1989 Jaguar XJS V12 Odometer Repair

· daryl

The odometer stopped working in my XJS so I took apart the instrument cluster to investigate futher. It’s an electromechanical system that starts with a VR sensor mounted to the rear differential before being signal proccessed into something that can turn a motor and the odometer gears.

Using a bench top power supply and signal generator I managed to revive the driving motor but it was intermittent and jerky in operation. I’m not sure what type of motor it is but I flushed it with electrical switch cleaner and this improved things.

The circuit board has been discussed on other forums as it’s a similar design to the rev counter. Its a metal/ceramic substrate with thick film resistors and a mixture of surface mount and through hole mount components which I thought impressive for 1989.
The IC’s are a HEF4024B 7-stage binary counter and a TI MIC2/2 which is a custom part equivalent to a SAK215 pulse shaper IC. Other components on the board are various smt transistors including 4 of them arranged in a H-bridge configuration for driving the motor.

Here are some interesting links that discuss the speedo/odometer circuit and the similarities with the rev counter.

https://forums.jag-lovers.com/t/tachometer-rebuild/386257/12
https://forums.jag-lovers.com/t/newcomer-xjs-v12-1988-and-some-problems-start-but-no-crank/395748/73

Henry HVC200 Vacuum Cleaner Repair

· daryl

Having moved house recently I accquired an old Henry vacuum cleaner that had been used for workshop and garage duties so was rather filthy but cleaned up well with soap & water.
However it was in a questionable electrical condition with a broken plug, missing cable strain relief and worst of all, an exploaded mains filter/RFI capacitor of the Rifa brand.

Remove a couple of covers and the electrical connections are revealed. The socket on the left is a passthrough for other domestic tools I think. In the middle is the failed Rifa capacitor and mains cable missing strain relief.

You can see the capacitor casing cracked wide open and there was burn marks/staining on the surrounding plastic. I bet this made quite an unpleasant smell when it went.

Old and new capacitors. The replacement is a modern Rifa capacitor. You can also see a 1 Meg Ohm bleed resistor attached to the old capacitor, I didn’t bother salvaging this and fitted a new one instead.

New capacitor soldered to the original terminals.

Fitted in position and you can also see the outer insulation of the mains cable correctly clamped.

Here it is cleaned up and fitted with a modern ‘turbo’ brush head, this uses the suction to also drive a brush head for a more thorough cleaning on thick carpet.

During my research I discovered this model was significantly older than I thought, being made during the mid 1980’s https://numatic.fandom.com/wiki/Henry#Henry_HVC200_(1983-1987)

Here is to another 30 years service!

TRW EBC 430 ABS Reverse Engineering – Part 1 PCB

· daryl

I have given myself the project of reverse engineering a TRW EBC 430 ABS unit, typically used in early 2000’s Vauxhall or GM cars.

I believe they were designed by Kelsey-Hayes and produced by TRW given the numerous ABS related patents granted to Kelsey.

  1. Primary microcontroller – AN87C196LA which is a 16-bit Intel 80C196 variant.
  2. Secondary microcontroller – T83C51RB2 which is an 8-bit Intel 80C51 variant made by Atmel.
  3. Atmel U6809B – Failsafe IC with relay and lamp driving circuitry.
  4. ST 37041 90T316 – Judging by the surrounding components I think this is a VR sensor conditioning chip for the 4 ABS wheel speed sensors.
  5. Temic 9344.1M – Purpose unknown so far. Temic was a German semicon manufacturer who developed various automotive control modules.
  6. ST M24C01 – Serial I2C EEPROM connected to the primary MCU.
  7. Infineon 2N06L64 & 2N06L23 – N-Channel MOSFETs for driving the ABS valve solenoids.
  8. Fairchild HUF75344 – N-Channel power MOSFET for driving the ABS pump motor.
  9. Collection of diodes, resistors & capacitors – These are for filtering the VR sensor signals before processing by #4.
  10. ST L4949ED – Low drop voltage regulator for 5V output.

I’m working on a KiCad schematic for the above PCB but it’s slow going as this is a multi layer board with a solid copper ground plane on the back so it’s difficult to follow where some signals go after vias.

TPS-4000 Replacement Parts

· daryl

The new parts arrived to repair the Topward TPS-4000 power supply I had diagnosed in a previous post.

The Motorola MJ2955 was replaced with a MOSPEC branded part as originals are in short supply and popular with audio amplifier enthusiasts.

The 2SA1015GR was replaced with a BC557C as I have many of these.

Being the inquisitive type, I decided to cut open the old power transistor to see what was inside.

Using a digital microscope I managed to capture significant damage on the silicon.

Completed power supply.

Topward TPS-4000 Power Supply Repair

· daryl

The Topward TPS-4000 is a linear bench power supply with two independent adjustable outputs and a third fixed 5V output. It is this 5V output that has failed.

Original schematic (incorrect)

The original schematic seems to be missing the pass transistor and has the other transistors connected in an odd manner which suggested something might not be right.

Reverse engineered schematic (correct)

The transformer/bridge rectifier/filter capacitors have omitted for clarity.

LTspice Simulation

Q2, BD912, would have originally been a 2SA699 transistor.

Failed components – Motorola MJ2955 pass transistor and 2SA1015 sense transistor.

The MJ2955 has a short circuit between the collector & emitter and the 2SA1015 has some odd junction behavior when tested under forward & reverse bias.

I’m waiting for a replacement MJ2955 and the 2SA1015 will be replaced with whatever jellybean transistor I have at hand.

New components and completion

· daryl

The following pictures show the new components and the completed board.

Capacitors

The above image shows the new and old Rifa capacitor. You can see the crazing and discolouring on the left hand side.

TRIAC

There was some difficulty in finding an alternative TRIAC. From the part numbers on the package, TAG D2 450 800 , I took a guess on the typical specifications as I could not find a vintage TAG Semiconductors parts catalogue. I used a ST BTA16-800CW with a blocking voltage of 800V and an RMS current of 16A.

Finished PCB

The motor is now working well unloaded and is surprisingly loud at max speed (28,000 rpm).

Watch this space for a reverse engineered circuit diagram.

PCB Cleaning

· daryl

The following components were removed after inspection and shall be replaced:

2x 22pF Class Y
3x 0.1uF Class X
2x Resistors
2x 220uF Electrolytics
1x TRIAC – This was not faulty but the legs snapped on removal of the clamping bolt.
1x Inductor – Just for inspection.

Bare PCB

The failed resistor had become quite hot and burnt the top of the PCB. I cleaned this with a fiber glass pencil and applied a couple of coats of clear nail varnish afterwards.

Back of PCB

The back of the PCB shows some signs of the burning but it is still intact.

Damaged Capacitor

Above is the damaged capacitor next to it’s new replacement.

Strip Down

· daryl

It soon became obvious once the lid was off where the magic smoke had come from and where the problem may lie.

Motor controller

The controller is full of the dreaded ‘Rifa’ capacitors, these are paper capacitors with resin dipped casing that breaks down with heat and age allowing moisture in. Once this happens a bang soon follows.

You can see the 0.1uF capacitor in the centre of the image has split open horizontally and in the background a resistor has also burnt.