About Me

Texas Tandy Restorations


Restoring Tandy & TRS-80 Past, for the Future.

Original Specs:

Model 3, 48K, Factory upgraded memory, disk drive, and high resolution graphics card.

Previous Owner: Vickers Industrial inc. (as per audit stamp)
Note: System did not come with an RS232C Board.

1. System refuses to boot at all properly (screen full of random characters
2. Display adjustment buttons frozen.
3. No disk drive access on boot.
4. no Boot to CASS? mode.
5, smoking Rifa then loss of power on monitor.

Sometimes very fun to leave on 30 minutes to get all the bugs up in the air at once.

At this point I turned the unit off and proceeded to a tear down. I tear everything apart to be able to inspect everything, as the HRG (high resolution graphics controller) See image to right; is connected to main board everything needs to be torn down.

Removed the HRG board and connected The main board without it. (since it was an optional board it permitted me to get closer to test main board. 

Tested the Video board, and found it to be faulty, so replaced it with a known functional board, and got an image. showing scrambled characters. 

Replaced both power supply with known restored capped PSU.
Tested ram on board, found it to be good. 
re seated all socket chips on main board, still nothing...
Replaced the Z80 and found that the system boots.

Note: Rare for Z80 CPU to be faulty but in this case it was.

After reinstalling the graphic board, the system once again refuses to boot at all. 

Remove the HRG board and system is fine, examined the HRG board closely, re seat all chips I could and then tested the board connected but not re-installed (put a card board between boards to prevent shorts and tada, we have functional system. 

After more research I discovered a longer pin pushing through the shielding that is factory install and touched the frame, trimmed the solder side and reinstalled. and voila problem solved!

Floppy drives where functional just needed a good cleaning, no alignment issue found to be needed.

Keyboard has zero flaws except being nasty dirty. 

replaced the 500K and 500 Ohms Potentiometers to get adjustment  control on brightness and contrast of the screen.

So all in all not a terribly hard restoration, the usual tear down and clean all components and reassembly of course always takes time, but in the end the system really looks great. 

Last night I decided I wanted to Amber monitor on it since I had is on hand I proceeded to the change over from Black and white to Amber monitor and spent time to adjust the cannon, and video controlled board to get it perfectly centered and looking great!

All in all my favorite restoration so far.

Final Specs:
Model 3, 48K HRG w/ Amber Monitor, Dual Tandon Drives.

System will be for sale at the Tandy Assembly In Ohio Sept 27-29th.

To see all images, click on the gallery below.

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