.

Clearly, relying on SMART to alert when a disk is about to take a dive is an unwise idea, replacing drives after a set period is much better insurance if they are used for critical applications. Of course, current backups is always a good idea, no matter the age of drive.

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Panasonic NV-M5 VHS Camcorder Teardown

Overview

Panasonic NV-M5 Camera
Panasonic NV-M5 Camera

Time foe some more retro tech! This is a 1980’s vintage CCD-based VHS camcorder from Panasonic, the NV-M5. There are a lot of parts to one of these (unlike modern cameras), so I’ll split this post into several sections to make things easier to read (and easier to keep track of what I’m talking about :)).

Left Side
Left Side

The left side of the camera holds the autofocus, white balance, shutter speed & date controls.

Left Side Controls
Left Side Controls
Lens Adjustments
Lens Adjustments

The lens is fully adjustable, with either manual or motorized automatic control.

Rear Panel
Rear Panel

The back panel has the battery slot, a very strange looking DC input connector, remote control connector & the earphone jack.

Top Controls
Top Controls

The top panel of the camera holds the main power controls, manual tape tracking & the tape transport control panel.

Viewfinder
Viewfinder

The viewfinder is mounted on a swivel mount. There’s a CRT based composite monitor in here. Hack ahoy!

Camera Section

Process Board Assembly
Process Board Assembly

Here’s the camera section of the camcorder, and is totally packed with electronics! There’s at least half a dozen separate boards in here, all fitted together around the optics tube assembly.

AWB PCB
AWB PCB

On the top of the assembly is the Automatic White Balance PCB. Many adjustments here to get everything set right. Not much on the other side of this board other than a bunch of Op-Amps. The iris stepper motor is fitted in a milled opening in the PCB, this connects to one of the other PCBs in the camera module.

AWB Sensor
AWB Sensor

Here’s the AWB sensor, mounted next to the lens. I’m not all to certain how this works, but the service manual has the pinout, and there are outputs for all the colour channels, RGB. So it’s probably a trio of photodiodes with filters.

Focus & Zoom Motors
Focus & Zoom Motors

Focus & Zoom are controlled with a pair of DC gear motors. The manual operation is feasible through the use of slip clutches in the final drive pinion onto the lens barrel.

Process Board
Process Board

The main camera section process board is above. This board does all the signal processing for the CCD, has the bias voltage supplies and houses the control sections for the motorized parts of the optics assembly. There are quite a few dipped Tantalum capacitors on pigtails, instead of being directly board mounted. This was probably done due to space requirements on the PCB itself.2016-08-20_13-40-11_000357

Under the steel shield on this board is some of the main signal processing for the CCD.

Optics Assembly
Optics Assembly

The back of the optics tube is a heavy casting, to supress vibration. This will be more clear later on.

Position Sensor Flex
Position Sensor Flex

The position of the lens elements is determined by reflective strips on the barrel & sensors on this flex PCB.

Sub Process Board
Sub Process Board

There’s another small board tucked into the side of the tube, this hooks into the process PCB.

Process Delay Line
Process Delay Line

According to the schematic, there’s nothing much on this board, just a delay line & a few transistors.

Piezo Focus Disc
Piezo Focus Disc

Here’s the reason for the heavy alloy casing at the CCD mounting end of the optics: the fine focus adjustment is done with a piezoelectric disc, the entire CCD assembly is mounted to this board. Applying voltage to the electrodes moves the assembly slightly to alter the position of the CCD. The blue glass in the centre of the unit is the IR filter.

IR Relective Sensors
IR Relective Sensors

The barrel position sensors are these IR-reflective type.

Iris Assembly
Iris Assembly

The iris is mounted just before the CCD, this is controlled with a galvanometer-type device with position sensors incorporated.

Iris Opening
Iris Opening

Pushing on the operating lever with the end of my screwdriver opens the leaves of the iris against the return spring.

Tape Transport & Main Control

Main Control Board
Main Control Board

Tucked into the side of the main body of the unit is the main system control board. This PCB houses all the vital functions of the camera: Power Supply, Servo Control, Colour Control,Video Amplifiers, etc.

Tape Drum
Tape Drum

Here’s the main tape transport mechanism, this is made of steel & aluminium stampings for structural support. The drum used in this transport is noticeably smaller than a standard VHS drum, the tape is wrapped around more of the drum surface to compensate.

Tape Transport
Tape Transport

The VHS tape sits in this carriage & the spools drive the supply & take up reels in the cartridge.

Main Control PCB
Main Control PCB

Here’s the component side of the main control PCB. This one is very densely packed with parts, I wouldn’t like to try & troubleshoot something like this!

Main PCB Left
Main PCB Left

The left side has the video head amp at the top, a Panasonic AN3311K 4-head video amp. Below that is video processing, the blue components are the analogue delay lines. There are a couple of hybrid flat-flex PCBs tucked in between with a couple of ICs & many passives. These hybrids handle the luma & chroma signals.
Top left is the capstan motor driver a Rohm BA6430S. The transport motors are all 3-phase brushless, with exception of the loading motor, which is a brushed DC type.

Delay Line
Delay Line

Here’s what is inside the delay lines for the analogue video circuits. The plastic casing holds a felt liner, inside which is the delay line itself.

Internal Glass
Internal Glass

The delay is created by sending an acoustic signal through the quartz crystal inside the device by a piezoelectric transducer, bouncing it off the walls of the crystal before returning it to a similar transducer.

Main PCB Centre
Main PCB Centre

Here’s the centre of the board, the strange crystal at bottom centre is the clock crystal for the head drum servo. Why it has 3 pins I’m not sure, only the two pins to the crystal inside are shown connected on the schematic. Maybe grounding the case?
The main servo controls for the head drum & the capstan motor are top centre, these get a control signal from the tape to lock the speed of the relative components.

Main PCB Right
Main PCB Right

Here’s the right hand side. The main power supply circuitry is at top right, with a large can containing 4 switching inductors & a ferrite pot core transformer. All these converters are controlled by a single BA6149 6-channel DC-DC converter controller IC via a ULN2003 transistor array.
The ceramic hybrid board next to the PSU has 7 switch transistors for driving various indicator LEDs.
The large tabbed IC bottom centre is the loading motor drive, an IC from Mitsubishi, the M54543. This has bidirectional DC control of the motor & built in braking functions. The large quad flat pack IC on the right is the MN1237A on-screen character generator, with the two clock crystals for the main microcontroller.

Erase Head
Erase Head

The full erase head has it’s power supply & oscillator on board, applying 9v to this board results in an AC signal to the head, which erases the old recording from the tape before the new recording is laid down by the flying heads on the drum.

Audio Control PCB
Audio Control PCB

The Audio & Control head is connected to this PCB, which handles both reading back audio from the tape & recording new audio tracks. The audio bias oscillator is on this board, & the onboard microphone feeds it’s signal here. The control head is fed directly through to the servo section of the main board.

Drum Motor
Drum Motor

The motor that drives the head drum is another DC brushless 3-phase type.

Hall Sensors
Hall Sensors

These 3 Hall sensors are used by the motor drive to determine the rotor position & time commutation accordingly.

Stator
Stator

The stator on this motor is of interesting construction, with no laminated core, the coils are moulded into the plastic holder. The tach sensor is on the side of the stator core. This senses a small magnet on the outside of the rotor to determine rotational speed. For PAL recordings, the drum rotates at 1500 RPM.

Motor Removed
Motor Removed

Not much under the stator other than the bearing housing & the feedthrough to the rotary transformer.

Head Disc
Head Disc

The heads are mounted onto the top disc of the drum, 4 heads in this recorder. The signals are transmitted to the rotating section through the ferrite rotary transformer on the bottom section.

Head Chip
Head Chip

The tiny winding of the ferrite video head can just about be seen on the end of the brass mounting.

Capstan Motor Components
Capstan Motor Components

The capstan motor is similar to the drum motor, only this one is flat. The rotor has a ferrite magnet, in this case it wasn’t glued in place, just held by it’s magnetic field.

Capstan Motor Stator
Capstan Motor Stator

The PCB on this motor has a steel backing to complete the magnetic circuit, the coils for the 3 motor phases are simply glued in place. The Hall sensors on this motor are placed in the middle of the windings though.
Again there is a tach sensor on the edge of the board that communicates the speed back to the controller. This allows the servo to remain locked at constant speed.

Viewfinder

Viewfinder Assembly
Viewfinder Assembly

As usual with these cameras, this section is the CRT based viewfinder. These units take the composite signal from the camera to display the scene. This one has many more pins than the usual viewfinder. I’ll hack a manual input into this, but I’ll leave that for another post.

Viewfinder Circuits
Viewfinder Circuits

Being an older camera than the ones I’ve had before, this one is on a pair of PCBs, which are both single-sided.

Main Viewfinder Board
Main Viewfinder Board

The main board has all the power components for driving the CRT & some of the adjustments. The main HV flyback transformer is on the right. This part creates both the final anode voltage for the tube & the focus/grid voltages.

Viewfinder Control PCB Top
Viewfinder Control PCB Top

The viewfinder control IC is on a separate daughter board in this camera, with two more controls.

Control IC
Control IC

The control IC is a Matsushita AN2510S, this has all the logic required to separate the sync pulses from the composite signal & generate an image on the CRT.

Viewfinder CRT Frame
Viewfinder CRT Frame

The recording indicator LEDs are mounted in the frame of the CRT & appear above the image in the viewfinder.

Viewfinder CRT With Yoke
Viewfinder CRT With Yoke

Here the CRT has been separated from the rest of the circuitry with just the deflection yoke still attached.

M01JPG5WB CRT
M01JPG5WB CRT

The electron gun in this viewfinder CRT is massive in comparison to the others that I have seen, and the neck of the tube is also much wider. These old tubes were very well manufactured.

Viewfinder Optics
Viewfinder Optics

A simple mirror & magnifying lens completes the viewfinder unit.

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HPI Savage X 4.6 LiPo Receiver Battery

3S Lithium-Polymer Pack
3S Lithium-Polymer Pack

To provide more run time with the conversion to petrol & spark ignition, I have also upgraded the on-board electronics supply to compensate for the extra ~650mA draw of the ignition module.
This modification is centred around a 3S Lithium-Polymer battery pack, providing a nominal 11.1v to a voltage regulator, which steps down this higher voltage to the ~6v required by the receiver & servo electronics.

Power Regulator
Power Regulator
Power Regulator
Power Regulator

The regulator, shown above, is a Texas Instruments PTN78060WAZ wide-input voltage adjustable regulator. This module has an exceptionally high efficiency of ~96% at it’s full output current of 3A. The output voltage is set by a precision resistor, soldered to the back of the module, in this case 6.5v. Standard RC connectors are used on the regulator to allow connection between the power switch & the radio receiver.

Receiver Box
Receiver Box

Everything tucked away into place inside the receiver box. The 3S 1000mAh LiPo fits perfectly in the space where the original Ni-Mh hump pack was located.
The completely stable output voltage of the regulator over the discharge curve of the new battery gives a much more stable supply to the radio & ignition, so I should experience fewer dropouts. Plus the fact that the engine now relies on power from the receiver pack to run, it’s a built in fail safe – if the power dies to the receiver, the engine also cuts out.

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HP Photosmart 375

Top
Top

This is a HP PhotoSmart 375 portable photo printer. With built in card reader, screen & PictBridge.
Top of the printer showing the UI Buttons & Screen.

Front
Front

Front of the unit, card reader slots at the top, Pictbridge USB connector at top left. Paper out slot at bottom. Cartridge door is on the right.

Cartridge Door
Cartridge Door

Here the cartridge door is open. Takes HP 95 Tri-Colour Inkjet Cartridge.

Battery Compartment
Battery Compartment

Battery compartment on the bottom of the unit. A Li-Ion battery pack can be installed here for mobile photo printing.

Bottom Label
Bottom Label

Specifications label.

USB + Power
USB + Power

Power adaptor & USB connection for PC use.

Paper Tray
Paper Tray

Rear door opened. Showing the paper feed tray.

Paper Feeder
Paper Feeder

Rear door has been removed in this shot. Paper feed roller & platen roller can be seen here.

Rear Cover Paper Feeder
Rear Cover Paper Feeder

Paper holder attached to rear door.

Top Cover
Top Cover

Bottom of the top cover, with connections for the buttons & LCD panel.

Main PCB
Main PCB

This is the main PCB of the unit. Controls all aspects of the printer. CPU in center, card reader sockets are along bottom edge. various support circuitry surrounds the CPU.

Rear
Rear

Rear shell has been removed here. Showing the main frame & the carriage drive motor on the left.

Carriage Drive
Carriage Drive

Closeup of the carriage drive motor & timing belt system. All the motors in this printer are DC servo motors, not steppers.

Main Drive Motor
Main Drive Motor

Main drive motor, feeds paper, drives rollers, operates cleaning mechanism for the inkjets.

Shaft Encoder
Shaft Encoder

Mainshaft encoder. Main drive motor is bottom right hand side with timing belt drive.

CPU
CPU

Closeup of the CPU. This is a Phillips ARM chip, unknown spec.

Card Reader Sockets
Card Reader Sockets

Detail of the card reader sockets, this unit takes all current types of Flash memory card.

HP 95 Tri-color Inkjet Print Cartridge