How to open a Chess Challenger adapter

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microhenri
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How to open a Chess Challenger adapter

Post by microhenri »

Hi all,
I have a Fidelity Adapter from an early Chess Challenger with a lose contact inside. I would like to open it in a way so I can close it again in a nice way. The adapter seems to be glued or so and very hard to open.
Does anyone have experience of suggestions how to open this adapter without destroying it?

MicroHenri
Four.nine
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Post by Four.nine »

Hello Micro,

Good news!
Many, many years ago, I opened up an adapter that was glued. You need a sturdy utility knife with a brand new blade.. and with adapter in a vise, carefully cut the adapter plastic at the glue point. Switch the knife blade half way around the adapter to keep a sharp edge. When you get to the end, pry with screwdriver to get the "lid" portion off.

The bad news:
Don't bother. Inside the adapter is a transformer with tiny gauge copper windings: virtually always one of those windings "opens". Like a light bulb, it just dies. One "don't" fix a light bulb...one replaces it. You state there is a "loose contact". Without opening, you don't know what that particular noise even means...if it even has something to do with the problem.

If you do open the adapter up...let the forum know what you found. By the way, that "Fidelity Adapter": Is that the model that is about 30 years old or is it the one that is forty?

Get a new one.

Oh, and the adapter that I once opened? No where to be found. I must have trashed that 20 years ago.
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microhenri
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Post by microhenri »

Thanks Four.Nine.
Now I know why most Chess Challengers do not have the original power adapter anymore. When they break down they will be thrown away.

OK, so there is a chance of breaking it while opening the case, but it is already broken anyway, and I can not use it as it is. There is a chance that I will succeed, and when I don't, I can bye a new one after all.
Four.nine wrote:You state there is a "loose contact".
With loose contact I mean that when I wiggle the wire that does exit the adapter, the chess computer switches on and off. So somewhere inside the adapter or in the cable exiting the adapter there is a broken connection. This is not handy while playing a game. When the power is gone, I have to start all over again.
Four.nine wrote:If you do open the adapter up...let the forum know what you found."
Of course! I will
Four.nine wrote:By the way, that "Fidelity Adapter": Is that the model that is about 30 years old or is it the one that is forty?
The adapter came with a CC7 with a serial number stating that it has been produced in 1980. (Production dates and serial number relations once discussed here on this forum). It is an adapter with nice golden characters and Fidelity symbol. I like the words "better living through science".

Thanks again.
microHenri
Four.nine
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Post by Four.nine »

Wait. Wait. WAIT!

Your transformer isn't bad.
Your adapter isn't bad.

What you have is...ein "wackel-kontact".

All the stranded wires on one of the two lines are not loose, they're "frayed". The wire has been bent back and forth, up and down so often over the years that the stranded wires have actually been "severed" due to mechanical stress. The break happens immediately after the ribbed "strain relief" coming right out of the adapter.

Now, it takes some work ....but this can be repaired.
But, you need a soldering iron, solder, flux, SHARP exacto knife, electrical tape and needle nose pliers (to hold the wires while working).
If the above statement confuses you, then seek out a friend with all these tools and he/she will know what to do.

I believe I have three, maybe four, of my power adapters that have this type of repair.

As an all points bulletin:
ALL of these old power adapters need a little cloth type electrical tape (not vinyl) wrapped around the wires exiting the power adapter for added strain relief.
But...nobody really does this....not even me.
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microhenri
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Post by microhenri »

Yes I know. But it is not easy to repair the broken wires when it is broken so close to the adapter exit. It would be much more easy if it was simple to open the adapter so I could cut out the broken part of the wire and resolder it on the rectifier (Yes it is a DC adapter). This was the reason why I asked.

If you mean that it is possible to repair this without opening the adapter, would you please explain in more detail? I do have al the tooling you mentioned.
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Post by Four.nine »

The adapter wires are away from the adapter body by the length of the strain relief. Right where the strain relief ends (maybe slightly inside the strain relief) is where the break occurs.
Cut the strain relief longitudinally (like a fish) with the exacto knife perpendicular to the strain relief.
(Aside: I charge physician's fees for this advice.)

Now, Use the exacto to "whittle" (consider the SR like it is a small cylindrical piece of wood), the SR material away in small slices, perpendicular to the SR cylindrical axis. At one point you will feel like you can just peel away the remaining piece of SR: Use needle nose.
Now there are two remaining wires coming out of the adapter that look just like the rest of the wire.
Somewhere in there is the break.
Using a sewing pin and ohmmeter "buzz" out the which wire is broken. In my experience, it's only one. Multiple probes with the sewing pin will show where wire is broken (you may have to flex wire to cause the open...in fact flexing the wire may even show you where the break is).
Once the location is determined, like a fish, carefully "fillet" the bad wire (just that one wire, not both) insulation longitudinally. Split open the insulation and you should see frayed wire in there.
Dump in some flux, maybe a 5 mm piece of sturdier "connector" wire between the frayed wires and bring on the hot iron and solder.

Button it all up with Friction electrical tape ...not the vinyl crap.

Hope this helps
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microhenri
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Post by microhenri »

Image
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microhenri
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Post by microhenri »

Hi Four.nine and All

I did repair the adapter successfully. It was a little tricky.
Thank you Four.nine for all the great tips. Most of them were very useful.

In the image you see step by step how I did repair the adapter. In image 4 you see that the strain relief is a little different then the one you did describe. This type of strain relief did make it a little complicated because I can not remove the strain relief without opening the adapter.

So here is the repair step by step:
1) The adapter.
2) By piercing the wire with a sewing pin and measure the resistance between the connector at the other side of the cable and the pin I was able to locate where the wire was broken.
3) By wiggling the wire right and left the wire was making contact (moving right in image 2) and no contact (moving left in image 3).
5) Open up the damaged wire with a sharp knife. The defect turns out to be very close or almost inside the strain relief. This makes it tricky to repair.
6) By piercing a few sturdy wires into the very short wire sticking out of the adapter I was able to make a larger surface for the soldering.
7) Here the wires are soldered.
8 )As you can see I did also cut the other wire to. This is done to be able to put the heat shrink tubing around the cable later.
9) Here the wire is glued with two component epoxy glue to give it mechanical strength
10) The final result. The heat shrinking tubes can be heated with a solder iron or with hot air. Be careful not to heat the housing of the adapter. The housing will melt.
Four.nine
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Post by Four.nine »

Hello micro:

Bad news: The old Fidelity adapter had a "bushing" strain relief...haven't seen that for decades... in DC power adapters. That type costs too much and has been replaced by a molded "boot" version. Sorry, I gave you some unusable advice.

Good news: You figured the fix out anyway. Nice work and very informative post. Also, the shrink tubing was a very professional touch.

Oh-oh:
I do see some vinyl tape wrapped around the supply. Did you have some separation of the two sections of the supply housing?

👍👍
Four.nine
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Post by Four.nine »

Don't get old. You always forget shit. General comments:

1. Probably 90 % of power adapter "failures" are due to the cable break like the one you just fixed.

2. You can abuse your power adapter cord at will, except for two places:

At the strain relief coming out of the adapter and at the strain relief of the barrel connector that plugs into the chess computer.

So....when you are done with your computer, putting stuff away and you wrap the cord around the adapter ...like I do:

Wrap the cord as if you were holding on to a soap bubble and trying not to break it.
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microhenri
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Post by microhenri »

Thanks Four.nine.
Four.nine wrote:Sorry, I gave you some unusable advice.
No, most of your tips were very useful.
Four.nine wrote:Oh-oh:
I do see some vinyl tape wrapped around the supply. Did you have some separation of the two sections of the supply housing?

👍👍
Oh-Oh No-No, Hi-Hi. This is an optical illusion. I took the photo (image 10) on my kitchen table which is white and shiny. What you see is the edge of the table reflecting in the adapter housing. I agree that this looks like vinyl tape, but it isn't. The housing is, just like Image 1, all original.

👍thnks again👍
Four.nine
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Post by Four.nine »

Excellent work and you have your original adapter back!

I’m glad you didn’t have to open up the adapter. That version of the repair is to be totally avoided.
Your post will help many others with old computers that have “intermittent”, befuddling “Sometimes YES, Sometimes NO” operation (because sometimes...it’s really just the old adapter).
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