Last modified on 5-12-94: some additional info has been gathered, and new data collected on some mods, but these are the basics to go with. --Sherrod ============================================================================ I'll go ahead and post the mods I know of for the 100XLT. These have been collected from other netters, and some of this is discussion via e-mail with others. Uniden America Corporation 8707 North By Northeast Blvd. P.O. Box 501368 Indianapolis, IN 46250 Attn: Parts Department Here's the info on current mods I've gathered: Here's some information about the BC100XLT collected from posts and correspondence with people more familiar with the BC200XLT. >From mailed notes: ----------------------------------- Yup, it's the same CPU as thje BC200XLT. And I suspect that most of the pc board inside are the same. The 100 will not have the 800mhz sub-pc board, an extra memory chip, and will have some jumping blocks in different places than on 200. I'll get back to you with the light mod..... > Circuit board on back of Keypad Unit > +------------------------------------------------------------------------+ > | o O v--resistor +---+ +x-x-x-x+ | > |blue^ l l (for battery |400| | SONY | | > |caps ^ mod in 200) |EC | x x | K1013 | | > | |--diode +x-x+ x x +x-x-x-x+ | > | x 2 pins x x 4 pins @side | > | \_ x x | > | / \ 19 pins unused pads 13 pins | > | \_/Spkr. +--------------+ +----------+ | > | / 13 | UNIDEN | 13 13 | LH5008TP |13 | > | x pins | UC-1147 |pins pins | SHARP |pin| > | | 4080FB86 | | JAPAN | | > | | 9E1 JAPAN | text---> | 8851 A | | > | \--------------+ is turned \----------+ | > | 19 pins 90 deg CW 13 pins | > +------------------------------------------------------------------------+ Looks the same as the micom board in the 200. But you're missing a memory chip-- the sony K1013. And the jumpers on pins 15, and 19 would have to be moved. > +=== antenna jack > | Middle removable board with metal sheild around it > V +----------------------------------------------------------------------+ > | Screw hole text printed>==+ +====< raised board | > +-+ |====> O on board | | +---------------------+ | > | | "800 MHz UNIT" <==+ +==> | HCT-55 94V-0 | | > +-| +> ___ ___ ___ | PH-066AB | | > | | ~~~ ~~~ ~~~ | ^ | | > | 3 holes in board, seem | i.d. printed | | > | like holes for vertical | on board | | > | circuit board add'n. ___ +---------------------+ | > | __ ~~~ | > +-+ |__| XTAL +===vertical boards==v | > +-+ L11 v _________ | > | __ __ __ ____________ ~~~~~~~~~ | > +-+ |__| |__| |__| ~~~~~~~~~~~~ "IF UNIT" | > +-+ L7 L12 L13 "WINDOW UNIT" | > +----------------------------------------------------------------------+ This also looks the same. > > So how similar are the guts of the 200? Could it be that Uniden only left > out one board which could just be soldered in place? The guts do appear to be the same. As far as the 800mhz, unit, there are 5 inductors and 2 caps on one side. But 15 caps, 10 resistors, and 4 transistors on the other side. It does not look simple to build on your own. I'm under the impression that the performance of this board is critical. My current scanner measured in at 0.5 microvolts of sensitivity in the 800mhz region but the previous one measured about 2. That's a pretty wide range for a single model of scanner. It might not be so hard to add some memory though. One chip and moving a jumper as far as I can tell.... > Let me know what you figure out as to if anything looks the same or might > be moddable as you posted in you messages about pins 15, 18, and 19, and > also the light mod. One final question: how do you count the pins? > I have noted the beveled edge on the largest IC's, but don't know how > to count the pins. Okay, on the CPU (UC-1147), number one is the first pin to the right of the notch. Number 64 is to the left of the notch. (ie, they go counter-clockwise.) To turn the light on, jump the transistor input that is fed by pin 63 (2nd from the bottom on the left edge--notch to the lower right) to VCC. Pin 26 is VCC and you should be able to trace it to a clear pad near the bottom edge of the board (when you can read the text on the CPU). This pad is the alternate location for a jumper chip that should change the low band form 29-54 to 66-88mhz. (Note, I don't know if all the inductors and adjustments are the same in the European version which employs this configuration.) Well, about those light pins--pins 60-62 are also VCC. So if you want the light on all the time, just tie 63 to the pin or pins above it. You can do this with one find strand of a braided wire and no soldering if you're carely. But your light will be on whenever the power is on. If you want to add a switch, solder the leads--one to that VCC jumper block pad I mentioned, and the other to the transistor that pin 63 leads to. I don't recommend soldering directly to the CPU--it's more likely to be heat sensitive and those pins are pretty small. I hope I haven't confused you. Any more questions, just ask! Brett -- brett@surfpix.princeton.edu Brett Borowski --------------------------------------- Quoted text inside above letter quote is mine (along with drawings), while unquoted sections are his replies. On first diagram above, the chip labeled 400 EC is the frequency control. It operates at 400 KHz, and recently Tom Bodoh (bodoh@dgg.cr.usgs.gov) posted that he had a few extra crystals to sell which double the clock frequency to 800 KHz. I did this mod, and am pleased with the faster performance. Now it scans 40 Ch./sec., samples priority twice as often, delay time is cut in half, and light on time is also twice as short. However, if, like me, you do the light mod and put in a switch, you won't have to worry about the light part. If you are interested in ordering the crystal for doing this yourself, and also if you want to make your rate 2.5 times (approx) the original rate, the manufactureer is Murata Erie, North America, Inc. Rockmart Industrial Park P.O. Box 487 Rockmart, GA 30153 (404) 684-7821 M.E.N.A. Part Number CSB1000J This is a 1000KHz crystal, instead of the original 400KHz crystal. Results show something around 50 ch/sec scan rate, priority sampling rate of ~.8 sec, light delay of ~6 seconds, and VHF search rate of ~3.5 sec/MHz. To get more reliable results, (and to be sure your scanner has more time to sample each channel for activity and get a more accurate result), you might want to get the 800KHz crystal, which operates with very few side effects other than just about doubling any clock-related operation. About adding 800 MHz reception to the 100XLT: since, as noted above, the 100 lacks a sub-board required and present in the better cousin, the 200XLT. This sub-board is in direct line with the antenna, and I suppose its function is to downconvert the 800MHz to a more useable frequency before it is lost inside the sanner circuitry. Without this board, you can move the jumper on the CPU to let it access the 800-900 numbers from the keypad, but there will still be no method of receiving the signals. The circuitry simply isn't there. UNIDEN refused when I talked directly with them to sell the 800 MHz board. They will sell all the parts minus the PCB itself: I purchased all the parts for the board quite a while back, but without the PCB. I copied the PCB design from the 200XLT manual, and have it laser-printer ready, but have not figured out a cheap way to do a trial board to test everything. The board has quite a number of plate-throughs, and three microstrip patches, and while I did my best to copy the locations and geometries of them, copying a microstrip patch (especially on a board of unknown permittivity, conductivity, etc) is mainly a say-a-prayer-and-hope-it-works business. If I ever finish making a board and install it and try it out, I will be sure to post results. But the lack of the 800 MHz region seems to be the only real difference between the 100 and 200, again other than memory and moving a jumper (as desribed by Brett). Since UNIDEN doesn't even sell this board to the dealers: _all_ repair work on the units has to be done in the original repair factory, I will try to see if it's possible to generate the board myself for areasonable cost producing reasonable results. Notes on opening the unit : Remove the back two black screws, obviously: next pull off battery pack and undo the two screws holding in battery spring in middle of bottom. Then lift back end of bottom of radio up slowly, pulling out a little at the same time. it should slide out without too much trouble. Front cover is more problematic: it has a header connecting the keyboard with the CPU etc. board. So lift up on the bottom of the front slowly, and look inside as soon as possible for a small black rectangular box about .25" by .75", and continue lifting slowly while watching that you don't bend the pins. After that, the board with the metal shielding around it comes up with two screws at the bottom of the radio. Reassembly is reverse order, obviously. Again, caution when putting front back on so that you first insert top of front back under lip at top of radio, then make sure to get all the pins in the header correctly. After the first scary time of doing it, you'll see how easy it is, and it should go faster. Always remember the pins on the header will bend pretty easily, though, and that's about all the difficulties. Hope this helps, but don't fry your radio. Be careful about static electricity while working inside the radio, too. >From a post on the internet regarding the internals of the 200XLT, which is the fully enabled version of the 100XLT: ----------------------------------------------- There are three pins on the CPU that are jumped to ground. (15, 18, and 19) They are not labelled in the service manual. The interesting thing about these pins is that there are alternate pads on the pc board that could jump each of these pins to VCC instead. Being the foolhardy soul they I am, I moved each of the little jumping blocks to find out what would happen. The results are mildy interesting and not overwhelmingly useful. I was hoping I could get 30khz spacing in the 800mhz range, but no such luck. Two of the three reduce the capabilities of the scanner and the third changes it. Here's what happened. Pin 19--when grounded, allows the CPU to tune 800mhz freqs. When high, nada. This may be (actually _is_ - Sherrod's note) used in the BC100. Pin 18--when grounded, low band reception is 29-54mhz. When high, it's 66-88mhz. I think this is for European markets. Sadly, one can't tune 29-54mhz when 66-88 in enabled. Pin 15--when grounded, gives 10 banks of 20 channels. When high, the memory is screwy. In bank 1, you get 1-10. It skips bank 2 and in bank 3, you get 21-30, bank 4, 31-40, .... bank 10, 91-100. Leaving you wiht 90 channels. I would have expected 100 channels with 10 in each. Elminated one memory chip and this could be used in a bc100. I don't understand the 90 channels, though. Hope somebody out there find this interesting. BTW, I'm going to be working on an edited version of 200 mod file and I will add the light mod. If there's demand, I'll post. If not, I'll post that it's available and email on request. Brett -- brett@surfpix.princeton.edu Brett Borowski ------------------------------------------------- The above pins are exactly the same on the 100XLT, as they have the same circuitry internally, minus a few critical components. Notes about reception of 66-88Mhz: previously programmed channels are still receieved with no problem, but moving the jumper simply controls the ability to key in new frequencies in those ranges. As (I believe Bob Parnass, maybe someone else) someone mentioned somewhere on the net, since the American version (29-54 Mhz enabled) has different coils and caps for the VHF-LO to optimize reception of a different range, therefore moving the jumper will allow you to receive in that range, but the scanner will be very deaf to anything existant there, and the images from the 29-54 band will walk all over most everything there. ==================================================================== Adding 100 Channels to the 100XLT: Instructions and parts required. The following instructions tell how to add an extra 100 channels to your Bearcat 100XLT. PLEASE READ THE ENTIRE FILE BEFORE PROCEEDING. This modification is only meant for the more recent versions of the 100XLT, for those which use the same CPU board as the 200XLT. UNIDEN has left off some parts from this board, but the solder pads must be in place for the additional parts to restore the 100 extra channels. Before ordering parts to modify your scanner, open up the unit to see if your scanner is modifiable. Look at the CPU board (the one integrated with the keyboard and the display; the same one with the UC-1147 64 pin chip). Look above the upper right corner of the UC- 1147 chip (the CPU) and see if there are 8 solder pads in a DIP configuration; if so, then yours is the later version of the 100XLT which is modifiable. If not, then modifying it is not recommended. Also, if you are not comfortable soldering surface mount components directly onto the CPU board of your scanner, do not attempt this. Remember, it's better to have a working 100 channel scanner than a non-functional 200 channel one. The following parts are necessary for the operation of the scanner: As of May, 1993, the prices are valid: Qty Stock number Scanner part # Description Cost 1 SMBC200XLT Service Manual for the 200 16.00 1 BDEY1127001 IC206 Memory chip 14.74 1 BDBD1777549 Q208 Transistor 00.64 3 BRZY0021001 R250,R252,R253 Jumper chip 00.08 2 BRFD182234Z R218,R219* 22Kohm resistor 00.08 1 BRFD181004Z R222 10 ohm resistor 00.08 Shipping and Handling 04.50 *note: In the 200XLT schematic, these are 22Kohm. In my 100XLT, R218 came as 4.7Kohm, so I matched R219 as 4.7Kohm. However, using the listed value on the 200 schematic means you would have to replace R218 and add R219 as both 22Kohm. If you want to use a 4.7 Kohm resistor to match the current R218, then order part number BRFD18472Z, also $00.08. Also, the service manual is not required, but is nice to have for the parts layout and schematics. Contact the Uniden Parts Department for current pricing and availability. They take credit cards and checks, but obviously, checks take longer to process (it took them three weeks to cash mine). Uniden Parts Dept. P.O. Box 50463 Indianapolis, IN 46250 Tel (317) 842-1036 Fax (800) 323-2641 _Procedure:_ First start by copying down all the frequencies in your current 100 channels. More likely than not, you will lose them in the process of moving the jumpers to tell the CPU that it now has 200 channels. Next make sure you are working in a static-free station. If you don't know about this, you shouldn't be doing this mod. The IC206's leads should have been trimmed to sit flush with the board: if not, then trim them off to the proper length (so the chip sits flush). Set the CPU board so that the text on the CPU is right side up and the speaker is on your left, with the keypad down, obviously. Circuit board on back of Keypad Unit +--------------------------------------------------------------------+ | +--+--empty pads | | | | | | +---+ v v R222\ +x-x-x-x+ | | |400| x x v| SONY | | | |EC | x x R250--v l| K1013 | | | +x-x+ x x ll +x-x-x-x+ | | x x x R223-^ | | \_ transistor-\.. - <-R252 | | / \ .. - <-R219 | | \_/Spkr. +--------------+ - <-R218 +----------+ | | / | UNIDEN | | LH5008TP | | | x | UC-1147 | | SHARP | | | | 4080FB86 | | JAPAN | | | | 9E1 JAPAN | text---> | 8851 A | | | \--------------+ : is turned \----------+ | | :l l:l 90 deg CW | | ^^ | | new location for R253--++--old location of 10Kohm resistor| +--------------------------------------------------------------------+ At the bottom right corner of the CPU, the l's represent the location of the jumper chips in the 100XLT. The :'s represent the alternate location. From the left on the bottom, the first :l combination is the important jumper for this mod. Remove the current 10Kohm resistor and install R253, a jumper chip, across the pads represented by the : Remember as you work with surface mounted components, they are glued to the board, so remove the solder from both ends and slowly pry up the chip while making sure that the solder is liquefied on the ends, and be careful not to pull up traces, etc. They're pretty hard to put back once they're gone :) Install the missing K1013 chip, notch down toward the CPU. The first pair of pads directly beneath the new chip (one of the pads is connected to pin 1 of the new chip) gets the jumper chip, R252. The next set of horizontal pads get the 22Kohm resistor (R219), and replace R218 (the next set of pads down) with the other 22Kohm resistor if it is not 22K already. Next mount the transistor directly above the upper right corner of the CPU. Reading the transistor in the same orientation as the diagram above, the text CI- should be upside down, such that the stripe is to the right. Now look at the left side of the previously existing K1013 chip. Immediately to its left in my version was a diode: this needs to be removed and replaced with R222, the 10ohm resistor. A little more to the left is a open pair of pads; place R250, a jumper chip, there. R223, already installed in mine, was a 10ohm resistor (mentioned only for location reference). Now reassemble the scanner, taking careful not to properly realign the pins on the RF board with the socket on the CPU board. Connect the battery pack and turn the unit on; you might have to cycle it on and off several times to get a display. Enter a frequency in channels 1 and 200, turn the unit off, and turn it back on. If the scanner maintains its memory, then everything else ought to work also. If your scanner does not retain its memory, then check all your solder joints to make sure they do not bridge to any adjacent traces (especially around the transistor and the CPU, and the new chip's leads). Make sure the all the parts are properly located, checking with the schematic if you were wise enough to get one. Also, make sure the transistor and the IC are in the right orientation. After that, troubleshooting becomes your sinking boat, not mine. For cosmetic's sake, you might want to order and replace the following part to make the front appear the same as a 200XLT: Qty Stock number Description Cost 1 KDPT419915Z Display plate for keyboard 00.62 Again, check with UNIDEN for availability and the current price. Standard postmortem disclaimer: I do not assume any responsibility for damage you might do while inside your unit. Nor do I claim that these modifications will work for all versions of the BC100XLT. I make no guarantees about the correctness of this file, but I will do my best to make sure it's right for everything I did to get my unit working. ======================================================================== Copy of AM/FM mode switch mod: mailed to me by Tom Bodoh: neither done on my scanner, so proceed at own risk. They give the right idea of what to do, in case details are sketchy. > Here's the last of the 200XLT mods I know of...downloaded off of a local BBS > here in Chicago: > > Modification for Putting BC-200XLT (same for 100XLT) In AM Reception Mode > > I have come up with a crude mod for the BC200xlt scanner to allow AM > reception in the 136 to 174 range. Why would I want AM in this range you > ask? well I attend several Air shows during the year and the Thunderbirds > use 140 mhz area fregs. As we all know the Uniden switches to FM in this > range, causeing very distorted reception (slope detection). Somebody else > may have already thought of this idea (you?) but here goes. Break the AIR > Trace between dual diode D31 and IC1 pin 8. Connect the center of a single > pole - double throw mini switch to the trace leading back to IC1 pin 8. > Connect one of the other poles to the trace leading back to D31. This is the > "Normal" mode(This just restores what you have cut). Now connect the other > pole to the VHI (VHF HI) line at a easy to locate point. This is the "AM" > mode. What will happen now is when AM is selected the VHF and VHF air band > will all be in the AM mode. UHF and others are not affected. When in the > normal mode everything is just like it always was. I have done this mode > over a year ago so it's still a cloudy in my memory. But it works like this: > The microprocessor sends a high to Q7 to select the AIR mode, by routing the > VHI signal around D31 by means of the switch the AM detector is reselected. > Normaly D31 blocks out the VHI signal allowing FM in the VHF HI range. I > hope my explaination of this mod is clear. It does take some delicate > surgery to do. I also hope I haven't duplicated anyone elses idea. > > Thanks > > From: BILLY WIGGINS ================================================================== This completes my knowledge of the mods for the 100XLT. Any more additions, please mail me and let me know so I may add them into the files... Sherrod Munday smunday@mprg1.mprg.ee.vt.edu smunday@mail.vt.edu sherrod.munday@launchpad.unc.edu *** One Stop Tech Shop BBS / (310) 421-6766 / Long Beach, California *** *** Specializing in Ham Radio, Scanners, Shortwave Listening, Satellites, *** *** Military Aircraft, Groom Lake, AutoCAD, and much more! *** *** Call Today! Share your interests and knowledge! ***