#127

[@BobGrossAviation]

Peter, Thank you much for these gifts. I never really understood PLL! But after watching your videos I tackled my fathers old Icom IC-728 which has been plagued for years with intermittent cracking receive. I did the alignment and found all voltages and frequencies were off a bit. So amazingly...It works perfectly now! Fantastic. I rewarded myself with a nice bench upgrade by buying an Agilent 34401A and new Rigol Scope! Thank you again.

[@TRXLab]

Hi Bob, glad that the video was helpful and you was able to fix the radio. Have fun with your new stuff..Thanks for stopping by 73

[@4X1000]

Yesterday evening I sat down in my couch, loaded with a thermos of coffee and watched your video which is always a welcome moment. Thanks for one more excellent and interesting video TRX Bench! 73's SM2GXN

[@TRXLab]

Very appreciated! Thanks for watching 73

[@dinosworkshop6870]

An excellent video tutorial. Pete has done many like this so we should have good reference to go back to. We can do repairs and diagnostics without working in the dark. Break out the multimeters and soldering stations!

[@TRXLab]

Thanks for watching. 73

[@phillipvt]

Thank you. Appreciate your work. Lots of respect for your bravery to work on a IC706. Well done.

[@josemiguez2375]

i enjoy very much this video.you turn something so hard like pll circuit in something very easy to understand.thank you Peter

[@TRXLab]

Thanks for the feed-back Jose 73

[@TheRadioShop]

Finally had time to watch this one Peter. Most interesting my friend. PLL is one of my weakest links. So videos like this help a great deal. Hope you get to do another video on PLL's. Thanks for the excellent video.

[@TRXLab]

Glad that you like it Buddy. Yeah from time to time we have PLL issues but very often a missing voltage only. Sometimes a bad cap in the loop filter but this is different. Thanks for watching my friend 73

[@mikesradiorepair]

Great video Peter. Just doing some PLL troubleshooting today myself. I ended up finding two bad ceramic coupling capacitors feeding the tripler transistor.

[@TRXLab]

Thank you Mike, yeah PLL faults can be tricky 73

[@jobluez]

Helped me tremendously in learning your techniques!

[@TRXLab]

Thanks for watching, glad that it was helpful for you 73

[@famossfla]

Wonderful troubleshooting tips. Thanks very much. Really enjoyed.

[@TRXLab]

Thanks for feed-back 73

[@robertrainey1728]

Yes that was interesting Peter. Thank you.

[@roymercer6967]

As usual this was very well done sir. Thank you for taking the time!

[@TRXLab]

Thanks for watching Roy 73

[@notfallmed]

Wie immer klasse danke Peter ein schönes Wochenende.

[@TRXLab]

Vielen Dank Peter, auch für dich ein schönes (Rest)-Wochenende 73

[@injoelsgarage3934]

Peter, awesome video. I learn so much, just a newbie wanting to learn more as each days passes. Thank you for sharing. I'll be back of course. Joel

[@TRXLab]

glad that you like it...Thanks for watching 73

[@eddyane67]

Great video, great troubleshooting lecture! Thanks.

[@TRXLab]

Thanks for watching Eduardo! 73

[@JamesP6084]

Very interesting as usual Peter look forward to second part 73's

[@TRXLab]

Thank you Jim 73

[@TheDefpom]

I would try injecting the 9.01mhz signal that the ic provided to see if you can get the PLL to function, and then go from there.

[@WN8HGZ]

Thanks for the technical explanation of PLL it was very very good from Wb8idy in the states

[@TRXLab]

Thanks for feed-back Brian. It is a honer to get this nice grading from a professional like you are! All the best and 73

[@vex9060]

Cheers Peter! Good tutorial. Usually I use a preheat element on the other side of the board for example at 110 degree C. 73s LZ1MOB

[@TRXLab]

Hi Mihail, yes a preheater is differnt way to do it. I prefer the method of carefully heating the pcb up with 300°C and than increasing the temp and going down to the ic.. Thanks for watching 73

[@adnanmalik7364]

you are par excellence !!! well done !!!

[@TRXLab]

Thank you Adnan 73

[@vintagecomputers5340]

Thank you for this excellent video. I’m troubleshooting a sick ic-706mkiig with no 1st LO. The ref PLL checks fine with all signals present. I’ve isolated the problem to the main loop PLL with no signal at the output of the VCOs (Q10). I’m suspicious of IC461 but can’t access it or the VCOs since they are located on the backside of the PLL board. Noticed you have extra long ribbon cables that might help. Can you please tell me where you obtained them? Maybe provide the part numbers. Thanks again for your great videos!

[@DeadQuirky]

Aliexpress?

[@TheDefpom]

I was planned for on doing a PLL theory video too, you kind of beat me to it ! I will still do one anyway as mine will be more focused on CB radios.

[@mikesradiorepair]

TheDefpom At some point I am going to do one to. Got a parts radio here tha has a separate synthesizer module in it that works out of radio. Its old school 4000 and 7400 series TTL and CMOS. Figured that would be nice to use so I can demonstrate individual circuit functions. Hard for some people to understand all the circuits used in single chip PLL's.

[@TheDefpom]

MikesRadioRepair - I guess there will be an influx of PLL theory then ! Between the 3 of us we should have it covered from all sides 😃

[@mikesradiorepair]

TheDefpom The more the better. :)

[@TRXLab]

There are so many additional aspects around the PLL which are not covered in this video so much more to do for all of us :-)

[@WN8HGZ]

Very well done thanks for taking the time to do this brian Wb8idy usa

[@adrianclark9581]

Fantastic with explanations

[@TRXLab]

Thank you

[@bundylovess]

NICE VIDEO PETER BIG THUMBS UP MATE

[@TRXLab]

Thank you Allan 73

[@joepereira3421]

Great explanation Peter enjoyed watching. Is it possible for have a second camera looking at your instrument meters that way you need to keep re-positioning all the time?

[@TRXLab]

Yeah a second cam would be nice but this video production is a one man show and it is additional to my normal workload..73

[@dennisqwertyuiop]

great work, how much would new board cost or maybe no longer made

[@TRXLab]

Thank you Dennis. Well the board is approximate around 250 bucks...73

[@herbertsusmann986]

Good video Peter! Almost seems like the +5v went too high at some point. Maybe the 5v regulator failed, other guy replaced it but radio still didn't work so he gave up?? If so, could be other ICs are now bad as well.

[@TRXLab]

Hi Herbert, may be but the owner don't know. The last visit before it came to me was ICOM Europe. So all is a bit odd. Thanks for watching 73

[@majordisappointment8692]

Yes nice video very much appreciated thanks for the info.

[@TRXLab]

Thank You 73

[@iw0hex]

Great video Peter, let us know about this repair.... 73s Pasquale IW0HEX

[@TRXLab]

Thank you Pasquale.. Cheers and 73

[@Beretta96Dan]

Thanks, Peter. Looking forward to the next video on this repair (if there is one). The owner will just have to bite the bullet and have you fix it. 73...Dan w4mnc

[@TRXLab]

LOL yeah he really has to bite the bullet..Thanks for watching 73

[@PapasDino]

TNX Peter, learned a lot. Hopefully we'll see how this one plays out. 73 - Dino KL0S

[@TRXLab]

Thank you Dino, glad that it was of any help for you! 73

[@glenwoofit]

Inject the DDS frequency from a signal generator directly into the PLL and see if it locks.

[@TRXLab]

as long the shorted dds is not back in place I have still the unlock. so that is the second step. 73

[@davidgaleski5303]

thank you for the Help

[@TRXLab]

Thanks for watching David 73

[@magjagmagjag]

At last, was the ic real culprit for pll malfunctioning? Yr step by step guide very thorough n indeed helpful, thanks alot...

[@tlrptg]

please make a "part two" video in case your client decides that he wants this radio to be fixed.

[@TRXLab]

If the owner deicide for a repair I will do. Thanks for watching 73

[@petrok1rp254]

I have different symptoms: RX somehow work but no selectivity, CW signals has all splatters through band and it is changing after TX/RX switching. Looks like on TX it works. Could it be also PLL issue please?

[@petrok1rp254]

Even more …all CW stations has no tone in audio just keyed noise…

[@georgetzanakis6041]

Hello i have an icom ic-f310 with a Flashing screen Same situation as the YAESU video.is it possible the Same problem?

[@davidgaleski5303]

thank you

[@TRXLab]

Thanks for watching David 73

[@bigfoottoo2841]

Use the schematic more to guide you. look at the function of the two 220 resistors and the 7805. Most likely, at some point the 5 volt supply went high to the input voltage of the 7805 and cooked the chip. What is the voltage into the 7805?.

[@TRXLab]

If I would have guessed that an over voltage occurred to the radio I would have mentioned it. The voltage regulator is directly connected to the switched 13,7V line. If we would have had an over voltage to the input we also would have had an over voltage to other components i.e. on the main board and not only this voltage regulator would have been toasted...

[@bigfoottoo2841]

What I am saying is that at some point the 5 volts went to 13.8 volts on that board. If you will notice, resistors R291 and R292 have both been replaced, they supply power to the 7805 regulator chip. The schematic indicates they should both be 22 ohms not 220, unless of course the 0 means zero zeros. The 7805 has probably been replaced as well, . Also note that 2 chips have failed supply chokes, one open and one at a high resistance. High current has gone through both inductors, it is very unlikely that both chips had internal failure at the same time. A voltage higher than 5 volts has been applied to both of them. It is very rare for a 7805 to short and allow its input voltage to show up at its output, but if it got hit with a high enough transient, it might. However, such a high transient would have destroyed a lot of the radio, maybe it has. if 13.8 volts is applied to the output of the 7805 without 13.8 volts on its input, it will smoke. Consider the possibility that someone may have applied 13.8 volts to one of the accessory jacks on the back allowing it to somehow get to the 5 volts on the PLL board.

[@alessandrozax]

Not easy concept this time, but good video as usual...at 34:40, for some seconds, we have lost the upper side explanation of your camera :( -- By the way, we are waiting for the next episode. Let us know. -- '73

[@TRXLab]

Yeah bad came positioning..sorry for that but it is not much missing. Thanks for watching 73

[@alessandrozax]

you're wellcome.. :D

[@mrcina22222]

Not tuner TX signal....IC737A....👌👌

[@rlmillr]

but my screwdriver really is golden :) Great video

[@TRXLab]

LOL ah you are the one :^) Thanks for watching 73

[@dewaynepark]

Focal

[@davidgaleski5303]

trying to be hamradio 61 yrs old machinist

[@TRXLab]

Hm not sure I understand what you mean David 73

[@davidgaleski5303]

i'm trying hamradio

[@TRXLab]

Ah okay you will manage it no problem 73

[@harbselectronicslab3551]

You just need to push the Lock button on the front of the radio...............lol

[@TRXLab]

LOL yeah not recognised the button..

[@gvvq-pi5ml]

I'd fit a new board Peter.....Fred g4vvq.

[@TRXLab]

Let's see what the owner is going to do.. 73

[@GiorgioFirpo_IU1BKT]

Golden screw driver hit again :) .....

[@TRXLab]

yeah the golden screw driver never disappear lol Thanks for watching 73

[@DeeegerD]

With all respect - your videos are too long. I look and see a video that takes over an hour and I think "I don't have time for this." Not only that but one gets bored after 20 minutes or so.

[@vintagecomputers5340]

Thank you for this excellent video. I’m troubleshooting a sick ic-706mkiig with no 1st LO. The ref PLL checks fine with all signals present. I’ve isolated the problem to the main loop PLL with no signal at the output of the VCOs (Q10). I’m suspicious of IC461 but can’t access it or the VCOs since they are located on the backside of the PLL board. Noticed you have extra long ribbon cables that might help. Can you please tell me where you obtained them? Maybe provide the part numbers. Thanks again for your great videos!