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FT991 MOD - Where is the CNTL-UNIT ?...

were you able to mod your FT-991 ?

  • I soldered JP3003 but it didn't work

    Votes: 0 0.0%

  • Total voters
    3

Olivier

New Member
Aug 16, 2014
4
0
1
Boston, MA
Hello All

According to the attached MARS Mod, a solder bridge is required for JP3003 on the CNTL-UNIT which can be accessed opening the "bottom cover".

Attached is also a photo of the FT-991 with the bottom cover off, and the CNTL-UNIT is not apparent... the large IC that is showing on the photo of the MARS document is nowhere to be seen...

Has anyone been able to pin-point the circuit where the JP3003 is located ?

Thanks!
 

Attachments

  • FT-991_MARS_Mod.pdf
    577.2 KB · Views: 1,346
  • ft991 open bottom.jpg
    ft991 open bottom.jpg
    1.2 MB · Views: 3,343
  • ft991 open top.jpg
    ft991 open top.jpg
    844.2 KB · Views: 2,256

N3JTN

Member
Jun 6, 2010
32
1
18
74
Hello All

According to the attached MARS Mod, a solder bridge is required for JP3003 on the CNTL-UNIT which can be accessed opening the "bottom cover".

Attached is also a photo of the FT-991 with the bottom cover off, and the CNTL-UNIT is not apparent... the large IC that is showing on the photo of the MARS document is nowhere to be seen...

Has anyone been able to pin-point the circuit where the JP3003 is located ?

Thanks!
I'ts on the Head of Radio
 

Olivier

New Member
Aug 16, 2014
4
0
1
Boston, MA
Thanks a lot for your response. I went ahead and took the head out. The photos are attached.
However I can't pinpoint the area shown on the MARS document ... can you give me a hint ?
Thank you!
 

Attachments

  • ft991head1.jpg
    ft991head1.jpg
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  • ft991head2.jpg
    ft991head2.jpg
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  • ft991head3.jpg
    ft991head3.jpg
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Last edited:

RatsoW8

Supporting Member, W9WDX ARC Member - WD8T
Nov 3, 2009
3,102
1,402
273
West Central Michigan
I think your the first to post here about owning this radio so I'm not sure anyone here has had one apart yet. From looking at the mod on MODS.DK you should be removing the bottom cover of the transceiver to locate the control unit. The schematics you received with the radio should shopw the location of the unit and JP3003. Let us know when you find it.

You could always call Yaesu USA and ask.
 

Olivier

New Member
Aug 16, 2014
4
0
1
Boston, MA
Hello Ratso and thank you for your response. The document on MODS.DK is the same as I have uploaded in my original post. It indicates to open the bottom cover of the radio, and I posted a photo of that too on the first message. The portion of circuit shown on the MODS.DK/MARS photo is nowhere to be found.

Based on N3JTN's post I removed the circuit behind the head of the radio, and posted a photo of it too... but the JP3003 also don't appear there either...

Lastly, based on your recommendation I placed a call to Yaesu USA today to request the "location where to find the Control Unit circuit"... The lady who answered me indicated that they don't have any engineers in the US office and that this is just a sales office... and that engineers would not respond to questions related to circuit inside the unit..

If anyone else has a clue, please let me know !! Thanks a LOT!
 

RatsoW8

Supporting Member, W9WDX ARC Member - WD8T
Nov 3, 2009
3,102
1,402
273
West Central Michigan
The lady at Yaesu was misinformed. That office is responsible for sales but she could have transferred you over to the bench technicians who do the warranty work. I had numerous discussions with those guys when I sent my FT-450AT back for warranty work a few years ago. I suppose there is a possibility they did away with their own technicians but they never removed the tech support info from their USA website.

Even if they did that there still has to be an authorized Yaesu service center in the USA. Otherwise we would have to ship our radios back to Japan for service. Yaesu still lists their US repair and parts centers on their website. Below is the address I shipped my 450 to for service and their phone numbers.

Yaesu USA
6125 Phyllis Drive
Cypress, CA 90630 USA

1-714-827-7600

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

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

222DBFL

Sr. Member
Jul 28, 2013
3,300
1,353
173
Also by looking at the photos you posted, at least the top anyway that I can see there is another plate that needs to be removed. The top cover is just that. Once you have the 1st cover off, have a look at the other screws. There are 6 on top from what I can see. Remove those and see what's underneath. These HF radios will encase the components, vs them being open like a cb radio. This helps with shielding and keeping debris and moisture out. Have another look at the bottom after you get the 1st set of covers off. There has to be another cover there. I know my kenwood ts140s is kinda like this. I can pull the top and bottom covers off and still have to take another cover off to get to the actual components. If all else fails like Ratso said give Yaseu another call and get a tech on the line!! Good luck and be careful in there.
 

Moleculo

Ham Radio Nerd
Apr 14, 2002
9,052
1,365
283
Also by looking at the photos you posted, at least the top anyway that I can see there is another plate that needs to be removed.

I agree. I can see in the mod photo what looks like a molex power connection. In the photo with the bottom cover removed, it looks like the same connector is behind that shield. I bet the solder jumper that needs to be removed is behind that shield.
 

Olivier

New Member
Aug 16, 2014
4
0
1
Boston, MA
The good news is .... thanks to Bob85, I found the CTRL-UNIT !!! I posted below the before/after photos of the mod.

The bad news is after performing the MARS Mod, there is no change whatsoever to the FT-991 TX range. It still doesn't transmit and shows a blinking red-LED when trying to transmit outside of the US Amateur Radio Bands. No matter how many times I press the Fast+Lock when starting, as indicated in the MARS document...

Any comment or suggestions welcome !
 

Attachments

  • ft-991-mars-mod-before.jpg
    ft-991-mars-mod-before.jpg
    562.5 KB · Views: 2,303
  • ft-991-mars-mod-after.jpg
    ft-991-mars-mod-after.jpg
    392.6 KB · Views: 4,971

RatsoW8

Supporting Member, W9WDX ARC Member - WD8T
Nov 3, 2009
3,102
1,402
273
West Central Michigan
You might want to clean up the solder blob on JP3003 and make sure it's making a good bridge between the two sides. ALso make sure you hold Fast+lock, press the power on button and don't release them until the radio is turned on completely.

Aside from just a little redo on the solder job it looks like you followed the instructions Yaesu has out there to do the mod.
 

knowidea

New Member
Mar 5, 2015
1
0
1
58
The good news is .... thanks to Bob85, I found the CTRL-UNIT !!! I posted below the before/after photos of the mod.

The bad news is after performing the MARS Mod, there is no change whatsoever to the FT-991 TX range. It still doesn't transmit and shows a blinking red-LED when trying to transmit outside of the US Amateur Radio Bands. No matter how many times I press the Fast+Lock when starting, as indicated in the MARS document...

Any comment or suggestions welcome !
Has to either be your solder joint or incorrect reset as this mod is tested. Did you have any luck?
 

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