TRS-80 Model 4 Non Gate floppy write problem

[Chromedome45]

HI all, I have a Problem with my Model4 where it won't write disks. It reads just fine. I have swapped all the socketed chips and no help.
Also tried different drives also no help. Any ideas? Larry any ideas.

 

[ldkraemer]

Frank,
Check that you are getting the /WE at the FDC. If you have /WE at Pin 2 of FDC check the WG (HIGH)
Signals out of the FDC IC to the Floppy Drives from Pin 30 of the FDC. This signal is inverted to the
Floppy Drives.

Larry

 

[Chromedome45]

Ok will do Larry. I will let you know

 

[ldkraemer]

Frank,
If your Model 4 has the TANDY Power Supply with a Single row of Pins one one end
of the Power Supply, you need to remove the Supply and check the solder around each
Pin with a magnifying glass. You will find little circles where the Pin isn't soldered well
to the PCB. Re-flow the solder with Kester Rosin Core, and it will be fine.

Also if your Model 4 has Tandon TM-100 Series floppy drives, open the Floppy Door and
look at the hinge area with a Flashlight. If you see two short White Pins, they need to be
replaced with a full length Brass Rod. You might also have a Hinge part that is broken and
needs to be replaced. I've got SPARE parts that are Resin Printed with TOUGH Resin.
Let me know, and I can send you a couple kits to fix your Model 4.


Larry

 

[ldkraemer]

Frank,
Any progress?


Larry