[M100] M100 switching power supply troubleshooting

[Jeffrey Birt]

Hi All,

 

I'm working on a M100 that was desperately in need of having the
electrolytic caps replaced. That job was done, and the mess cleaned up. That
being said the power supply section is not working. At one point it did
start working briefly and was outputting a steady 5V and -5V. 

 

The memory battery is charged: VB = 3.3V

VL ~= 5.5V all the way to Pin 4 of OT2.

I ohmed out the +5V and -5V rails to make sure they were not shorted.

 

Measuring across secondary of the transformer, OT2, pins 7-9 with scope
shows a blip on power on. However, T21/T22 are not oscillating. Ohming out
the transformer shows both primary and secondary seem OK.

 

I have done the simple things like checking the diodes and transistors and
double checked that the leaking caps did not cause any broken traces.

 

It looks like if I remove T20 I can isolate the auto power off circuitry.
I'm trying to figure out what T27 and T28 do as well as figure out what
steps to take next. 

 

Since it briefly worked it could be an intermittent short/open or perhaps a
component is right on the edge of tolerance and not letting it start to
oscillate? 

 

Open to any ideas.

 

Thanks,

Jeff Birt

Re: [M100] Improved replacement M200 battery cover

[Brian White]

I like what you did to try to reduce the stress risers as much as possible
for the hooks within the constraints.

bkw

On Sun, Jul 5, 2020, 4:15 PM Steve Glenner  wrote:

> Here is the improved 3D printable M200 battery cover:
> https://www.thingiverse.com/thing:4508352
>
> I have made the side tabs a little more robust with a larger radius
> fillet, increased the clearance of the short edge tabs, reduced the width
> and length vary slightly for easier fit, and added some rib cutouts to make
> a finger grip area for opening the cover. The new model came off the
> printer and went right into my M200 without any post processing other than
> removing the small amount of support material under the hooks and tabs.
>
> I have also added a second model which is a stabilizer part which will
> protect all the hooks and tabs if the cover needs to be mailed.
> If you need a cover and don't have access to a 3D printer contact me and I
> can send one if you cover the shipping and material cost.
>
>

[M100] Improved replacement M200 battery cover

[Steve Glenner]

Here is the improved 3D printable M200 battery cover: 
https://www.thingiverse.com/thing:4508352

I have made the side tabs a little more robust with a larger radius fillet, 
increased the clearance of the short edge tabs, reduced the width and length 
vary slightly for easier fit, and added some rib cutouts to make a finger grip 
area for opening the cover. The new model came off the printer and went right 
into my M200 without any post processing other than removing the small amount 
of support material under the hooks and tabs.

I have also added a second model which is a stabilizer part which will protect 
all the hooks and tabs if the cover needs to be mailed.
If you need a cover and don't have access to a 3D printer contact me and I can 
send one if you cover the shipping and material cost.

[M100] Finally got one!!

[James Zeun]

So since I acquired a DVI for my M100, I've been wanting to put something
in the empty second drive bay. As I had no blanking cover.

I was just about to get one from arcade shopper, when out of the blue I
find my self bagging a 180kb floppy drive, not just that, it's tested and
refurbed.

Just have to wait for it in the post. Had to post something, as I'm sitting
here happy as Larry.

-James

Re: [M100] LaddieAlpha and STARTDISK.COM

[Jonathan Yuen]

My memory of the CPM FCB is that they are there as 8 + 3 characters, padded, 
without any '.'.  But it was a LONG time ago I actually looked at a CPM FCB.  
Which might explain why they are left out of the STARDISK.COM, but I'm just 
speculating, never having looked at the program.

Jonathan

jonathan.y...@mykopat.slu.se

Från: M100 [m100-boun...@lists.bitchin100.com] för John R. Hogerhuis 
[jho...@pobox.com]
Skickat: den 5 juli 2020 00:27
Till: m...@bitchin100.com
Ämne: Re: [M100] LaddieAlpha and STARTDISK.COM

On Sat, Jul 4, 2020 at 12:37 AM Philip Avery 
mailto:pav...@xtra.co.nz>> wrote:
As to the current 8.3 handling, it may or not be helpful with REXCPM depending 
on how it would format an 8.3 filename. I really don't like the fact that 
STARDISK.COM leaves out the '.' but at this point the 
question is do we do it the way it does it or do we handle both ways. Either 83 
or 8.3.

-- John.
I think you're referring to M100 CP/M as REXCPM


I guess I made no distinction because M100 CP/M only runs on REXCPM?

is the hardware (the RAM disk).

Understood.

I'd certainly prefer 8.3 (as opposed to 83) as I've done my end for it and Kurt 
has almost done mComm for it too.

OK.

Padding with spaces to 8-characters for the base name (the part before 
extension), right?

Every client I've seen so far pads it out. Not sure why. Well, with STARDISK I 
understand why. With a '.' the padding is not really necessary.

But because all the clients do, LaddieAlpha presents filenames as padded to the 
client to avoid triggering dependency bugs based on assuming base names come 
back padded.

If I get VT going to where I can test I can finish it. I'll test the high speed 
stuff with Steve's image utility, but you'll need to add it too to 
IMPORT/EXPORT since LaddieAlpha will be started in one mode for CP/M operation 
and generally stay in that mode. Wouldn't want to have to exit and start back 
up with different options.

-- John.
---
När du skickar e-post till SLU så innebär detta att SLU behandlar dina 
personuppgifter. För att läsa mer om hur detta går till, klicka här 

E-mailing SLU will result in SLU processing your personal data. For more 
information on how this is done, click here