CALLING ALL ELECTRONICS EXPERTS!!! Help Me Fix My Amplifier!! Mirage D1010 UHF Amplifier Repair..

[@mikesradiorepair]

DO NOT go throwing a bunch of parts at it as many have suggested. You will most likely be replacing a bunch of parts there is nothing wrong with. Troubleshoot the problem. The first thing suspect to me is the no power on LED light. Trace through the power supply circuit with your voltmeter. Loading a bunch of parts a 12Ga shotgun and blasting them into the amplifier will likely not fix it. Looking at the schematic I could quickly find using Google. If the power on LED isn't coming on I wouldn't even bother looking on the RF board yet. Check for voltage at the on/off switch and that you have power out of the on/off switch when you turn it on. Next would be the thermal protection switch which is connected to the "out" side of the power switch. If you don't have power on both sides of the thermal protection switch with the on/off switch turned on then it's probably a bad thermal protection switch. The power on LED is connected to the opposite side of the thermal switch through a current limit resistor so if the on LED isn't coming on I would suspect it's a bad 170deg C thermal switch. If that thermal protection switch is bad it will not turn on. Having now watched to the end of the video it looks like you saw the power on LED light up. Possibly a intermittent connection. You should still start tracing the power rail from the power switch. There are only a couple things that could prevent the power on LED from coming on as I described above. Mike KC3OSD

[@VintageElectronicsGeek]

Mike - When you coming back? I miss your videos!! You are top notch ! I refere to your videos often. :) ~Jack, VEG

[@johnathanasiou9284]

Omg Mike hope you've been really great & thanks so much for lending your expertise to help Eric out. 73s!

[@Nathan1975Liggy]

First thing I would do is reflow all solder points. Second thing if resoldering does not work is to replace all the electrolitic caps.

[@dwoaks1]

The big diode is for polarity protection if the B+ & Negative are connected in reverse. To cause the fuse to blow and protect the amplifier.

[@markusberg2770]

According to the associated schematic, the molex plug on the backside is for an optional Remote Control Plug. Apparently, the default of the plug is set to Remote on Pin 1. Pin 2 is 13.8. volts. Connecting power in a jumped scenario may turn the unit on. Essentially, similar to the SignaLink that has internal jumpers for complete functionality. You will find the schematic when looking for the ATV capacitor modifications on the Mirage finals. 73 from Volusia County

[@neal_laugman]

Looks like a COR (carrier operated relay ) circuit. Nothing will happen until a carrier is detected from the transceiver. Build yourself a diode rf probe for your meter to track the rf. NL7VL

[@peterrock2838]

Mr Carlson has an awesome channel, as do you!

[@jptucsonaz8503]

Ok; first things first. Disconnect all power, cables, etc. Electronics troubleshooting 101: VISUAL INSPECTION! grab your glasses (if needed), magnifying glass & a 4x/8x Lupe. Check mechanical connections; i.e. ground & chassis lugs & screws, connectors in place (pushed in all the way) - pins of those connectors not pushed out of place, etc. Next, because of what you have found when you probed that one area; grab your high power Lupe & look at all of the solder joints. Look for cold joints; joints that look soldered but may have a tiny space between the lead and pad, cracked joints (look like a annular ring or rough edge, etc. Now, look AT the traces; looks for splits, lifted or burnt spots or even micro cracks. See, when you pushed your probe down; it may have slightly twisted the board to remake a broken contact. You should FIND the cause first, not just hit everything with solder... Yet! You don't want to lose/hide the problem's cause. If you find the cause, then fix it; you've learned HOW to troubleshoot the problem. Then you truly can fix the problem. Part 2; if you can't find anything visually, move back to GENTLY putting pressure on the board (while connected as before) with a non-conductive probe - wood, plastic. See if you can repeat the former temporary switch power light on. If you cannot, try that probe you first used. It is possible you either injected a slight resistance or capacitance that the unit needed. That would seem to indicate a component out of spec., etc. At this point you will need & share a copy of the unit's schematic to logically proceed; as there's no detail from the video to see how the circuit operates. Give those preliminaries a try & see what you find. Good luck, hope you find the issue soon.

[@HamRadioConcepts]

Cool thank you so much for all your time typing that friend... I'm gonna go through just as you said... I'll post what I do or don't find..

[@Lazyonics]

Don't you just love it when someone asks for help and you get the knackers who just want to tell you how smart they think THEY are (thevenin's theorem LOL ) Anyway, If things are happening as you probe around I would start from a mechanical aspect. Try wiggling wires for an intermittent O/C or go around the board with freezer spray first.... 73

[@thomasperina2990]

The most brilliant mind with regards to rf amplifiers is BBI AMPS LOCATED IN IDAHO. HE HAS MANY U TUBE VIDEOS, TMP FROM N.J.

[@HamRadioConcepts]

Yes I am familiar with him, he's a maniac lol

[@HamRadioConcepts]

Lots of knowledge there in his head

[@mattghoward]

the small capacitors are parasitic suppression and yes you need to put them pack exactly where they came from

[@markarmstrong-noaafederal6442]

See if the power supply circuit is giving you power to the rest of the amplifier. I always thoroughly check the outputs from the power supply first when something doesn't want to turn on, both loaded and unloaded, as something might be drawing down or impeding power from one of the legs. I know you said you had power to the PA(Push Pull amp or Power Amp). Unfortunately, that doesn't mean you have power going to the rest of the Amplifier. You should eliminate the power supply as the cause of the problem before you go down any other rabbit holes. PA's usually have their own leg out of the power supply circuit not connected to the rest of the outputs from the Power Supply. A lot of times in a power supply circuit you'll find electrolytic capacitors that are bad. Bad capacitors in a power supply can definitely cause your symptoms. Good Luck.

[@JAMES-dv1yg]

Like Mike S, Said, Finals Transistors, See How It Goes And You Do At Replacing Them...

[@DeltaXray444]

The very first thing if you cannot or do not have a schematic diagram for the linear i would suggest taking some close up photos of the circuit board before rearranging or swapping parts on the board.

[@HamRadioConcepts]

Good advice thank you

[@jonathancotner7040]

Tottally sounds like a bad/cracked solder joint. Go through and re-flow the joints, particularly around the ground. That's not uncommon in those as they're used in high vibration environments.

[@HamRadioConcepts]

Thank you I will check that

[@nicknitro4420]

@@HamRadioConcepts That's probably all high temperature solder in that unit...

[@KE5ZZO]

So 239 by red power in. Why does it appear white wire solder to center pin and ground tab

[@johnathanasiou9284]

Eric, that the power LED is not always on & only came on when you pressed your leads down is telling & a huge clue of the fault that your DC voltage supply feed into the amp is most likely having problems, or, there are cold/fractured solder joints on the board. If you were having shorted final MRF transistors then your power supply would show a huge current draw & your DC voltage would fall quite dramatically. If you have say a 30v 5A bench supply with both voltage & current meters, try hooking it up to that to check any parasitic current draw. I'd definitely first trace out the power supply feeds first and verify its all feeding DC power OK from the switch and into the amp before looking at anything else. Definitely also check the thermal fuse as it shouldn't be open circuit and you should be able to trace the 12v through it as Mike below had wisely suggested as it should only open on a high thermal temperature condition but provide continuous continuity otherwise. Also, buzz out the wiring for continuity with a DMM. Next, as long as you can verify DC voltages are first OK check the DC voltages on the base, emitter and collector of the MRF648. I wouldn't go pulling out the MRF final transistors just yet until input DC power is being supplied OK is being properly supplied & you are 100% correct they are a matched pair and have adjusted bias via resistors or a potentiometer. Those black hex screw things look like either mounting screws or less likely, some sort of trimmer capacitors but my guess is they are black hex mounting screws as I see the MRF648 datasheet has screw mount tabs. Yeah, trying to diode check the MRF finals might give false readings due to those low value resistors which seem to be 10R to 100R but its hard to make out the values but if you get 0.2 Ohms or something super low beware as it could be the transformer winding tricking you. Some might suggest changing the axial electrolytics (if so, pick equal or larger voltage, same or better temperature and good quality like Nichicon, Chemicon from Digikey) but let's first resolve your DC voltage supply issues first before we go down such paths as if there isn't any DC voltage to bias the amp, you're much like a rowboat with no oars. Looks like a UHF amp design with the microstripline inductors. Ou, the fun of RF voodoo design at those VHF/UHF ranges :) & so surprised that RF stuff like this isn't a genre on PornHub yet. Above all, get rid of those negative thoughts as electronics is always a learning curve & if you never take the plunge to try get into something like this, you'll miss out on valuable electronics knowledge & through hole stuff is far easier than tiny SMD components. If you never give it a go, you will never ever learn & you know more than you realise so lose that fear. If you want to learn more about these sorts of things most definitely check out Mike at MikesRadioRepair & Peter at TRX Lab as they are absolute guns at fixing radios and amps like this & you will definitely gain huge amounts of knowledge as they are fantastic teachers

[@neal_laugman]

As a field and manufacturing tech of many years, 80-90% is all problems are mechanical (connections). The semiconductors should be your last choice. However, with amplifiers, finals and drivers are another story.

[@HamRadioConcepts]

And I always assume finals, thank you for the consideration

[@stevegorecki4512]

Two pots near each other are for bias, don't touch those unless replacing transistors. MRF644 should have about 50-100ma Ic (value varies between manuals) and finals should be 100-200ma Ic (collector current). I think the higher values are for the ATV model (more linear?) Single pot on other side is SSB delay. If relay is not engaging with 5W RF input, check the two diodes (1N6263) and the Darlington transistor (MPSA13) near front, side, near delay pot.. That is the relay trigger circuit. Big diode in middle is for reverse polarity protection. Big black thing in middle is thermal protection cutoff. Opens if too hot, removes DC voltage. That big resistor from finals output to ground is a 50 ohm 10W wirewound which I suspect is more for spike suppression than anything else (connects to antenna when in TX mode). Has enough inductance to not affect RF. Other two large diodes are forward voltage drop to provide about 1V for bias circuits. Good luck, I have a dead D1010 unit as well...

[@stevegorecki4512]

PS: The small chip capacitors around each transistor are required to prevent oscillations. You need them (4 per transistor)

[@eddieMurphy11111]

if you key up with a dummy load on and touch the finals if they are hot then should be ok if they are cold then they are gone

[@sorinelectronics]

I think you should focus following the ground, i can't see a solid ground wire to the input board, the one with the relay. So, my theory is, the amplifer was connected wrong to a power supply, from the plus red wire you have a fuse and after a diode connected to ground, i believe the diode did the job and protected the amplifier, but, from what i can see, from the minus of the diode you have a big resistor, i believe that's the minus passing from one board to the other, that one must be checked. that big 50ohms/5w resistor

[@mattghoward]

to test the MRF you need to remove them - you can do a basic test with a multimeter - plenty of youtube content on how to test a transistor this way

[@Bones469]

I agree with you in that I think even if the finals were blown you should still see the power light or hear the relay. If the back final section took enough amperage to drop the voltage for no power light, it would easily pop that fuse. The same goes for the reverse polarity protection diode, usually when they are "spiked" they henceforth create a dead short to ground taking out any new fuse you use to replace the burnt one. Long story short, my guess is the first problem will be in that front circuitry, while the finals could be bad too, my first suspicion would be in the CAR carrier activated/operated relay and/or power relay and, any transistors used for switching the relay. The relay looks pretty beefy. Is it only used for the CAR? Or might it also switch the power as well? Is it marked? Can you tell which pins are for the coil(s)? If so own out the coils. Also if you have voltage at the switch where does it go? Is it in line with coils of the relay? Now even that can be complicated, I know on many occasions on my homebrew projects I like my switches to merely provide a ground path for the coils. That way if a wire shorts to ground, instead of taking fuses or smoking wires it merely energizes the relay coil. Anyway try to figure out if that relay only has one coil and switch set, then look at the NC and NO normally closed and open pins. Also as others mentioned get access to the other side and look for cold solder. They can be a PITA to identify so get creative and ohm things out, just remember other components in the circuit can throw off the ohm meter. Looks like a fun project. If I lived nearby I would love to peek at it. Also see if you can get BBI to comment. I know he focuses on 11M but the dude is sharp as a tack. Also Big Clive likes mysteries as well and when it comes to mystery circuits he has a 6th sense.

[@Bones469]

Mr. BBI kzbin.info

[@Bones469]

Big Clive kzbin.info

[@redstook]

Where did you find the schematic?

[@HamRadioConcepts]

One guy had one on some website I have to remember where

[@TRIPPLEJAY00]

I have no idea, however I'm going to guess it's the flux capacitor 😁✌️

[@HamRadioConcepts]

It was the canuter valve next to the flipflop transducer match

[@DonDegidio]

Hi Eric, I noticed a Molex connector on the back plate. Do you know if this amp uses a remote? Might be as simple as not having everything to operate the amp. Stay safe. 73 WJ3U

[@HamRadioConcepts]

That's for a remote head and normally in the past when I have had these amps that didn't matter

[@richarde735]

the tubes are missing 😲

[@HamRadioConcepts]

I know.. these damn solid state devices these days LOL

[@gmanshackshack6822]

Replace all those electrolytic caps as a matter of course.

[@viralsheddingzombie5324]

Adjust the valve timing.

[@HamRadioConcepts]

I already threw a new cam in.

[@ElectronicsDoctor-vl4tm]

First off get a Isolation Transformer, Secondly test Power supply separately from output section - Edwards Electronics

[@Sky1]

You are not testing in order. You are not ready to test the finals yet. If you connect a radio and antenna to it WITHOUT power applied do you have a decent vSWR? If not you probably have a bad relay that needs to replaced first common problem, Get them at RF parts. Cancel Save

[@ya837]

Sorry to bother you but possibly the problem is the final transistors or the relay. Both parts are imposible to get here in Europe. Perhaps you can found it in USA but not for long time. These amplifiers are in extinction because changes in RF technology makes parts obsolete. You cannot get them no more.

[@401ksolar]

You're on the right track starting with the power cord however a prerequisite would be to look up the manufacturer of your semiconductors and look for sample circuits in their white papers, then you get an understanding for the platform that it's built on, if you are able to get a schematic and or Tech bench manual that will give you some test points and procedural points, sorry to say it but it takes a lot of study to really understand it, there's a theorem called thevenin's theorem it is where you break down any circuit into three pieces the power source, the circuit path, and the load. Once you are able to overview a circuit in this manner you will have a very good overview of the electronics you are working on.

[@HamRadioConcepts]

Now I got to look that up, thank you for the knowledge friend!

[@401ksolar]

@@garrysekelli6776 you are joking, right?

[@mr.stonerUDX714]

Call BBI

[@HamRadioConcepts]

Oh dude that guy is insane with those amps he builds lol

[@AdamDeal-KF0PRI]

sounds to me you have a bad ground!

[@HamRadioConcepts]

Second one to say that. I will definitely check thank you

[@AdamDeal-KF0PRI]

your welcome! going by what you said about testing over on the ground side of the board and the light come on tells alot! check your ground traces first and that janky looking jump wire from borad to board " the brown wire"!

[@markharrison1160]

IRL current is from the negative side to the positive. Engineers won't change because they learned the incorrect way and go the math is easier.

[@jonathancotner7040]

the flow of electrons is from the negative to the positive. Conventional current is from positive to negative. It has little to do with math, and a lot to do with getting the polarity right when it really matters.

[@redstook]

@@jonathancotner7040 And then when you introduce pn junctions you also have diffusion and drift currents that you need to worry about.

[@offgridwoodworld]

Start by replacing all of those ceramic capacitors, if it still doesn't work after that you may need to add a hyper dimensional resonator

[@HamRadioConcepts]

Lol

[@SP6QKX]

[@leo2395]

Greetings from Croatia Eric! I watch TRX Bench here on youtube, a great, smart guy making detailed radio repair videos, check him out. Do you maybe have any schematics of the amplifier? I would not call myself an expert, just want to see if I could help. 73's de 9A3LET

[@HamRadioConcepts]

I'll have to find them on my PC and send them to you or perhaps part two I can show it if lots of people want to see them