Coping with Cable Denial #2

The Jerrold 450 Hack

by Prowler

I must commend Cap'n Dave on his excellent review of cable TV operation and equipment in the Spring 1994 issue.  In this article, I hope to provide some methods for coping with cable denial at a low cost.

Given the price of cable TV these days, one should be motivated to explore some do-it-yourself methods for receiving cable.  You must however be willing to endure the cost of basic cable service.

Basic cable (everything except pay channels) can be received at your house without using a converter box if you have a "cable-ready" TV.  If your TV is old or if you order the pay channels, a converter box will be issued for an additional monthly rental charge.  You do not, however, have to rent your cable equipment from the company if you purchase your own box.  This is actually a cheaper alternative since it will usually pay for itself within a year's subscription of cable.  Also, you do not always have to own the most up to date converter box to get the job done.  Typically, the boxes issued are the newer type converters which are addressable and descrambling.  These are becoming the norm due to widespread use of newer protection schemes and for access to pay-per-view type channels.  It is, however, usually possible to get the same cable access using the older non-addressable and descrambling boxes.  Since these boxes are not used much anymore, they can be purchased for a relatively low cost (around $30 to $50).

The difference between the addressable and non-addressable boxes is as follows: Addressable boxes have a unique number and can be programmed by the cable company remotely to control operation.  This includes enabling and disabling the descrambling on the converter box.  Non-addressable boxes require a chip that determines what channels will be descrambled.  This chip is obtained from the cable company with the box when you order your channels.  This is a pain for the cable company since the box must be opened and modified to facilitate changes in your cable service.

The newer addressable boxes fixed this problem since they never need to be opened to handle any class of cable service.  You have probably heard stories about people who order all the pay channels to have their addressable boxes enabled, then unplugging the unit to prevent the box from disabling when they cancel the service.  This will leave your box settings on "descramble all" until the cable company turns it off is only a temporary fix because most cable companies send out a periodic signal to prevent this sort of thing from happening.  This can be once a month or once a day, you can never tell.

Basically the computer at the central office looks through the customer database and sends the message., "all paying box numbers enable, all other numbers disable."  So much for your free cable service.  To avoid this, you can always purchase your own addressable box and get the "technician's kit" that is usually labeled "for testing purposes only."  What you will get will be a ROM chip that replaces the EEPROM found in the box that stores the cable settings.  This ROM of course has all the channels enabled and cannot be reset by the cable company no matter what they do.  An ideal solution if you have the money and know what you're doing.

An addressable box usually costs about $150 and the kit is around $60.  You also must have some experience with electronics and soldering since there are a number of modifications to be made inside the box.  This is simply too much of an expense considering the low cost of non-addressable boxes that can have their descrambling enabled without a costly kit.  Not to mention the fact that ordering these kits is suspicious if you don't own some kind of cable service company.  The manufactures don't ask but someone could be watching, you never know.

To get yourself started here's what I suggest you do:

First, find out what type of boxes that your cable company uses.  Check the sticker on the bottom of the box for manufacturer and model.  One of the most common manufacturers is General Instrument (GI) and I will be covering these types of boxes.  A newer type of GI addressable box is the Impulse model.  If your cable company uses these of other types of GI converters you are in good shape.  GI also manufactures compatible non-addressable boxes with the model name Jerrold.  This is the model you want to obtain.  These older boxes are very common and can be ordered from fine publications like Nuts & Volts Magazine.  You can also find these at electronics shows, hamfests, and other such gatherings.  Also, since these boxes are on the way out, you can sometimes find them in a Dumpster behind your local cable office.  It is not cost effective to keep and repair these boxes when the cable company can rent newer addressable type boxes that provide hassle-free service.

  

So, as cheaply as you can, get yourself a General Instrument Jerrold 450 model.  They are identified on the front next to the LED display and have a keypad on the top right.

Once you get a Jerrold 450, hook it up and make sure it works with your cable system.  Put your TV on channel 2, 3, or 4 and you should be able to tune in all the cable stations.  The pay channels will appear scrambled unless you got lucky and have a "fixed" box.  Pay close attention to the scrambled channels.  Do you get sound on these channels but a scrambled picture?  If so, you will probably be able to get these channels.  If the picture and sound is fuzzy (not just scrambled) there is probably a negative trap in use and you will not be able to get these channels without modifying the trap (not recommended).

Now that you have your box you must get it open.  More often than not, security screws are used to make it a hassle to open the box.  What you can do is use a small file to cut a notch in the head of the screw then use a standard flat-head to get it off.  Or you can just drill out the screws and replace them with normal ones.  Incidentally, the screws for common PC cases will fit and are perfect for this job.

Once you have gotten it open, the inside should look like the above diagram (top view).  Obviously, the only component we are interested in is the unscrambler (Part A).  It is a circuit board with a small metal box attached to the back.  The circuit board is attached with tabs that are inserted through the bottom of the case and then twisted to hold it in place.  There are several wires connected to the circuit board, but usually with enough slack to move the board around once freed from the bottom.  Use a pair of pliers to twist the tabs back and free the board from the bottom carefully.  You do not have to cut wires to get it loose.  Once you have it loose, take a look at the front of the board (the component side).

The area with the asterisks (****) is the area of interest.  Do not be surprised if the whole board except for the chip socket is covered in blue epoxy.  This is done to prevent someone from viewing or modifying the circuit.  This, however, does very little once you know where the key point for modification is.  In this case, we will be removing components from the circuit board from the spot indicated.

Right next to where the bottom wire connects are four vertically mounted diodes.  They start approximately three inches from the left of the board.  This will not be evident due to the epoxy coating but you can use the traces shown as a reference.  Removing these diodes is the key to permanently enabling descrambling on the box.  What you will need to do is carefully use a drill with a grinding bit to remove the epoxy in this area.

You will notice that the diodes are covered in a small piece of white cloth.  Once you see this, you will know that you are in the right area.  If you expose a piece of this, you can sometimes pull the cloth and crack away the epoxy covering the diodes.  You could also just grind right through the diodes as long as you do not cut any traces or cut through the whole board!  You must be careful, there are traces next to and underneath the diodes.

The diodes are right next to one another so once you expose one, the remaining three are easy to find.  Once found, use pliers to cut them from the board or simply grind them away.  If you accidentally cut through a trace, scratch up either side of it and put a drop of solder in to fix it.  Once this is done, you are ready to complete the modification.

Obtain a 1N914 or 1N4148 diode (very common).  You will need to insert this in two of the holes of the chip socket, specifically pins 7 and 8 which are the bottom-right holes in the socket.  The anode goes into the far bottom-right hole (8) and the cathode (side with the black stripe) goes into the hole next to it on the left (7).

And that's it!

Your box is now hard-wired into descrambling mode.  Put the circuit board back in place and hook up your box.  Check to see what channels you are now pulling in.  You should be getting one new channel at the very least.  Most cable companies use different protection schemes for the different pay channels.  Your modified box may or may not handle all the different protection in use.  One problem with the older boxes is that new protection schemes have been created since the time the boxes were designed.  This again can be overcome without incurring significant expense.

One feature that the newer addressable boxes have is the ability to handle 12 dB cable signals.  The older boxes only handle the 6 dB mode that was standard during their time of manufacture.  A new protection scheme was developed that uses an alternating 6 and 12 dB signal and is commonly known as Trimode.  You may notice this effect when trying to view the pay-per-view channel in your area.  It may be unscrambled for one minute and then scrambled the next when the signal goes to 12 dB.

What can you do to remedy this situation?  Well, it just so happens that a sub-box was developed for companies that still used the older boxes but wanted to use Trimode signals.  This unit is called the Starbase and is also manufactured by General Instrument.  These too can be ordered from electronics magazines and are much cheaper than the old converter boxes.  This is because they are nothing more than a descrambling unit designed for 12 dB signals.  They typically have an AC adapter to power the unit and come in a small flat case designed to sit underneath your converter box.  The circuit inside is very similar in design to the one in the box.  They also rely on a chip to enable channel descrambling.

So, as you can imagine, the Starbase can be modified just like the box.  Fortunately, the Starbase circuit boards are usually not covered in epoxy.  You should be able to immediately see the row of four diodes that need to be cut.  Then by putting a 1N914 diode into the chip socket you will have completed the modification.  You will then be able to see all cable channels not hindered by an outdoor negative trap, including pay-per-view which will now be on 24 hours a day!

Depending on your cable company, a Starbase unit may not be required.  In any case, it is a small expense for almost total access to cable.

I feel it prudent to mention that use of a modified cable box is of course illegal and should be taken into consideration.  If you're caught using this equipment, the cable company will definitely prosecute.  This is due to the fact that they really have no method of determining whether or not you are stealing cable.  Most people are caught out of sheer stupidity.

I will give you a few examples...  One day the cable company decides to unscramble all the pay channels for about 2 minutes.  During this time they broadcast a scrambled signal with an advertisement for free merchandise or a contest, etc.  Since your box descrambles all signals sent down the line, it will descramble the ad.  Lots of stupid people grab the phone and call in to get the merchandise.  "Come on down and get your free stuff," says the operator.  When you get there what you find is a warrant for your arrest.

As a rule, never call in about things you have seen on channels you don't subscribe to.  Sounds pretty straightforward right?  It's amazing how many people the cable companies bust using this ploy.  Another problem is that cable companies have trucks that they send out from time to time to scan neighborhoods for signal leakage.  If you have run another extension in your house and used cheap splitters and connectors, there will be leakage that the trick will detect.  Your account will be checked and you could be busted.  This could really suck if you're also using a modified box.

As a rule, always spend the extra dollar for decent equipment and do the job right.  Buying a decent cable signal amplifier is also highly recommended.  This prevents the company from accurately determining what you are running inside the house.  Even if they check your signal out at the pole, everything will appear normal.  Connect one of these first on the line inside your house.  Everything beyond it will not be detected.  The better the amplifier, the better the protection.

Lastly, never leave you cable equipment visible from outside your house.  Your neighbors or a passing technician may notice it through a window.  This can obviously lead to an uncool situation.

In conclusion, given the wide open structure of cable TV service and the availability of inexpensive equipment, you should be able to come up with a working system regardless of area or cable company.  Do some experimenting in your area.  Start at the bottom with the cheapest equipment you can get your hands on and see what works.  It will usually be determined by the brand the local cable company uses.  Anything this company manufactures should be fair game.  Your entry level box should be non-addressable with descrambling capabilities.  Add-on products for the box will usually be much cheaper than the box itself.

With all this in mind, be careful and happy hacking!