Yaesu Ham Radio, not putting out any power, FT-7100M

[KRS]

Good evening,

My faithful FT-7100M stopped working, took it to a friend's house with an SWR/PWR meter; it's not moving the needles at all.

Removed my diamond mag-mount antenna base, removed the element, and tested mount/cable for continuity and it appears to be fine.

The antenna element (2m/440) has no continuity between the wire vertical element and the gold center pin inside the base of the antenna element... shouldn't there be continuity there?

There is continuity between the top part of the antenna and the bottom piece (separated by a hard black rubber piece). That doesn't seem right at all.

So, if I'm right about the antenna; I think this effected the radio.

I'm not sure what to do next to test it and figure out a repair.

Any help would be appreciated.

KRS

 

[LippCJ7]

Re: Yaesu Ham Radio, not putting out any power, FT-7100M

Your probably right but the best way to check any radio is to put a vswr meter and check for power if no power then put a dummy load in place of antenna and check again, reason being theres some radios that will automatically shut down if they see high reflected power. The problem is not knowing the characteristics of your antenna, you should have continuity throughout the center conductor however I have seen some(rare) that do not. So the way to deal with this in the professional realm is to place a dummy load in place of the antenna to check power, if you are still showing no power then its time to check power and ground, if you have good power out then replace antenna. if not then pull the radio and start tearing it a part. Now heres where things get expensive, most radio shops charge $85 to $100 an hour to fix your radio and usually a 1 hour minimum so you have to figure out if your radio is worth it to fix or not.
If you don't have a dummy load another known good antenna will work in a pinch.
Hope this helps

 

[KRS]

Re: Yaesu Ham Radio, not putting out any power, FT-7100M

Tried a good, known 1/2" pipe copper j-pole and the radio won't open up a very close repeater.

Thought maybe there is an internal safety mechanism to save the transmitter that would shut down if the antenna went bad, so unplugged the radio power for 5 minutes and tried again, no change.

I don't own a dummy load. Did use friend's SWR/PWR meter with his antenna though just to be sure, no output.

KRS

 

[LippCJ7]

Re: Yaesu Ham Radio, not putting out any power, FT-7100M

Sounds like you blew the PA out of it, Pretty common when running high reflected, I would check the antenna against your buddies radio with the VSWR meter, hit it one or two times for a couple seconds only(won't hurt the radio), anything more then 10% reflected is no good. Might be worth checking to see if you can buy one online, I don't have any experience with your unit but if its modular like a motorola you should be able to purchase a PA if not then your looking at a component or three and would need a tech to look at it.

 

[KRS]

Re: Yaesu Ham Radio, not putting out any power, FT-7100M

Checked the radio on that antenna with an in-line SWR/PWR meter; didn't even deflect the needles. Tried a known-good copper j-pole antenna; didn't move the needles at all.

No power output.

 

[LippCJ7]

Re: Yaesu Ham Radio, not putting out any power, FT-7100M

Checked the radio on that antenna with an in-line SWR/PWR meter; didn't even deflect the needles. Tried a known-good copper j-pole antenna; didn't move the needles at all.

No power output.

Well then, unless your pretty good with a schematic or a service monitor I think its time to find a place to fix it or just buy a new one, any idea what its worth? What part of Arizona are you located?

 

[KRS]

Re: Yaesu Ham Radio, not putting out any power, FT-7100M

I'm located in Southeast Arizona, in Sierra Vista (by Fort Huachuca).

Tried transmitting again with an HT close by and I could pickup the RF transmission on the HT, so everything is probably working up to the final.

Tried googling the transistor and couldn't find it: 2SK3478 MOS FET

I'm not an electronics guru by any means, but I can solder.

The radio was in the truck when I bought the truck from my father, so I didn't see the retail price. Saw MSRP and it was suggested at $475. Don't want to junk it but don't want to pay too much to get it fixed. AES quoted $150 + shipping for repair.

KRS

 

[LippCJ7]

Re: Yaesu Ham Radio, not putting out any power, FT-7100M

http://www.creativecom.com/locations.html I Don't have any info on this company, they bought the Motorola service centers long after Motorola laid me off and I moved to Colorado (Tucson is my Hometown) if they can't fix it they should know where you can go. That transistor is probably discontinued but there should be an upgraded replacement for it, is there a manufacturers name or icon on it?

 

[LippCJ7]

Re: Yaesu Ham Radio, not putting out any power, FT-7100M

Have you tried Yaesu/Vertex?

For Technical Support or Customer Service call, (714)827-7600 between 8AM ? 5PM PST

For Parts Department call (714)827-7600 (8AM ? 5PM PST)

Could be a help, since I am having a hard time locating parts online as you are.

 

[KRS]

Re: Yaesu Ham Radio, not putting out any power, FT-7100M

I'll try Yaesu too.

Here's the innards.

The three red arrows point to three tiny little green 'boxes' that appear to be soldered on the tabs of the final transistor. Any idea what these are?

 

[KRS]

Re: Yaesu Ham Radio, not putting out any power, FT-7100M

Bigger picture:

http://i40.photobucket.com/albums/e207/azfyrfyter63/FT7100mlines.jpg

 

[LippCJ7]

Re: Yaesu Ham Radio, not putting out any power, FT-7100M

I'll try Yaesu too.

Here's the innards.

The three red arrows point to three tiny little green 'boxes' that appear to be soldered on the tabs of the final transistor. Any idea what these are?

I'm guessing diodes but without it in front of me hard to tell you could put a DVM and measure it both ways it should read good one way and open the other if they are good. Whats the big black burn looking thing on the lower left part of the transistor?

 

[tx1961whaler]

Re: Yaesu Ham Radio, not putting out any power, FT-7100M

Bigger picture:

http://i40.photobucket.com/albums/e207/azfyrfyter63/FT7100mlines.jpg

Probably tuning (matching) capacitors for the finals

 

[Bob_VT]

Re: Yaesu Ham Radio, not putting out any power, FT-7100M

I have ICOM HT and mobiles and I will be honest....... my neighbor is a Kenwood repair guy and he will not touch my ICOM's and in the past has told me to send them in to the "factory facilities"

I have had to send in my HT to ICOM and my friend sent his Yausu in to get his fixed....... well worth the expense.

It seems as if every time you run into an Elmer they are great with ONE particular radio. There are allot of model changes so I surrender to factory repairs quick.

I have only had nothing but good things to say about factory repairs...... worth the money.........

 

[flycaster]

Re: Yaesu Ham Radio, not putting out any power, FT-7100M

I'm located in Southeast Arizona, in Sierra Vista (by Fort Huachuca).

Tried transmitting again with an HT close by and I could pickup the RF transmission on the HT, so everything is probably working up to the final.

Tried googling the transistor and couldn't find it: 2SK3478 MOS FET

I'm not an electronics guru by any means, but I can solder.

The radio was in the truck when I bought the truck from my father, so I didn't see the retail price. Saw MSRP and it was suggested at $475. Don't want to junk it but don't want to pay too much to get it fixed. AES quoted $150 + shipping for repair.

KRS

The boards contain "surface mounted components" which are not for the amateur to be trying to repair. The components are small, pad locations are small and they do not like a lot of heat. Also circuit spacing is very close and more than likely a solder bridge will occur and not be detected by a "novice"
BEST TO SEND TO A FACTORY REPAIR FACILITY.
WD4ODS

 

[KRS]

Re: Yaesu Ham Radio, not putting out any power, FT-7100M

Whats the big black burn looking thing on the lower left part of the transistor?

It brushed right off, so it wasn't part of the transistor.

 

[Fl_Richard]

Re: Yaesu Ham Radio, not putting out any power, FT-7100M

It probably was part of it once.

As part of the manufacturing process all electronics go thru a smoke injection process. The problem is your outputs have failed allowing them to release their smoke and they will no longer operate.

I'with the factory service crowd. They will fix AND test it to ensure your system doesn't jam local flight operations.

 

[LippCJ7]

Re: Yaesu Ham Radio, not putting out any power, FT-7100M

The boards contain "surface mounted components" which are not for the amateur to be trying to repair. The components are small, pad locations are small and they do not like a lot of heat. Also circuit spacing is very close and more than likely a solder bridge will occur and not be detected by a "novice"
BEST TO SEND TO A FACTORY REPAIR FACILITY.
WD4ODS

Yeah we use Hot air bonding all the time, we have three in our biggest shop because the techs get backed up waiting for one. pretty cool process. HAM radios are not backwoods stuff of course I wouldn't put them on the same level as Motorola or Ericsson so I think the guys are right, probably time to seek professional help, if I had a Yaesu guy I would help you out unfortunately I don't. We do play with Icom's though, not that it helps you, were mostly Motorola, Kenwood and a few others depending on what the customers pickup.