does it matter which way you plug in?

[AtariNostalgia]

I am using a step down transformer for US TI99s.

Are the plugs polarized? Does it matter which way I plug them into the transformer?

[apersson850]

As long as you keep track of what's input and output, then no.

[dgrissom]

I'll give this my best shot.  My son and I actually went through a similar exercise on a UK Amiga 600 last month with similar questions about non-US plugs.

 

Modern USA power receptacles are polarized.   However, when the TI power supply was first manufactured the the power supply plugs were not polarized.  Those types of PS plugs can be inserted without polarization worries.

There was a recall/retrofit in 1983 on some of the power supplies that added a polarized extension.  (Green label on the extension cable. Fig3 below)   This can only be plugged in one way.  (I help retrofit some of the recall/consumer alert power supplies in the field in 1983.)

https://www.cpsc.gov/Recalls/1983/texas-instruments-providing-adapter-for-ti-994a-computer

 

 

I hope this is both useful and accurate.  ?

 

[HOME AUTOMATION]

I believe the main reason for the polarization of the safety-adapter, is to keep the fuse on the HOT line, and the NEUTRAL unfused. The transformer based voltage-converters are usually isolated as well. So it should not matter.

 

But if you really want to preserve the adapters intended safety-mechanism, you should ground the wider spade.

 

9 hours ago, dgrissom said:

I help retrofit some of the recall/consumer alert power supplies in the field in 1983.

Do you recall if there was any need/means to mind polarity when attaching the safety-adapter?

 

 

Edited August 7, 2020 by HOME AUTOMATION

[dgrissom]

8 hours ago, HOME AUTOMATION said:

I believe the main reason for the polarization of the safety-adapter, is to keep the fuse on the HOT line, and the NEUTRAL unfused. The transformer based voltage-converters are usually isolated as well. So it should not matter.

 

But if you really want to preserve the adapters intended safety-mechanism, you should ground the wider spade.

 

Do you recall if there was any need/means to mind polarity when attaching the safety-adapter?

 

 

A good question.  (However, it is one that I can only fully remember bits and pieces of.)

Note:  You can stop reading now if you expect a good answer to your question.  ?

 

What I remember:

I was working part-time in Birmingham, AL as a TI Product Representative,  (I demonstrated TI 99/4A's in retail stores).

During the recall*/retrofit we were used to retrofit existing inventories in all retail stores in our area.  I remember there being a strong sense of urgency bordering on panic to get the job done as quickly as possible.  A side note: as part of a user group we supplied coupon type flyers to the group members to get them aware of how to retrofit their power supplies if needed.  (I think that they were to contact TI-CARES.)

It was a hot dusty job working in most of the store's stock rooms.  In some cases, there were over 100 units to be reviewed and retrofited.

 

TI supplied us with a kit that contained the adapter cords, green safety checked labels (box and transformer), glue, and diagrams.  I think that we were supplied with letter to provide to store management that described the problem and a request for them to provide us access to the stock.

 

We were to add the adapters to specific power supplies (based on our instructions, diagrams, and limited training).

 

We had to open every TI carton in inventory and check the supply.  If the supply required the retrofit we would attach it with glue and apply the label to the power supply.   We had to carefully repack the carton.   All cartons, whether they contained the affected supplies or not, were resealed with a "safety checked"  label.

 

What I don't fully remember:

I currently own 2 TI PS's.  One has the adapter and one does not.  While both units resemble each other they are distinctly different in appearance.

My units match what I recall at the time.   The PS power cord and safety adapter on the affected units were lined up with the cord groove pattern and I think/assume the original polarized plug.  BTW, the glue that we were supplied with was extremely efficient, fast drying, and based on my examination after 37 years very permanent!  ?

 

I believe that this incident cost TI a great deal of money and in their eyes market confidence.  This adversely affected them at a critical time and may have contributed to their decision to withdraw from the home computer market.

 

DG

 

*Note:  I call it a recall.  To my knowledge (others may actually know this), I don't remember TI ever directing stores or individuals to return their stock or console power supplies in our area.

[HOME AUTOMATION]

5 hours ago, dgrissom said:

(based on our instructions, diagrams, and limited training).

As is often the case in real life...

 

Just looked at the xformer I'm currently using. It has the green safety checked label, but no adapter, the cord is splined.

 

I think the xformers that needed the safety-adapter, were of the type where the primary and secondary windings, were not physically separated by the bobbin.

 

  P.S. Fun story!

[+Ksarul]

TI also sent registered users a kit that would allow them to perform the mod on their own. I think I may still have one of them lurking about. . .

[dgrissom]

7 hours ago, Ksarul said:

TI also sent registered users a kit that would allow them to perform the mod on their own. I think I may still have one of them lurking about. . .

If you run across it, let me know if the female end is polarized.  I honestly can't remember?!

 

BTW,  My dongle, states that it is to be added to models: AC9500 and AC95000 with specific markings.

 

 

At least I remembered only a few PS's were affected.  ?

[HOME AUTOMATION]

On 8/7/2020 at 3:36 PM, HOME AUTOMATION said:

Just looked at the xformer I'm currently using. It has the green safety checked label, but no adapter, the cord is splined.

It is marked LT10036!

 

I also found a 20237 w/o a safety-adapter. At least this one doesn't have a bogus "safety checked" sticker.

 

I'd guess I have about another 5 of these packed away...

 

I'll probably die in a transformer fire someday...

[Toucan]

On 8/6/2020 at 3:33 PM, dgrissom said:

I'll give this my best shot.  My son and I actually went through a similar exercise on a UK Amiga 600 last month with similar questions about non-US plugs.

 

Modern USA power receptacles are polarized.   However, when the TI power supply was first manufactured the the power supply plugs were not polarized.  Those types of PS plugs can be inserted without polarization worries.

There was a recall/retrofit in 1983 on some of the power supplies that added a polarized extension.  (Green label on the extension cable. Fig3 below)   This can only be plugged in one way.  (I help retrofit some of the recall/consumer alert power supplies in the field in 1983.)

https://www.cpsc.gov/Recalls/1983/texas-instruments-providing-adapter-for-ti-994a-computer

 

 

I hope this is both useful and accurate.  ?

 

 

Here's a question I have, which I have wondered for some time. For the wall mount power supply, there's a little hole at the top of the unit. It aligns with the screw hole on a power outlet cover. Was the idea to take the screw out of the power outlet, plug in the TI power supply, and then screw it back on through the hole? I figured this might help with the weight of the power supply on a wall mounted outlet which is why they might have did that. Only problem I could see is if you needed to unplug it for a fire hazard and couldn't get it off quickly.

[+Ksarul]

That was its purpose--and as you noted, using it could cause issues, @Toucan

[dgrissom]

1 hour ago, Toucan said:

 

Here's a question I have, which I have wondered for some time. For the wall mount power supply, there's a little hole at the top of the unit. It aligns with the screw hole on a power outlet cover. Was the idea to take the screw out of the power outlet, plug in the TI power supply, and then screw it back on through the hole? I figured this might help with the weight of the power supply on a wall mounted outlet which is why they might have did that. Only problem I could see is if you needed to unplug it for a fire hazard and couldn't get it off quickly.

Back then we weren't afraid of them fires.  ? 

Actually, I've seen a number of similar device mounts, today.  Most notably on Security Alarms.

[+OLD CS1]

4 hours ago, Toucan said:

Only problem I could see is if you needed to unplug it for a fire hazard and couldn't get it off quickly.

We worried not about such things in the 70s.  This was truly the last decade when the fittest survived.  Oh, they tried to make things "safe" for us kids with things like "Mr. Yuck," but it was not until the 80s when household safety really kicked into high gear (wusses.)

 

2 hours ago, dgrissom said:

Back then we weren't afraid of them fires.  ? 

Actually, I've seen a number of similar device mounts, today.  Most notably on Security Alarms.

You know how many of those wall warts I have seen disintegrated in my network closets?  Or, if the plastic has not detached, it is warped and charred from the heat of the transformer.  We used to have them on our phone lines, too, putting power on the black/yellow pair for phones with light-up dials or pads.