#173 RF Troubleshooting Tips part 1

well good afternoon everyone hope everyone's having a good day I've had many many emails throughout the past few months about learning to troubleshoot radios and it wasn't until recently wild got an email from a nice young lady that was cutting her ham license and she did a bit of my service and the Highway Patrol Department and she has sent me a nice email asking about troubleshooting so I wanted to start a series just on basic radio troubleshooting now this would not be for the season tech as everyone that's seasoned should already know all the ropes and tricks about testing radios and troubleshooting to get them back up and running now I have two radio television system just came in at some realistic HDX 100 that has some problems and this is one I've been working on for a while that I've had some issues with and one of the first things that when it comes to troubleshooting as you know having equipment to walk on radios and so forth now you know I have a hold of different test equipment this and that and you do not have to have all this stuff a lot of times just a basic digital multimeter will get you by to get things going one of the features that works good with a basic multimeter is an Oreo probe now you know I can just reach over and grab my Heathkit Oriya probe I put bananas a BNC connectors on just about everything I have I can pop it on one of these beings each of it but now Jack plugs pull out the probes coming on the right side and just plug it right in set this thing on AC and away we go you know we have a weird way of testing signals that run through the radio but a lot of people was not more nervous reach over and grab the OREA probe because they don't have one now in this radio this heat get hw8 an RF probe is required to align this radio and what we're gonna do in this video is show you how to build a couple of types of RF probes and the first one we can be building is just a simple advice basic RF probe which you can build and there is the one that's recommended or the H does the Ageless even in the manual now we're good here and we look at the screenshot of that diagram all we can see is a 4.7 Meg resistor a point zero zero 1 micro farad capacitor and a geranium down this could be a 1 in 30 for a or anything equivalent so once this side was capped would be your test point probe decided resistor we go to your both meter or your back into voltmeter so we're gonna build this and we're gonna build another that's a little more elaborate so do basic components of the first or a probe on the orders just a resistor a capacitor and a geranium doubt will also use this piece of number fourteen copper wire as our probe tip you can just cut this out of a letter wiring like you know for your house or whatever and when making or approach you can use a variety of things for the probe body ii poke that we're going to be building it's actually gonna be in this piece of wood inch aluminum tubing and with a coupler in pieces that i 3d printed and these are simply just pot run only inside of each en and we'll put off probes tip and I'll coax through the end of these so this one will be a little different my regular heat get probed is just the aria pro this is the pkew - three probe it's one of the air some you know you'll see some of these to have a switch on it and the switch turns it from an aria probe to an audio program so they also worked real good with signal generators now I do not have a standard Heath can't probe that has the switch in it so we'll be making one of those also now again there's a variety of things you can use from a pin to an old magic marker you know the big ones always a small little sharpie and today what we're going to do we're gonna fill this in an old syringe this is a ten milliliter syringe and it's about 5/8 inch in diameter outside but we're going to just be or our circuit right on the plunger and then insert it into the body so the tip will come now and we'll have a nice little or our pro for testing and adjusting radio circuits so again like to say we're gonna just build this simple probe right in this little trough in the internal plunger and then our probe will come through and stick out the other side like so and we can assemble this and then just slide this back into the housing you ever had to work on it or fix a solder joint on the cable you know you just have to pull it out and your circuit will be right there so one of the first thing we need to do the import these rubber tip off let's go ahead and get us a hole drilled to come up in this trough so we can get off key up there so I'll go ahead and do that off camera and then we'll install off the up take off from the hidden go to hole directly in the center and up in traditional and I've pushed it to tip all the way through you get your depth right so that when you install it into the syringe party that you have enough of the tip sticking out you know and you know an inch three quarters of an inch something like that would be fine so now when I put the brother see along when it's pushed back in it has a lot of resistance and that's gonna hold the whole thing together real simple to do [Applause] so the very force component that will go in behind the tip will be our point double O one capacitor and as you can see on the schematic exactly how that would be so what I've done I've come here now pre-order two small holes and we're simply just going to take our capacitor using lap just a little bit we want to insert it in these two holes they'll help solder this lead to our wire you know they can do that okay then we have our capacitor run through soldered to our probe tip and now we need to put our 4.7 meg resistor II and so what I wanna do is just grab the drill again and I'm gonna pop to more hollow just that simple I'll take our resistor will get our resistor in here now I'm go ahead and get the resistors salted to the capacitor read ok the resistors all soldered in I went back and I drilled another hole through this side and brought the resistors leg out into this open trifle there's nothing else in this will be our main attachment point to go to the center conductor I'll coax and what I'm going to do now is drop our geranium doubt with the cathode facing towards ground got us having ears on this particular probe and we'll put it over here and then drop it down to ground through this side so we will have our height and ground or I'll coax separated by the syringe body okay so now as you can see this is our center conductor here and put the doubt on the other side with the anode going to the center conductor then I run the cathode of the doubt out this way then we'll hoof our ground here and I'll Center conductor there and that'll give us good strain relief so we won't pull our coax out sorry about not keeping it in shot just want to see just how it's done and we'll go ahead and get on coax on and for this program we use the small og 174 coax cable it's a lot small wine will work real good so I got my coax separated in this way we can connect the center conductor to the can't voted a doubt and will push the ground way through the other side and I'll connect to the inner to doubt that'll be out ground so as you can see just how basic how simple it is to build a simple already up-close it's real easy to do with most of the time you're gonna have just about all this stuff laying around anyway if not you can run down to the drugstore and pick up one of these syringes or I'd say you know magic marker or whatever and if you do it in a magic marker you can cut you a piece of plastic out throw you some holes in that the mantra components on the slide again or you can just build what's called ugly construction where the components are just soldered to each other and then to the coax cable and the tip and then slide them to your pen holder and then you know hot glue what's real good for securing all that I'm going to take a little bit of superglue and just glue my probe tip in place so it can't move and I'm gonna put just a little dab on the coax back here also and that'll give it a little extra strain relief and you know if you superglue or whatever make sure it's dry before you slide it into your housing so the only other thing we need to do is put off the grounding strap on it to clip to the chassis and I think I'm going to use on this is a little bit of Kim week it makes good good grounding straps I filled one more hole here we can slide this up in the hole and then I can solder that to our ground bus and we'll be good to go on that okay I got do this attach and I will get a clip to the end of our ground and we can take this and just slide it into our syringe body I've took the dremel and I'll me a little tip on the end of it so I can get into a piece of wire whatever I'll put a video teaching that drawing this in and we have a simple RF Pro ready to go okay now that we have all very simple RF probe all put together and we'll be ready to be used for future repairs we'll go ahead and show you how to turn this into a switchable or f AF probe you know like I said this radio noun calls for me to use and RF probe so on the bench I'm going to show you just how to make a a simple little already up rose and while the guy here is a small tube of aluminum about five inches long we have just a plain piece of circuit board there's a switch alligator clip some number fourteen bare wire 47 K resistor crystal diode twenty and thirty four way and it calls for a point zero zero six eight capacitor I do not have one but I have two thirty threes when you pair all of them together that gives you point zero zero six four which will be close enough get a coax cable this is an old tip-off a cheap pair of test leads away I think it was like a seven dollar voltmeter I bought years ago and you know that it was just for some testing purposes and delays or crap but I saved the the tips off them and they don't screw on then you saw her directly into a bit of coaxial cable and I went into Tinkercad and printed these little Ian's here it's about twenty three millimeters on the bottom 26 millimeters around the top of it so uh they fit nicely into the ends of this tube as you can see so what I'm going to do is you're allowed to sum of one of these and drill this end out a little bigger I'm going to take this tip and on my salt on T so this number 14 gauge we're into it and then slide it in and throw it to the end so that the wire will stick out the other side and that will attach to our circuit board now you don't have to get this elaborate when doing this you don't have to make one just like this you may not have a 3d printer to be but get out in hardware store you can pick you up a couple of law magic markers pull the cap off the end or the tip out and snatch the inside out it leaves it you know this is clean inside you think nothing that I have to clean up works very well it will get the job done and save the cap to go by coming in when you drill it out to run your coax out it up or now this RF probe that's gonna be an Oreo a yeah probe so that would be a switch in it well you can mount a small talk will switch right here on the end and just run the coax out the side down here you can pick up some of these at your local drugstore and you can actually build a circuit you don't have to use a circuit board you can just build what we call ugly construction all the parts just soldered in line and take a piece of wire slide it all down in there use some hot glue or epoxy including place shopping into the wire a little bit and when you run your coax out you can use the stopper here just drill a hole through it put it right down here in place and glue it in place and there you go real simple I've always liked the Hibiki style probe so that's why I decided to do this we're not going to off the extra circuit board we just want to use a drill more to cut out the traces that we need very effective works real good so you can see I've got my little circuit board carved out and all I used was just a cut off wheel you know I took my parts I laid them out how they needed to be on the circuit and threw it out on the board how I wanted it to work on a switch the only thing that Swiss does it's shorting input to the output so that the signal when it comes in from the probe passes straight through to the center conductor of the unit and that's for your audio but when you go for all if you have to have the components in line okay I'll draw you look at the diagram with what we're building here this will be our TF will come here with our point 0 0 68 picofarad capacitor our duranium diode in our 47 K resistor and this will go to the center of the plug the ground will be the shield itself so Wendy switch is in this position it is in the RF mode when the switch goes forward and to next these two then it'll be in the audio mode and then harder your motor just goes straight through in the RF mode then your signal will pass through these components and to the center conductor of your coax so we'll go ahead and start mounting the components on here now as you can see here on this point this is where they switch will connect to so it's basically just a complete loop around the whole outside with a couple breaks for the components that go in and deep break when the switches want to be okay so as you can see that's basically all there is to it we have a tip Ian through our zero zero of 68 to compare capacitor come here through our crystal drive throughout 47k resistor then out you back so when I check continuity in the all repetition should be no continuity because it's going through B the circuit wanna switch it to audio we have continuity so that's straight through now I'll get the tip mounted keep it slid into the tube I'll drill out the hole or the switch and the mounting screws and there you go there's all completed or else a rope now what I did was took a piece of flat braid and it soldiers get here to this ground plane that's in the center it's not connected to anything else but I left a little bit sticking my soldered it in the middle and this is so that when it slid on this actually can go in between the case and the outer button that goes on the end and that grounds the case so we'll go ahead and slip this together okay I got the smoke it boy slid in that the switch mounting screws lined up and put the two screws in now all we do is take the little piece just hanging off and just hook it to the side and we'll slide these two through the end adapter it helps if you go back and just tape the end to it can we move the tape and then we sell gray oldest firmly attached and what I'll do I'll drill two little holes on each side and put two little tiny wish cookies on each side of the plug board just to hold the ends in place and there you got one a yeah all right and we didn't put a label on the side of it got our crayon clip-on and we'll be using this in this series of videos for only getting to actually doing some troubleshooting in circuits I just want to show you just how simple it was only total build time on this was just a shade over 30 minutes that's not counting training the in holders but like I say that's other things you can use ballpoint pens I've seen people use those just syringes - magic markers but it's a simple circuit and if you're pretty handy with SMD stuff you can use one of these little small syringe just remove the needle from it you can pull this out and make you a little small circuit board it's best to use a double sided board this way you have your positive on one side and your negative on the other and all you have to do is score the board and mount your SMD parts on it slide it in with your tip coming out you can do it the same way we did the the other one cut it off through your hole through it for your cable to come to us and make some very nice little small pocket size all your pros so we have this realistic htx that's 100 here on the bench that was sent in from a viewer and the story behind this radio that he took it to a he was a teacher at a college he took it in for ham radio show and tail left it there overnight he forgot about it went back to later on pick the radio whoop least it was still there you know it wasn't stolen but for some reason somebody played with it and the radio now it does not work now you could plug the power into this and turn it on and see what it does but again you're not sure what's wrong with it no the information I got on it was very limited someone could have tried to hook it up and hook it up back was blow the reverse polarity off circuit out pushed up again you know keep your powers fire down if your power supply's rated you know so is protected be no problem but if you're using a power pilot it's not very good you know you can end up doing more damage not only could radio but to your power supply so first thing would you just go ahead and open up the radio and we'll take a visual of it all right I have the covers off had he thought of this speaker to get it out of the way and you know the first thing we're going to do is look at the radio and see if there's any thing that's obvious just looks like it's blown you know capacitor blown out or or able to now being that it was just said that it was left there when he picked it up it would not work we have no idea what is wrong with it and the first thing I want to do is look at this reversed protection down that's right here and just left me a corner and to do that we'll turn it over and you can see the red and black wire from the power jack you're going down to the board and we want to make sure that that does has not been compromised we'll get over voltmeter here and look long dows mode and walk across these connectors point 5 volts drop across the dough so as you can see that dude it's not being compromised so it really doesn't look like it was connected backwards so if it was it was on such low current that it did not blow this dies now looking here I'm seeing something else that looks a little strange I can't tell what this is from but you can see this trace here like it's going to it I see that's a buyer I don't know if somebody that's great the solder mask awful he got hot or what happened it doesn't like it was born off and actually looks like somebody scraped it off I just want to test and see if there's any continuity on one end to the other in there yes so you know the mystery continues now I will go ahead and tell you from experience there are two things that causes problems in this radio one is the electrolytic caps the other problem is that brown glue and yes we do have some in here there's more on the back I like to get a hand look real good but yes there is brown clay as you can see it all over the place there in fact it looks to me like this jumper here is starting to cry get on that end next to that glue that stuff is just horrible cuz right the old radius the worse it is [Music] and the more conductive it becomes so after testing that reverse protection does not found any problems they're looking over the radio and see anything that's obvious we can go ahead and power it up and see what it does it does anything go ahead and hook up an external speaker what broke the power into it but the volume down and we'll go ahead and power up the IFR you are 28 megahertz [Music] way down general right single-sideband you know first time [Music] and you hold it for a moment and to receive a faded right out check our settings everything looks okay give the radio a little flex and receive it's not coming back since this we did hear audio to start with and then it just gradually all of a sudden faded out it didn't quit it just went to a fade that tells me that something got hot and once it got hot it shut the audio wall now cut the radio back off and we'll turn it back on when you can read about that here we do have a ton so when this happens first thing you want to do we know that our audio outlets over here in this corner then come through we start looking through here but one best piece of test equipment you got get your fingers I'm hearing just start filling around and I'm looking here but it just faded out again oh yes off it goes so just by doing this few tests what I have found out is that this ice each of them you remember this is the one I told you to head some ma coating scraped off so here this one back here that coating is gone well this IC chip it is running extremely hot but that doesn't mean that the IC chip is bad I mean what do you see around it here lots of capacitors so it's a pretty good chance that if the ready was hooked up backwards on some low amperage it could have took one of these capacitors out or damaged one of these capacitors and it's shorting out the output of that IC chip and so you know again my biggest thought is that these capacitors somewhere in this audio circuit is it's going bad you can see this main kept here thousand microfarad at 25 volts and you can see all this brown grew around it and running right up underneath this audio transformer that can cause all kinds of problems that glues become conductive so we're looking here at our schematic audio output chip to the TDA 1905 well it's the old speaker connection here it comes around and goes through one electrolytic capacitor it comes down here to pin 1 you can see waterfalls pin 1 and pin 3 it's C 103 this is a 47 micro farad at 16 boat cap that would be the forest capacitor that I would think that could cause this to start heating up and go out so looking here at the radio at the back towards us we can see IC 5 here and this is C 103 so I'm gonna head and just remove that we'll take a look at it I've removed that capacitor and we can see it's a 470 UF and they have a 10 volt capacitor installed so we're just gonna go ahead and check it I'm gonna replace all the caps in this radio anyway wanna give it a check and see what we come up with and you see it tried to read the capacitors and all of a sudden it said in circuit leaky when the ESR 0.14 homes so there seems to be something is wrong with this capacitor so I've installed a new 470 micro farad cap in place of the old one hence I've turned the radio on I'm gonna let it sit here and just cook in for a few minutes and monitor it and see our boss our IC chip gets hot so we'll be back in just a minute okay and it's been running for a few minutes probably about 8 or 9 and our IC chip is cold as a cucumber no problems so as you can see one little capacitor has caused this problem in the radio show you the volume control is scratchy - yup like a boat stone and it seems to be receiving just fine now it's possible that someone did hook the Lydia what back was only LuAnn for supply enough what would not blow the divorce protection value but it did get this capacitor and that is possible this is only a 10 volt capacitor I put a 16 volt back in place but I just wanted to show you that sometimes troubleshooting is not that much of a mystery if you think it is it's a lot of just common sense you know I found that the best way to troubleshoot a piece of equipment is to find out what is working instead of finding out what's not working because once you find out everything is working then you can narrow down the components that are not working it makes a little easier so the next thing we know now that receivers working will check the transmitter turn the volume down plug the microphone into it get a cream your indicator will look over at the idea are and all we want to do is see if we have modulation testing one two guess one two and we do you can see the spectrum analyzer rising click and set it to peak power little 15 watts test one two and we're getting plus 15 watts you see the signal light coming on so the transmitter looks real good so the next step in this radio was to go ahead and get all this brown glue removed and replace all the capacitors and she's still running cold no problems whatsoever well guys I hope you found this little tips are useful if you did you know you can leave your comments down below and click on the show more tab to check some other links and stuff out and we'll be coming up with more videos like this here in the future I'll try to run mini series of uh of this episode so stay tuned and we'll see you in the next video

Channel: The Radio Shop

Views: 17,684

Keywords: rf probes, troubleshooting, learn radio repair, ham radio, cb radio, theradioshop, the radio shop, vintage repair, RF, electronics

Id: -02B-EAbbT8

Length: 46min 28sec (2788 seconds)

Published: Sat Jul 21 2018