#258

[@russramirez5672]

Hey Alan, great timing as I just picked one of these up a month ago with 144, 220, and 430. Has both issues, but one meter bulb is still good. 45 years of fixing rigs and I still love it! Russ, K0WFS

[@ufohunter3688]

My LG 42" Plasma TV had the same problem. Mine kept shutting down randomly. Changed some of the caps to 105 ºC and it works to this date. I am not familiar with Transceivers, but I was told that SMPS's should not be used, as they produce to much noise and one would require a lot of complicated filtering to get rid of the switching noise!? Also, there was something wrong with the play back of this video! I let it buffer, then replayed those portions with the same effect. I really like your channel. Thanks for uploading your work for us to enjoy and learn from.

[@w2aew]

Switching power supplys *can* be noisy, but can also be properly designed to be reasonably quiet from an RF standpoint. It helps that this rig is VHF/UHF, since most switchers create noise in HF bands. I think KZbin messed up the rendering. My .mp4 file that I uploaded plays fine.

[@ufohunter3688]

10-4 thanks

[@MrRoyzalis]

Thanks for editing your videos so they are concise. I would guess it takes a lot of time on your part to do so, but it is respectful of your viewers.

[@w2aew]

Thank you for saying so. I try to keep my videos to 10 or 15 minutes maximum. Ideally, I'd make them 5 minutes long, but most of my topics require a little more time. Many people don't realize that creating condensed content like this takes a long time - usually 10 to 30 minutes per published minute of video, if you take into account all of the preparation, experimentation, research, shooting, editing, etc.

[@RadioHamGuy]

Another great video, always good to see a good old radio kept alive! 73

[@MichaelLloyd]

I think I enjoy watching a successful repair as much as I enjoy doing one. I noticed an HP calculator in the background. Actually I could have just said calculator... if it's not RPN then it's nothing more than an abacus or box of toothpicks :o) I always enjoy your videos. Thanks for taking the time to make them

[@yenaurapourtoulmonde]

I changed the two resistors for bigger ceramic 5 W resistors, mounted far apart from the PCB and the capacitors (used in fact all the available wire length). One more thing : check DL7VHF's improvement with one fan to cool the said resistors, where I glued a 40 mm fan on the PCB to the right side the 33 Ohms resistors . There are two unused holes in the PCB, and once the solder removed can become convenient connection for this 12 V fan. When remounting the grill over the power supply, you'll have to file the 3/4 of the right tab that comes in conflict with the glued fan. Plus even a second one 22 mm fan located just between the power transistor Tr4 and the two power resistors on the left, tied with a collar to the two U shaped heat sinks. Its connection is picked at the location of R21, which I displaced on the solder side. Maybe I will use in the near future, as an improvement, thermistors to avoid the slight but annoying fan fizz, so than to reduce spinning speed when not needed. DL7VHF also increased the values of the capacitors. In my case I used for C21 and 22: 3300 uF / 25 V and for C26 1000 uF / 35 V.

[@w9gb]

Alan - Remember to check the lithium coin cell. Located on front panel control board. Replacement is Panasonic CR-2032/VCN (Digi-Key $1.11), vertical, solder-tab (VCN) style. Yaesu used Sony for their OEM battery supplier in 1980s. I change this lithium battery, when changing the incandescent bulbs (S-meter): Yaesu: BQ041-228038V 100 mA, 8 Volt Lamp. greg, w9gb

[@w2aew]

Good point about the battery.

[@rb28845309]

Hey Alan. My radio looks really nice sitting on your bench. At one time I thought about fixing the power supply in mine! But been running it on an external supply now for years since being disabled! I used to work on all the amateur radios when i had a shop. But can't hold a soldering iron anymore. Thanks for the great video tho.....Ron

[@rb28845309]

Hi Alan. So I made an attempt with my crippled hands to replace all the caps you meantioned in your video. Bought all the caps thru Mouser Electronics. Radio lasted about 5 days working great. Then out again. I used all the specs when ordering the caps. Don't know why it went back out. So back to the external supply again. Too much work for me being crippled in my hands. Won't try it again. Seems others are having good luck tho.

[@powerelectronicsguyl306]

If meter backlighting is another common problem it still would be nice to see your led replacement design. i would think matching up lamp bodies and beam dispersion would be the challange.

[@Geoffrey7b]

Alan, one of the suggested mods to permanently resolve the issue was to add a small CPU fan to the cage to cool the hot spot down. There even seems to be a pair of open holes on the board for exactly that reason. Interestingly, there is also a DROK PS unit that will fit into this space if the original PS cannot be rescued. I went that route myself for mine. If one goes that route you will need to put 4 new holes in the metal sub-chassis to attach it securely, but it fits just fine inside the perforated cage. The '736 is a really great radio, and I'm impressed a rig of this vintage has quite a few SMD components in it-- very cutting edge for that time. -KA1IOR

[@w2aew]

I've see the fan mod. The rig's owner wanted it "stock", so I didn't do that mod.

[@chrisstorm7704]

The previous owner of my 736R found a NOS power supply to put in, but decided to no longer use the integrated supply to power the rig because he didn’t want the new supply to suffer the same fate as the old one. So now I have a radio with a virtually unused supply in it, but I keep using an external supply myself because I’m worried that the caps have now degraded from being powered off for so many years. I used to think about recapping or starting the supply on a variac, but once the radio was connected to the shack supply, I quickly forgot about the internal switcher

[@jbatlanta]

Hi Alan, John (N0HRM) here......I have to quit watching your videos! (subscribed though).....I keep seeing your great equipment and ordering one for myself.......just did it again for that desoldering gun (now the Hakko FR-300) Lusting after your Fluke 8846A, too. GREAT videos. I learn SO MUCH. Thanks!

[@w2aew]

LOL - sorry if my videos cost you money!

[@jbatlanta]

Yes! That Fluke is nice. I also want Alan's brain.

[@donaldfilbert4832]

Love the accessibility of that power supply !! Designed to be very serviceable !!

[@berniken6511]

Nice repair Alan although I did have some trouble with the sound jumping at the beginning it soon cleared though. Hope the ankle is better now.........................Berni

[@dogastus]

Very useful video. I own an FT-736-R myself and it's working fine. After watching your video I wonder if I should swap out all the electrolytics to prevent possible future problems.

[@w2aew]

It's up to you. As the caps start to go bad, you'll notice that the rig will take a few seconds to power up. Gradually, the time grows. If yours is powering up immediately, then you're probably OK for a now.

[@kose2ik]

6:00 R8 & R9 is good desingn (Resistor with heatsink)(left-down(AC input))! But why not degned too R17 & R18 this someway? Heating components need resoldering too (cracks solder heating&cooling).

[@Roy_Tellason]

I would have changed the mounting of those two power resistors as well, make them vertical and away from nearby components, constrained of course by the dimensions of the enclosure.

[@TheRadioShop]

Nice repair Alan. This is the exact same thing I find in all these rigs. Those resistors cook those capacitors pretty good. BTW, still not sure if you got my message two weeks ago.Thumbs up on the repair.

[@w2aew]

I did, thank you!

[@TKomoski]

You can also put fiberglass sleeving on the resistors to keep the heat isolated.

[@paulmorgan1897]

Thank you for the repair information. I hope to get my rig back on the air soon.

[@user-uv4xe3cq2y]

I'd consider new power resistors and extend above the board as high as possible which would move the heat away from the nearby caps and the board itself.

[@godiasdf]

i was thinking the same

[@glenb1356]

I just received a 736 for repair. I did wonder, I would have also suspected the power resistors might be bad. I think replacement of those, and put them a bit higher off the circuit board. 73 Glen K4KV

[@mikesradiorepair]

Classic case of CCS or crappy cap syndrome. One suggestion to those who recap these themselves is to use either 105° C or even 125°C temperature rated caps. To prevent scorching of the PCB upgrade to higher wattage resistors and leave them up off the board slightly for better air circulation.

[@w2aew]

Yep - I used 105° C caps for the replacements.

[@harbselectronicslab3551]

I don't know why they even bother making 85 deg caps anymore......who would bother using them

[@_droid]

Wouldn't moving those power resistors up higher away from the board help keep heat away the other components?

[@w2aew]

Yes, but changing to 105 degree caps should really solve the problem too.

[@mc_cpu]

☣droid☣ yes I was thinking that too, try to add a heat sink for them, didn't like the way that board is getting toasted.

[@richardgoebel226]

Dick, double check the leads of the devices. I found out by accident that some device leads of resistors and capacitors are actually tin coated steel. Old hard drive magnets make them easy to pick up off the floor if you drop them.

[@TheRetiredtech]

Thanks

[@ElmerFuddGun]

Alan, may I ask what video editing software you are using? A number of the transitions were kinda "weird" and I thought my computer might be the problem. Had to check the video on my tablet to confirm it was the video. Hmmm... deliberate so that you get more views? LOL ;-)

[@ElmerFuddGun]

4:35 - 4:53 is a good example showing a number of frames jumping into the video. Pretty weird... Enjoyed the video though!

[@0xffox]

I thought it was my lack of sleep

[@Mythricia1988]

I noticed those flickers as well. And I can with pretty high confidence say he's using Sony Vegas or some derivative of it, because I've had the exact same issue happen in that. Sadly my long (and short) term memory is complete crap, so I can't remember what the problem was, nor how I fixed it. I did fix it somehow though :\

[@w2aew]

Same tool I've used for years. The problem is with how KZbin rendered the video. There is no jumping like that in my original video that I uploaded.

[@JohnKha]

Was very distracting. I know it isn't your fault, so WTH, KZbin?

[@danishnative9555]

I have one of these also, and I have inspected the power supply. Mine has not failed...... yet, and it sure does not have the burned circuit board appearance. I will also say I have used it a lot. That radio has more hours than mine. Nice though that if the board becomes so non-repairable you can just use this great radio with EX power.

[@NormCobbJrTourLife]

I am glad you did this video as I have an FT-736R with this exact same problem. Thank you so much! :D de N1SJK

[@klcbsoft]

Great video (like all the stuff you do)! Is it a typical symptom of caps next to a heat source to fail without showing signs of swelling or (physical) leakage? And while I'm at it: such heat-damaged caps .. I presume they cause excessive currents through standard Switching PS components like their often neighboring diode packs (e.g. MB20100) which will then further the heat-runaway effect? Thanks for your vids! Did someone ever call you the "Mozart of Oscilloscopes"? I hope so, cause you deserve that :)

[@w2aew]

If the caps don't get hot internally (from leakage current, or high ripple currents and high ESR), then they won't bulge. Bulging is due to high *internal* temperatures.

[@keithmagry7707]

Great repair job Alan, and like all your videos, a quality presentation. Thanks for sharing. Best 73.

[@tdnews3963]

When you pulled the supply out of the rig it looked like there was thermal compound on the plate that connected to the chassis. Is there a benefit to cleaning and replacing that thermal paste to help reduce some of the heat generated by the power supply?

[@gatoalfa7]

I'm not sure if it is because of the phenolic PCB, but looks like a "cheap" power supply for the caliber of the rig. Maybe it is older than what I think, early 2010's? Also at the beginning I thought it was a very wimp power supply and the gauge of the output cables was very thin but then learned it is only 25 W, then is probably ok.

[@JohnHill-qo3hb]

I was wondering why you didn't remove the two power resistors and remount them further away from the circuit board that way there would be more air around them and less heat near the replaced caps.

[@w2aew]

The leads weren't long enough to remount them, and I didn't order a replacement pair.

[@curtiscollett1071]

Great video. I'll be doing this repair soon as a preemptive strike. Any chance of a video showing replacement of the electrolytic caps in the main body of a FT-736R?

[@w2aew]

Sorry - the rig is no longer in my possession.

[@kalvinnoble488]

Did you also check out those two resistors that were creating the heat? Are they also still within spec? Perhaps they should be replaced with power resistors of equal resistance value and a much higher wattage value. That might solve the main cause of the problem of creating unwanted heat drying out the electrolytic capacitors.

[@donbeckham]

It amazes me how people keep suggesting replacing the power resistors with a higher wattage value. All resisters with the same resistance value are going to dissipate the same amount of heat, regardless of the power rating. The only reason to use a 1 watt over 1/4 watt resistor is to keep from burning up the resistor. If the existing resistor is dissipating 1 watt, replacing it with a 10 watt resistor will change nothing. It will still be dissipating 1 watt. The only real solution here it to move the resistors further away from the board and/components, or shield or heatsink them, or increase the tolerance of the other components, just as he has done.

[@w2aew]

The resistors were still in spec, so no need to replace them. A higher power resistor will not reduce the amount of heat - it'll just spread it out over a larger area of the body of the resistor. Total heat produced is still the same. Larger resistors would take up more volume, reduce air flow and put the heat source closer to other components (due to crowding).

[@w2aew]

Agreed!

[@michaelswindal428]

I just bought a marine ssb radio on ebay; cannot receive any channels, though the antenna being used is really for cb frequencies. Wondering if there is a way to test reception with a standard signal generator. Thanks for your advice.

[@w2aew]

Yes, of course. You can apply a low level signal from a signal generator to the antenna port - just be very careful not to transmit, you will damage the signal generator if you do.

[@marvinmcgill]

What was that tool u used on the board? Sounded like a srill.

[@firefighter1955]

Hi seen tutorial for changing meter bulbs what voltage are they please..Great instructions on video many thanks

[@w2aew]

They are 12V bulbs. My video showing the replacement can be found here: kzbin.info/www/bejne/Z3bTZIyOfch8sJI

[@firefighter1955]

@@w2aew Thanks very much even I sshod be able to that great inst

[@firefighter1955]

Sent before finishing sorry great video thank you

[@esalmons9063]

Alan, How unsafe would it be to use two Sencore PR570 Variable Isolation Transformer’s to make repairs to a SMPS? Example: the SMPS plugged into one PR570 and the oscilloscope plugged into the second PR570. Is this a dangerous setup?

[@w2aew]

You only need to isolate one of the devices, not both. It is usually not a good idea to isolate the scope.

[@Larryn7luf]

I had hope you had Illinois Capacitor part numbers so I could recap my radio's power supply. I do not know much about Nichicon or Panasonic

[@w2aew]

Panasonic and Nichicon are both well respected, reliable capacitor manufacturers.

[@TRXLab]

Great work Alan! After all it was the 736 :^) Thanks for sharing

[@w2aew]

I'm thankful that it was!

[@Radiowild]

Nice repair! With those added modules, doesn't look like there's much room for venting anyway. Did I see you growing a soup strainer? lol

[@vtradio]

TNX nice instructions. I found this very helpful. 73 Paul AA1SU

[@jeffolynuk6649]

Hi Alan great video! Wouldn't changing those resistors to a higher wattage help with the heat problem?

[@w2aew]

Not very much - they would still dissipate the same amount of power - generate the same amount of total heat, just spread out a little on a larger body.

[@richardgoebel226]

Did you happen to test the other caps afterward just to see which ones were really bad and which ones were so-so?

[@w2aew]

I tested a few. The first two I pulled were very bad. One of the large caps near the power supply had a slightly elevated ESR. All others were still fine, but replaced with 105C caps anyway.

[@richardgoebel226]

Thank you.

[@PapasDino]

Alan - what were the temp ratings of the old caps just out of curiosity, 85 or 105 degrees? Hopefully the replacements will better withstand the heat generated in that area of the supply. 73 - Dino KL0S

[@w2aew]

They were all 85 degree caps. Now, they're all 105...

[@marcioandreyoliveira]

Hi. I'm wondering if you know the answer for my doubt. Suppose one is developing a new electronic circuit and he/she wants to determine which components are more prone to fail. Also, one wants to determine how long it will take for the circuit to fail (1 month, 6 months, 1 year ?) Is there any reliable experimental procedure for that? I know about the MTBF, but it seems a bit unpractical to wait until a circuit breaks. Is there any procedure to "stimulate" the circuit to be in a state as it has aged a specific period of time so one wouldn't need to wait one year or more to see which components fail? For instance, if one makes the circuit run continuously for 72 hours under 70 Celsius degrees then their components will behavior as if the same circuit had been used under normal conditions for a year. I'm not sure whether I could explain myself. Sorry for my bad English. Any help is very much appreciated.

[@w2aew]

There are ways to calculate circuit reliability that are theoretical, but are often used to predict operational life. See this link as a start. www.jedec.org/standards-documents/dictionary/terms/arrhenius-equation-reliability

[@marcioandreyoliveira]

I'll take a look at it. Thank you a lot.

[@ales1609]

Alan, how do you remove the through hole components? Do you have a special drill?

[@w2aew]

I used a Hakko model 808 vacuum desoldering tool.

[@silasmarner7586]

I did this precise repair about a month ago. My filter caps were too tall and I hadda cut a hole in the screen, but subsequently added some light closed cell foam insulation to protect from the case.. There's a website with an entire list from DIgi-Thief for all the parts and the dude adds a small fan with a zener to slow it down to cool things a bit. I added that too. Link here: www.qsl.net/4/4x6on/RADIO%20MANUALS/YAESU/YAESU--FT-736R-PS-Repair.pdf Works great, lasts a long time! Great video!

[@w2aew]

Yes - the Digikey p/n listed in that online references calls out caps that are too tall. You can substitute digikey 493-8014-ND or 493-6121-ND instead.

[@silasmarner7586]

***** thanks. I think they were out at the time......

[@nihonam]

What a beautiful device!

[@w2aew]

It is a nice looking rig!

[@marvinmcgill]

Do u repair these radios? I need my 440 working agoin what happen was I was talking on it forgot to move a ant away from it I had both my 2 meter home made ant next to my 440 at the time got in a hurry talked long enough to call out waited for a few no one came back turned off the radio came back the next day ID up no TX> To me it sounds like a finel on the 440 side

[@w2aew]

I"m sorry, I don't do repairs generally - just for my own rigs and for close personal friends.

[@arrshithrg5359]

what kind of topology is that power supply ,flyback ??

[@w2aew]

I haven't really studied the schematic to be certain, but probably just a crude buck converter I would guess without digging into it.

[@TheRetiredtech]

The4 shortened link to your parts list has expired could you add a fresh one Thanks Garry

[@w2aew]

OK, I've updated the link.

[@TheRetiredtech]

w2aew thanks

[@barn5923]

Alan do you know where I can get a service manual for a Tektronix CMC 251 frequency counter

[@w2aew]

I don't know that I've ever seen one...

[@barn5923]

thanks for your time you are a good man

[@brunofonseca9686]

Nice video as always!

[@PeterWMeek]

It sounds (he wants stock lamps) that the owner wants to keep this rig all original. I think I would have tried to talk him into some non-stock cooling for that power supply. A fan, a heat pipe, something.

[@rayplaag5665]

Perhaps one day ...You could show how you powered this up using a DC power supply ..My 736 is still working fine ..I am sure I will have the same problem one day

[@w2aew]

I don't have this radio any longer, so I can't show you. However, the manual clearly describes how to do this (involves moving a switch inside the unit).

[@rayplaag5665]

TNX

[@marklowe7431]

Its in nice condition. Credit to the owner.

[@far-fieldtechnology8130]

how do you know so much

[@Edmorbus]

Thanks for sharing

[@tlrptg]

don't check the PSU with the rig, right after recapping. test it with some 12 volts light bulbs first. this way you don't risk burning out the transceiver if other faults are still present.

[@w2aew]

Good tip!

[@victornpb]

I would desolder those resistors and put then on wires touching the back heat sink.

[@w2aew]

You've got to be careful when doing things like this in switching power supplies. Depending on where these components are in the circuit - the extra lead length could cause issues with the proper operation (due to extra inductance), or could cause RF emissions which would be detrimental inside of a radio. I figure that it lasted over 20 years with 85 degree capacitors, it will last longer now with 105 degree caps.

[@jamesmasonic]

Woow what was that you used to desolder the caps from behind a kind of drilling machine?

[@w2aew]

It is a Haako Model 808 vacuum desoldering tool.

[@TonyBarr99]

Alan, you really should turn the rig on up-side-down. All of the electrons might fall out. (-;

[@crocellian2972]

Why do hams refuse to make obvious changes like LEDs?

[@w2aew]

In this case - it's not so easy. The meter is back-lit by bulbs inserted into through-holes in a plastic light pipe. Thus, light is coupled out of the sides of the bulb into the light pipe. Most bright LEDs don't emit much light out of their sides, they are focused in the axial direction, thus wouldn't couple well into the light pipe without modification.

[@w2aew]

Not a bad idea. I just don't have an SMD LEDs here to experiment with... I'll check out Paul's amp video...

[@bryanwa7prc647]

Incandescent lamps have a very low cold resistance, resulting in HUGE inrush current. This causes premature failure. I've used an LM317L as a current limiter, resulting in very long lamp life. The caveat is, it drops ≥ 1.25V. So, instead of 14V lamps, I use 12V lamps. I last changed the lamps in my TS120S/TS130S rigs over 10 years ago. With the running current limited to about 95% of normal, lamp life is extended another 50%.

[@bryanwa7prc647]

"Dispersion Angle" isn't a function of the mounting style. It has to do with the LED's lens. If the angle is small, you can remove the lens. The caveat is, the light is then spread over a wider angle, and it appears dimmer.

[@stephanc7192]

Well done!!

[@sreekumarUSA]

Thanks, Alan. 93s

[@NICK-uy3nl]

I would have replaced the two 33 ohm power resistors with higher wattage units to eliminate high temperature dissipation. As it is, it will fail AGAIN, more of a repair than a fix.

[@w2aew]

Higher wattage resistors won't really change anything. The resistors will dissipate the same amount of *power*. Although the resistors will run cooler because the power is spread out over a larger area, the total amount of heat generated will be the same - so it wouldn't change the amount of thermal rise in the power supply enclosure. Adding a fan would help though.

[@NICK-uy3nl]

Obviously, high temperature is the enemy of electrolytic caps, by replacing the resistors with, say 10 Watt units, the temperature CONCENTRATION will drop dramatically in the vicinity of the two failed caps. Stacking two 10W ceramic resistors would probably work in this situation. Remotely mounting the resistors in the PS unit would work even better as far as evening out temp gradient throughout the PS housing. Good video. www.parts-express.com/33-ohm-10w-resistor-wire-wound-5-tolerance--016-33 www.newark.com/welwyn/wh5-33rji/resistor-wirewound-33r-5-axial/dp/98K2889

[@w2aew]

I agree that the temperature gradient will change by changing/enlarging the source of the thermal energy, and that would have to be traded off against the reduced airflow around the larger resistors (since we're still talking about the same amount of thermal energy, just spread out more). Remote mounting is a good idea too (even better), provided the extra parasitics from the longer wiring doesn't affect the supply operation.

[@NICK-uy3nl]

Well, one thing is for sure, the original resistors are way underrated and the way they are mounted they hardly get any air circulation around them to dissipate heat, anything to address that will fix the problem.

[@indigoskywalker]

Nothing like a de-soldering iron/station 😂

[@namjignerak]

Planned obsolescence.

[@senohpi]

it´s obvious why we call the desolderinggun a "cow" :)