Posted on Leave a comment

Wouxun KG-UV950P Teardown & Analysis

Following on from my review, here are some internal views & detail on the components used in this radio. Below is an overview of the main PCB with the top plate removed from the radio.

Cover Removed
Cover Removed
RF Final Amplifier Stage
RF Final Amplifier Stage

Most visible are these MOSFETs, which are Mitsubishi RD70HVF1 VHF/UHF power devices.  Rated for a maximum of 75W output power at 12.5v (absolute maximum of 150W, these are used well within their power ratings. They are joined to the PCB with heavy soldering, with bypass caps tacked right on to the leads.

RF Pre Drivers
RF Pre Drivers

Here is the RF pre-driver stage, with intermediate transistors hidden under the small brass heatspreader.

Power Section
Power Section

In the top left corner of the radio, near the power input leads, is the power supply & audio amplifier section. Clearly visible are the pair of LA4425A 5W audio power amplifier ICs, these drive the speakers on the top of the radio. Either side of these parts are a 7809 & a 7805 – both linear regulators providing +9v & +5v logic supplies respectively. The large TO220 package device is a KIA378R08PI 3A LDO regulator with ON/OFF control, this one outputs +8v. Just visible in the top right corner are the sockets for the speaker connections.

DTMF Circuits
DTMF Circuits

Here are the two ICs for dealing with DTMF tones, they are HM9170 receivers.

Glue Logic
Glue Logic

In the corner next to the interface jack, there are some CD4066B Quad Bilateral switches. These make sense since the interface jack has more than a single purpose, these will switch signals depending on what is connected.

RF Section
RF Section

Here are visible the RF cans for the oscillators, the crystals visible next to the can at the top. The shields are soldered on, so no opening these unfortunately.
Also visible in this image is a CMX138A Audio Scrambler & Sub-Audio Signalling processor. This IC deals with the Voice Inversion Scrambling feature of the radio, & processes the incoming audio before being sent to the modulator.

Output Filter Network
Output Filter Network

Shown here is the RF output filter network, this radio uses relays for switching instead of PIN diodes, I imagine for cost reasons. The relay closest to the RF output socket has had a slight accident 🙂 This is slated to be replaced soon.

RF Output Jack
RF Output Jack

Finally, the RF output jack.

Audio Speakers
Audio Speakers

Here the speakers are shown, attached to the bottom of the top plate. They are both rated 8Ω 1W.

Posted on Leave a comment

Amano PIX 3000x Timeclock

Front
Front

This is a late 90’s business timeclock, used for maintaining records of staff working times, by printing the time when used on a sheet of card.

Front Internal
Front Internal

Here is the top cover removed, which is normally locked in place to stop tampering. The unit is programmed with the 3 buttons & the row of DIP switches along the top edge.

Instructions
Instructions

Closeup of the settings panel, with all the various DIP switch options.

CPU & Display
CPU & Display

Cover plate removed from the top, showing the LCD & CPU board, the backup battery normally fits behind this. The CPU is a 4-bit microcontroller from NEC, with built in LCD driver.

PSU & Drivers
PSU & Drivers

Power Supply & prinhead drivers. This board is fitted with several NPN Darlington transistor arrays for driving the dox matrix printhead.

Printhead
Printhead

Printhead assembly itself. The print ribbon fits over the top of the head & over the pins at the bottom. The drive hammers & solenoids are housed in the circular top of the unit.

Printhead Bottom
Printhead Bottom

Bottom of the print head showing the row of impact pins used to create the printout.

2013-02-13 18.00.09Bottom of the solenoid assembly with the ribbon cable for power. There are 9 solenoids, to operate the 9 pins in the head.

Return Spring
Return Spring

Top layer of the printhead assembly, showing the leaf spring used to hold the hammers in the correct positions.

Hammers
Hammers

Hammer assembly. The fingers on the ends of the arms push on the pins to strike through the ribbon onto the card.

Solenoids
Solenoids

The ring of solenoids at the centre of the assembly. These are driven with 3A darlington power arrays on the PSU board.

Gearbox Internals
Gearbox Internals

There is only a single drive motor in the entire unit, that both clamps the card for printing & moves the printhead laterally across the card. Through a rack & pinion this also advances the ribbon with each print.