Troubleshooting a radio is a form of craftsmanship! When you at least diagnose the problem you get a sense of accomplishment that you have actually done something, no matter what the outcome. 73

Also, check the CPU reset pin as well as clock pin. Good luck.

Lighting or any over voltage experiences on yaesu radios tend to blow the processor. At least that is what I have found. Thank you for the video

It's still a good video. You don't have to fix something to make something good. I have an old Icom 730 that I found in a camper trailer. It receives great, 100 W TX power, but it squeals like a pig if you listen to it with another radio. I opened it up and it was filthy inside. Dirt/poor ground contacts can raise hell. I tore it all apart and cleaned everything with alcohol. It still squeals. Someday when there's nothing else better to do, maybe I'll figure out why. Ham radio is about the hobby, having fun, fiddling with things and sometimes things can be fixed, sometimes not.

Great video Rob!

Thanks for your help with this

Interesting stuff, even though it's not fixed. Thanks!!!

The video was very entertaining and oh by the way I did learn a little something about trouble shooting as well, thanks for the information.

Thanks for all your great video's Rob!Everything from Ham radio to the Pontiac Vibe Maintenance video's.Love your channel!!!

@SevenFortyOne

9 ай бұрын

thanks for letting me know! Its good to know people like the variety...I'd get bored sticking to one thing all the time

Make sure the CPU is not being held in reset. Power on reset ckt might be bad. Bad cap or something! Thanks for the vid. 73, Mike

@SevenFortyOne

9 ай бұрын

hmmmm....I'll have to go back and look at that circuit

Great video as always. It gave me some ideas to look at on an Radio Shack HTX-204 I'm working on that won't turn on either. (Trying to find an HTX-204 schematic, but seems impossible.) Informative video, thank you!!

An interesting video Rob, I own one of these and an FTM 3207D both good little radio's, 73's G1KEK

I would look at that mosfet and the driver transistor. Mosfets are sensitive to over voltages. These electronic switches can be a pain. I have had several Kenwood that had a similar issue and it was always the mosfet that fed the rest of the power regulators on the main board. We knew that with one customer who came in with a "no power on " issue to just replace this mosfet. Turns out he was improperly jumpstarting other trucks without removing the radio fuse on the battery. He learned an expensive lesson. I had issues with an Alinco switch mode power supply, would not turn on. Turns out it was an open resistor that was part of the "keep alive" circuit. Yes it has a hard switch that cuts power to the whole supply but wen you turn it on there is a small voltage that is sent to the main circuit that allows the supply to turn on. Replacing the resistor brought it back to life. Next issue with this supply was that the voltage would go whacky and drop out and come back on randomly. Turns out it has a small switch on the back that selects variable or set output. It was dirty, a shot of DeOxit cured the issue.

@SevenFortyOne

9 ай бұрын

After putting this aside and talking with a few others, I agree...I need another look at that mosfet

Thanks so much for the video Rob!! I loved it and learned a lot. I wish more folks made videos like this!! Robert K5TPC

@SevenFortyOne

9 ай бұрын

I'm glad you liked it!

I would have shorted pins 4 & 6 of Q1003 to see if Q1003 had failed. The fact that the radio did start up gives me hope that the u-procesor is still good.

@SevenFortyOne

6 ай бұрын

Good point...I need to revisit this radio again and see if that will work

Great video Rob Such a nice radio and chassis to have to shelf , might be worth at least the diagnosis fee if you have a trustworthy tech/shop within a 30 minute drive 🤷🏼‍♂️ 73’s

those big connector, sometime, it is easier to add low melting temperature solder , though mixing it with existing normal solder, that will bring melting temperature down to 140 degree C or so. AG6JU

Hi Rob, You had a good go at sleuthing. I'm afraid your conclusion about the processor may be correct. Was hoping to get you earlier when you QRT'ed to 20M at Nye Holman State Forest. Just finished getting my new ALS-606S connected and ready to go. Stay safe. 73 WJ3U

@SevenFortyOne

9 ай бұрын

Sorry I missed you - I had to get back to work so I cut things short. I might be on next week around lunchtime so keep an eye out for me...

👍

The multi-layer boards have very thin traces in the boards, if there is any defect at all it's easy to see how the constant board flexing from normal heating/cooling could make the trace sketchy.

@SevenFortyOne

9 ай бұрын

Good point. I'm more suspicious of the plated via holes though. The barrel plating can develop cracks from thermal cycling and cause opens.

@mscir

9 ай бұрын

@@SevenFortyOne Can they be reflowed and filled w/solder to repair that?

@SevenFortyOne

9 ай бұрын

@@mscir that might be doable if the vias are big enough to allow solder to flow through them. But not reflowed - you'd have to add solder as there is none in the vias now - they are just copper/gold plated.

Rob, I'm guessing that the P-channel MOSFET (Q1003) is most likely damaged. Think of Q1003 & Q1006 along with their associated passives as a solid-state relay with the "contacts" being the SOURCE & DRAIN on Q1003 while the "coil" input is the BASE of Q1006 and GND. Rather than trying to switch on this "solid-state relay", simply jumper across its "contacts" by connecting a short jumper (use a small resistor lead) across SOURCE & DRAIN of Q1003 (see on the schematic where Q1003 / RTQ030P02 is printed, the jumper would be a vertical line running through the letter "R" thus jumpering the MOSFET's source and drain leads). If everything powers-up, then there's a very high likelihood that either Q1003 or Q1006 is shot. My money is on Q1003. BTW, directly injecting VCC (your last step of connecting 3.2v to the BASE of Q1006) can cause problems to "upstream" drivers especially if they're driven output devices (i.e. totem-pole output) as opposed to open-collector outputs. In your case this would have been MCU I/O (pin #87 - Reg_sw) fortunately the current-limiting resistor R1032 probably saved your bacon. In the future, when trying something similar, put some resistance in series with the jumper to limit current flow that can damage a driven I/O port. Good luck and let us know if you successfully bring the beast back to life.

@SevenFortyOne

9 ай бұрын

I should have thought about just jumping the source and drain pins...not sure why I didn't think of that. I'll give that a try when I have some time to check the radio again. Thanks for the tips!

Super weird that it turned on once and won't again... I would say the CPU is still good. If it turns on once and seems to work, which having a display and it's memory, means that it's probably still good. Did you check to make sure that the CPU is actually getting power on all the pins it needs power to? Jumpering it like that may have bypassed a short or a bad voltage somewhere else.

@SevenFortyOne

9 ай бұрын

I did some more digging I didn't show in the video but I thought the same thing as you. Although when it came on that one time it wasn't right after I jumped the regulator circuit it was later. I didn't show it in the video but I also tried freezing the radio to see if maybe that would do anything...it didn't. But I'm not ruling out a bad solder joint someplace.

@dacodemonk

9 ай бұрын

@@SevenFortyOne definitely keep us updated on this one!

What about the fuse at 3.38 minutes into your video , extreme left on the schematic about 2/3rds of the way up , that would be the first thing I would check

@SevenFortyOne

3 ай бұрын

I don't have the schematic in front of me but I think That fuse is only for the USB power so even if it was bad it wouldn't prevent the radio from turning on

The MOSFET is more likely to fail than the CPU. And if that's true, then the voltage isn't getting to the CPU.

Charge the fuse....

@SevenFortyOne

9 ай бұрын

There is no fuse

Every Yaesu radio that I have owned and failed has been the microprocessor, AND they no longer supported that processor... Go figure!