Power Supply Repair

I've completed repairs on Hero's analog power board. I was unable to access RS232 communications because the -10VDC power line was out. It took a shotgun approach and I replaced a hand full of parts on the board. They were either capacitors or related to the operation of the switching power supply and 10 VDC charger pump circuit. The following is from the theory of operation manual:

NEGATIVE 10-VOLT SUPPLY

The ouput signal at the collector (C) of Q301 (replaced) is a square wave, which is derived from the on/off-pulses of Q31. These pulses are filtered and used to generate both the +5VCD and the -10VDC supplies.

C312,D302,D303 (all replaced and it was actually D302 that blew), C313 form a half-wave voltage doubler for the -10VCD supply.

Now I'm ready to put it all back together and give it a smoke test. Once I'm able to run Hero Basic I'll post some more info, photos and maybe some video.

Heathkit Hero Jr. Restoration

This is a photo of my Hero Jr. by Heath-kit. I've taken him out of storage (since 2002) and ordered some upgrade parts from other Hero collectors on the net. One nice find was a all-in-one master cartridge that contains all of the ROMS (including BASIC) with all the programs that were available for the Hero Jr. Also upgraded the ROM to V1.6 custom Y2k and maxed the RAM to a whopping 24K. All parts purchased from www.robotworkshop.com. He now has a new battery too.

My plan is to interface a single board linux computer (Chumby Hacker Board) with wifi connected to the onboard power and serial port. Then I can control and program the Hero via remote. Right now I just got the upgrades installed and now have to go thru and calibrate all the sensors etc. Currently it works with sonar, movements and speech. I just want to get all the sensors 100 % and clean up the chassis before moving on to the Chumby mods. More to come.

For now here are some specs on the Hero Jr taken from this site:

Main Processor

Type 6808
Clock Rate 4.00 Mhz

On Board Memory:

ROM 32K (Robot Monitor)
RAM 2K

Motors:

Steppers: Dteerin - 180 degrees rotation, stepper motor
DC Motor: One Front Drive wheel

Senses:

Sound: Detects and quantifies ambient sound levels over the frequency range of 200 to 5000 Hz. Resolution is 1 part in 256. The sound sensor is essentially omnidirectional.
Light: Detects and quantifies ambient light levels over the visible spectrum. Resolution is I part in 256. Sensor reception angle is about 30 degrees.
Sonar: Ultrasonic - Polaroid type, 4" to 25-foot range.
Motion: Ultrasonic sonar detection (standard). Infrared sonar, six-array configuration (optional).

Keypad and Display

Keypad 0-9, A-F, and Reset. Each key is labeled with proper function (sing, play, poet, etc..)

Speech

Synthesized phoneme-based system. Generates 64 phonemes which can be concatenated in any combination to simulate human speech or various sound effects. Reference pitch Is hardware selectable, and instantaneously variable over four levels of inflection using software.

Power Supply

Battery:

Voltage 6V (Configured as two independent 12V systems)
Capacity 4 Ahr
Charge Rate 1.75A
Charge Time 10 hours
Operating time ?? hours typical

Charger:

Output voltage +12VDC
Output Current 780 ma
Input Voltage 120 VAC