How To: Mod C-100 deck door from 777 deck door

Lasonic TRC-920

Moderator
Here is how you convert the deck door from a Sharp GF-777 to a Conion / Helix C-100

I started with deck door #2 from a donor 777 (thank you to THAFUZZ for hooking me up with this door)
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The Sharp GF-777 door is very similar to the C100, but it is longer side to side and slightly taller. But the soft eject gear is in the right spot, as well as the pivot's and open limiters.

Start by disassembling the door parts..

The plexiglass simply slides up and pops off. But there is a touch of glue at the top which can be loosened with an exact o knife. Then it just pops up.
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Next remove the cassette cradle and spring. The cradle is held in place with a single dimple at each end. Just be gental and it will pop right out.
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The position of the spring.
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All deck door parts.
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The 777 door is 142.74mm long.
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The C-100 deck opening is 130.14mm.
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The 777 door is 78.83mm tall.
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The C-100 deck opening is 79.72mm tall.
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Using the calipers, I scribed lines in the door. The outside line is the exact measurement, the inside line will be my door edge and the gap between is my cut line.
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I used a typical Dremil tool with a 15/16" x 1/40" cut off disc. Set the speed to it's slowest setting. When cutting plastic, it will heat up quickly, when it does, it melts and turns to goo. You don't want that. Do not try to cut through the full depth of the plastic. Instead, score a line down the full length of the cut line. Then go back and cut it again. Keep moving down the length. This keeps the plastic from heating and melting. If your blade becomes filled with melted plastic, replace it. Keep the blade clean for a clean cut. As plastic melt and debris builds up on the cut line, pause, let it cool and chip it away. This, along with a steady hand will make for clean precis cuts.
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My first cut is near the bottom. I'm going to cut out the hinges to possibly graft them in later, so I want to make sure I don't damage them.
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I cut the side above the hinges off first.
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Here are the hinges. I will set those aside till later.
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The length of the door now fits.
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The 777 door latch is at the top and will not be needed on the C-100 and will need to be removed for clearance purposes. So it is cut off.
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Now it's time to trim the bottom of the door to give us our top to bottom fit.

Remove 1.69.mm off the bottom of the door.
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After the cut.
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Now the door fits in the opening.
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The ends of the plexi need to be cut down to fit the new width of the door.

Take 6.98mm off each end.
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Cutting the plexiglass with the cut off wheel requires going even slower. All these surfaces will require sanding to make them flat and even, but still go as slow as possible.
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It's time to start making tiny fitment modifications to the door. This will require small bits of trimming in various parts of the door. I have done my best to document each step and each little cut and trim, but you will still need to make small adjustments to make it fit nicely.

First is a cut to provide clearance for the eject latch. Later, I will make a post for the eject latch to hook on too. But for now, we need the latch to clear the internal structure of the door.
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Next is to provide clearance of the cassette slide guides at the rear of the cassette bay in the radio. I am tentatively trimming off 4.52mm to start with.
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Using the calipers, I scribed a cut line into each side.
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Then made a notched cut into both sides.
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Some material removal was needed near the eject latch again to provide more clearance.
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At the bottom of the door you will find these two pins. They are not hinge pins, but attachment points for the spring that will push the door open. I have removed a slight amount of material to get the door to sit more flush to the face of the box.
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With the cassette cradle back in the deck door, I test for fitment. The door will need to be lowered to make room for the plexi at the top of the deck door.
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I removed this corner of plastic near the eject latch to both give more space for the latch and more clearance to the back wall of the deck bay.
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A tiny bit of material removed here helps the door fit more flush to the face of the radio.
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Next is to provide clearance at the bottom of the pivot/limit stops. This allows for the bottom of the door to be more flush with the face of the box.

Here is where you need to remove a small amount of material.
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With material removed.
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The door is starting fit into the face of the box now.
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Tiny adjustments now need to be made.

I rounded out the bottom of the spring pins to allow the door to open smoother.
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Removal of material here will provide a better fitment and flusher mounting of the door.
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A chamfered edge across the bottom is required so the door can open smoothly.
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It's now time to trim the bottom of the door face.
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I reinstalled the plexi to the door and made my cut from the back of the face using the door as my guide. I then used sandpaper to even the edge. I used the same cut off wheels to cut the aluminum, but at a higher speed setting. Wear eye protection.
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I used a Scotch Bright pad and alcohol to clean up the aluminum a little and remove the text that was on the door.
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The reassembled door, installed on the radio.
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What is next....

Graft in the hinges or make new hinges
Make a spring to push the door open
Make a post for the eject latch to grab
Adjust the gears for the soft eject
Adjust fitment once all these items have been completed
 

Hisrudeness

Member (SA)
Some awesome work work and a thorough write up. Plenty of doorless boxes of this type out there.
Mods should sticker this one?
 

blu_fuz

Well-Known Member
Staff member
Back to it in 2018! Super glad to see someone actually post how this was done. Probably a few different ways to hack away at it, but yours looks pretty straight forward. Good job.
 

Transistorized

Member (SA)
Wow. This makes my little door mod look like childs play :bow:

Brings a question to mind. Why are so many of these missing doors? Was it a popular thing in the 80's to rip off the door or were they just prone to breaking?
 

floyd

Boomus Fidelis
Transistorized said:
Wow. This makes my little door mod look like childs play :bow:

Brings a question to mind. Why are so many of these missing doors? Was it a popular thing in the 80's to rip off the door or were they just prone to breaking?
These have a lock on the door when the belts go bad the door won't open because the deck gets jammed up.
Basically their all ****ed up because somebody broke em to get the tapes out.
 

Lasonic TRC-920

Moderator
Hisrudeness said:
Some awesome work work and a thorough write up. Plenty of doorless boxes of this type out there.
Mods should sticker this one?
Thanks man, soon there will be ton's off 777's missing deck doors so people can make C-100 doors :-O :bang:

blu_fuz said:
Back to it in 2018! Super glad to see someone actually post how this was done. Probably a few different ways to hack away at it, but yours looks pretty straight forward. Good job.
A few months back when I got this radio I started looking for threads on this subject. Over the years I have heard stories of the fabled 777 mod to C-100 but after a thorough search of Boomboxery, I found only one thread from Glucifer. In his thread, it was a description of frustration and countless attempts. It's didn't go into allot of detail and if I remember correctly, he kind of just left it open ended.

So, I wanted to see if it was actually possible and if it was, write up the definitive thread with as many pictures and details as I could so someone could more easily follow, duplicate and hopefully improve on it.

BTW, nice to be back in the game. I wasted too much time last year on "other peoples projects".

Transistorized said:
Wow. This makes my little door mod look like childs play :bow:

Brings a question to mind. Why are so many of these missing doors? Was it a popular thing in the 80's to rip off the door or were they just prone to breaking?
Thanks T, Your door project is of equal value. It's also something C-100 owners deal with all the time. If we don't figure this stuff out, no one will.

JVC Floyd said:
Wow. This makes my little door mod look like childs play :bow:

Brings a question to mind. Why are so many of these missing doors? Was it a popular thing in the 80's to rip off the door or were they just prone to breaking?
These have a lock on the door when the belts go bad the door won't open because the deck gets jammed up.
Basically their all farked up because somebody broke em to get the tapes out.
WHAT HE SAID!

This is the story I have always heard. I have an Sears Roebuck SR2199 that has this issue. The bigger problem is, you can't take the front off the radio without the deck door being open and you can't open the door if the deck heads are stuck up! :bang: :bang: :bang: Catch 22.
 

SLO

Member (SA)
Awesome work Chris! Good to see you back at it. Seems like alot of patience is the key here to this mod, but it came out sweet man.

Transistorized said:
Wow. This makes my little door mod look like childs play :bow:

Brings a question to mind. Why are so many of these missing doors? Was it a popular thing in the 80's to rip off the door or were they just prone to breaking?
Another mythical explanation was that breakdancing crews of the 80's would sometimes remove the cassette doors from their boxes in order to change a cassette tape FAST to keep the music bumpin, especially during a breakdance battle. Makes sense to me, but not sure of the validity of this.
 

floyd

Boomus Fidelis
Another thing people don't realize about the spare tape drawers you have to push in on it to open it most people think you just pull out and that's what breaks the mechanism.
 

Lasonic TRC-920

Moderator
SLO said:
Awesome work Chris! Good to see you back at it. Seems like a lot of patience is the key here to this mod, but it came out sweet man.

Wow. This makes my little door mod look like childs play :bow:

Brings a question to mind. Why are so many of these missing doors? Was it a popular thing in the 80's to rip off the door or were they just prone to breaking?
Another mythical explanation was that breakdancing crews of the 80's would sometimes remove the cassette doors from their boxes in order to change a cassette tape FAST to keep the music bumpin, especially during a breakdance battle. Makes sense to me, but not sure of the validity of this.
Thanks SLO, I have more work to do. Next I need to create the hinges and set the correct pivot point so the door will open and close properly. But it's coming along

JVC Floyd said:
Another thing people don't realize about the spare tape drawers you have to push in on it to open it most people think you just pull out and that's what breaks the mechanism.
Interesting. I need to work on the drawer on this one next. I have a bag of parts, need to figure out what all that means!
 

Lasonic TRC-920

Moderator
The next step in the process is making this a functioning deck door that opens when you press the eject button, latches when pushed closed, accepts a cassette and plays the tape as it's suppose to.

In order to do that, we must build out the hinges and that is what is next.

The C100 hinges are not at the very bottom of the door. They are just off the bottom. This means that while 99% of the door is above the hinge, 1% is below, which causes the bottom part of the door to kick backwards under the door.

In this picture, you can see the hinge post on the C100 chassis.

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We are going to use the hinges that we cut out of the door previously and graft them into the door.

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In the picture below you can see where I have milled a "Half Hinge" into the deck door with the Dremil. This allows the deck door to sit flush with the chassis and align the door to it's pivot point.

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With the door installed and using the "Half Hinges" as our position locator, we can pivot the door on the hinge to check clearances. What we find is that the bottom of the door will need to be trimmed to allow the door to open fully and keep the half hinges in full contact of the hinge posts at all times.

I start by taking a measurement and then scribing a line across the bottom of the plexi of the deck door.

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Then using the Dremil with the cut off wheel I slice the bottom of the door off.

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I reinstalled the plexi to the door and then trimmed the bottom of the door off.

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The next thing to cause opening interference are the spring attachment points for the original 777. I wanted to utilize these, but they are in the way and limiting the opening of the door, so they will have to go.

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And they are cut off with the Dremil and cut off wheel.

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Next is to trim down the hinges and begin the grafting process.

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I want the hinges flush in the door chassis. So, I am going to open up and slot for the hinge to fit into. I start by drilling and opening.

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Using an exacto knife I was able to trim the opening of the hole precisely to the size of the hinge for a tight fit. You can see how the hinge now sits flush in the door and is perfectly lined up with the milled in half hinges.

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This side of the deck door is covered by the plexi, so it's not a visual issue.

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A tiny bit of material will need to be cleaned to make room for the hinge pin.

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It looks factory!

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Now to secure it in place. What I found to work best in this situation was to use a tiny amount of regular super glue in the micro crevasses and then I used a small thin piece of sheet metal with hot glue and pressed it on the back which further pressed the glue into the crevasses. While the glue was hot I pressed firmly, sandwiching all the pieces together.

(Sorry for the lack of pictures in the process.)

This combination of two glues really locked the hinge in place.

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I placed a small bit of hot glue on the inside over the grafted hinge which further encapsulated it in glue.

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I repeated the process on the other side.

The last bit of adjustment to the hinges was milling a slight channel in front of the hinges that allow them clearance to drop in over the hinge pin.

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Now with the door installed, it opens and closes with no interference from the top, bottom or sides.

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Next on the list is the eject spring, close latch and fine tuning.
 

Cpl-Chronic

Member (SA)
Man, what a job! Flub up any 1 step & you're back to zero again with a deck door that's toast! You did an amazing job on the door & on the write up.
 

Lasonic TRC-920

Moderator
Thanks guys, it's coming along. Hopefully this will help someone down the line create their own C100 deck door!


Cpl-Chronic said:
Man, what a job! Flub up any 1 step & you're back to zero again with a deck door that's toast! You did an amazing job on the door & on the write up.
It's funny you mention the fact that one Flub and it's starting from scratch as that thought ran through my head today. If I had to do it again, I think I could go through it much faster. But I really don't want too. :blink:

So much of this is putting on the door, looking at it, finding the interference points and making small cuts, then check it again and trim a tiny bit more.

The big part is next and that's getting the latch pin lined up on the first shot, because it requires drilling a hole and I really only get one shot at it and I can't see where it needs to go because the door it closed....so yeah, I got that going for me.

Then I need to find a new way to set up the opening spring.

The door does close with the tape in it and it's located in the right spot, so I believe that isn't going to be an issue. But we will all find out soon enough!
 

mancardo

Member (SA)
Lasonic TRC-920 said:
Thanks guys, it's coming along. Hopefully this will help someone down the line create their own C100 deck door!


Man, what a job! Flub up any 1 step & you're back to zero again with a deck door that's toast! You did an amazing job on the door & on the write up.
It's funny you mention the fact that one Flub and it's starting from scratch as that thought ran through my head today. If I had to do it again, I think I could go through it much faster. But I really don't want too. :blink:

So much of this is putting on the door, looking at it, finding the interference points and making small cuts, then check it again and trim a tiny bit more.

The big part is next and that's getting the latch pin lined up on the first shot, because it requires drilling a hole and I really only get one shot at it and I can't see where it needs to go because the door it closed....so yeah, I got that going for me.

Then I need to find a new way to set up the opening spring.

The door does close with the tape in it and it's located in the right spot, so I believe that isn't going to be an issue. But we will all find out soon enough!
That's just great work there chris!!!
Thanks for sharing. :thumbsup:
 

Lasonic TRC-920

Moderator
mancardo said:
Thanks guys, it's coming along. Hopefully this will help someone down the line create their own C100 deck door!




Man, what a job! Flub up any 1 step & you're back to zero again with a deck door that's toast! You did an amazing job on the door & on the write up.
It's funny you mention the fact that one Flub and it's starting from scratch as that thought ran through my head today. If I had to do it again, I think I could go through it much faster. But I really don't want too. :blink:

So much of this is putting on the door, looking at it, finding the interference points and making small cuts, then check it again and trim a tiny bit more.

The big part is next and that's getting the latch pin lined up on the first shot, because it requires drilling a hole and I really only get one shot at it and I can't see where it needs to go because the door it closed....so yeah, I got that going for me.

Then I need to find a new way to set up the opening spring.

The door does close with the tape in it and it's located in the right spot, so I believe that isn't going to be an issue. But we will all find out soon enough!
That's just great work there chris!!!
Thanks for sharing. :thumbsup:




Thanks brother. I can't wait to get the decks rebelted and finish the final steps with this project.

I'm no Gordie, but damn it, I finally got me a C100 and now she has a deck door! :thumbsup: