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Author Topic: FT-950 not powering up , MANY have this failure  (Read 20452 times)
N4ATS
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Posts: 820




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« on: October 04, 2011, 12:40:12 PM »

As most of you know , the Yaesu FT-950 really never shuts off , it goes into the sleep mode and when the power key is pressed (CPU Pin 87 thru 10K), the processor is brought out of the sleep mode and goes into the standby mode turning on both the 5 VDC and 12VDC regulators. I have been troubleshooting this radio from pin to pin , mapped the processor I/O's and am wondering if anyone out there has successfully reset the radio from sleep to standby having the typical issue of "not powering up". It appears that the "PRO" lines look at various functions in the radio and if only one function is out of window , power up goes dead and "RESET" stays low. Looking for hard core troubleshooters to jump in...

PS , Been there and done that with Yaesu , they don't know....

I have a stack of these radios with the growing issue...
« Last Edit: October 04, 2011, 12:46:41 PM by N4ATS » Logged
N4NYY
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Posts: 4807




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« Reply #1 on: October 05, 2011, 06:38:27 AM »

I shut my rig off and then shut the power supply off.

I have not read about this problem in the reviews. I replaced an Icom 746, which had the notorious IC-151 and Backlight. Not I am not sure about the standby mode you speak of.

In any case, if you repair these, what is the fix?
« Last Edit: March 01, 2012, 06:13:35 AM by N4NYY » Logged
N4ATS
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Posts: 820




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« Reply #2 on: October 05, 2011, 12:07:41 PM »

I repair many www.n4ats.com but the issue is , there is a serious bug in them that I am about to isolate which causes the radio to stay in sleep mode. Sleep mode is when the radio is shut off by the power switch , it really does not go off , the display and all the panel functions go off BUT the radio (processor) is still on awaiting commands. The only real way to shut off the radio is turn off the power supply.

When this glitch appears (I have seen over a dozen now) the radio will never come out of sleep mode. I have talked to Yaesu many times , there is no one who really understands it so I am mapping all the I/O's to come up with a fix.

I posted this in hopes someone already did , but it appears not. I will publish the fix as soon as it figure it out.
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KQ6EA
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Posts: 609


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« Reply #3 on: October 05, 2011, 08:20:46 PM »

Have you tried removing and replacing the back-up battery? I've rescued many a PC by doing that, and since today's radios are so CPU intensive, it *might* be the best way to do a "hard reset" to the CPU.
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WA0ZZG
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Posts: 158




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« Reply #4 on: October 06, 2011, 12:36:12 PM »

I saw a similar issue in the Yaesu FT-900.  It also had a soft power switch and the CPU kept active as long as there was power applied.  I found that the hard reset wasn't hard enough and sometimes the only way to bring one back to life was to remove the backup battery and let the radio set overnight. This one liked to wink on and then back off.
Recommend this for any radio with issues as a starting point. Sometimes radios can be stubborn and require this be done more than once to get everything back to normal.
Dave...
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N4NYY
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« Reply #5 on: October 06, 2011, 09:14:14 PM »

Quote
I repair many www.n4ats.com but the issue is , there is a serious bug in them that I am about to isolate which causes the radio to stay in sleep mode. Sleep mode is when the radio is shut off by the power switch , it really does not go off , the display and all the panel functions go off BUT the radio (processor) is still on awaiting commands. The only real way to shut off the radio is turn off the power supply.

When this glitch appears (I have seen over a dozen now) the radio will never come out of sleep mode. I have talked to Yaesu many times , there is no one who really understands it so I am mapping all the I/O's to come up with a fix.

I posted this in hopes someone already did , but it appears not. I will publish the fix as soon as it figure it out.

Good deal. They can likely fix it with a firmware update. But they better pay you for it.
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KB3HG
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Posts: 404




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« Reply #6 on: October 11, 2011, 10:08:59 AM »

General observation,
Sounds a lot like the processor cards i use at work. We do a program restart on a first pass if that does not clear the problem a ram clear or worst case pull processor card, remove battery backup jumper and short the electrolytic caps on the card,  Reinstall jumper remount card and reload. noise or a flaky ground can cause this type of problem. I myself find Grounds are not up to par and fix them and generally trouble free for quite awhile. ( A fair sized machine 30 x 40 feet  3 phase feeds lots of VFD, regular ac motors and static.) Don't forget to look at your power.

Tom Kb3hg

PS I have older solid state FTs that show flaky signs once in a while, relays and contacts.
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K2CMH
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Posts: 278




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« Reply #7 on: October 12, 2011, 09:14:25 AM »

I had a non-powering up condition and sent the unit back to Yaesu as it was under warranty.  They ended up replacing a voltage regulator and a couple of transistors.  Although this does not sound like the same issue you are having, I  thought I would toss it out there anyhow.

73,
Carlton
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K2CMH
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Posts: 278




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« Reply #8 on: October 12, 2011, 09:52:06 AM »

Here is something you can try that may help you determine whether or not the radio is just stuck in sleep/standby or if there are other issues at play.  As you have stated, as long as the radio has power, the CPU should be running and the radio listening for CAT commands on the serial port.  On my FT-950, if it has power, when HRD starts, it will connect to the radio and power it up (bring it out of sleep) just as if I had pressed the button on the front panel.  Try powering up the radio using HRD or some other CAT program.  If it powers up then at least you know the radio overall is functioning.  If it does not power up, that may indicated problems other than or in addition to just the soft power switch circuitry.

73,
Carlton
 
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M0HCN
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Posts: 473




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« Reply #9 on: October 12, 2011, 04:48:51 PM »

I don't know what core is in those things, but I do remember a doozy of a problem we had with the IIRC HC12 where it turned out that every 4096th time it was woken up by a state change on a GPIO, well it kind of didn't!

There was a processor errata issued, but still.....
That was FUN to debug.

Regards, Dan.
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N4ATS
Member

Posts: 820




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« Reply #10 on: October 13, 2011, 12:52:46 PM »

Here is something you can try that may help you determine whether or not the radio is just stuck in sleep/standby or if there are other issues at play.  As you have stated, as long as the radio has power, the CPU should be running and the radio listening for CAT commands on the serial port.  On my FT-950, if it has power, when HRD starts, it will connect to the radio and power it up (bring it out of sleep) just as if I had pressed the button on the front panel.  Try powering up the radio using HRD or some other CAT program.  If it powers up then at least you know the radio overall is functioning.  If it does not power up, that may indicated problems other than or in addition to just the soft power switch circuitry.

73,
Carlton

Yep , good one , the CAT is waiting , it also appears that it senses currect out of the PA and if it falls within a window , the BIT is cleared , and reset starts BUT I took a GOOD PA and tried it , no luck

Several folks I know sent theirs back and got replacements, this is NOT a good indication its an easy find / fix. I have mapped the entire I/O with a good processor , they are identical!!!!
 
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N4ATS
Member

Posts: 820




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« Reply #11 on: October 22, 2011, 11:13:31 AM »

Tim , at Yaesu , finally told me that when the radio is powered OFF by the power supply switch and NOT the power switch on the radio , a few transistors and 2 diodes blow on the b+ feed. I will post the part designators when I get back to work Monday
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N4NYY
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Posts: 4807




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« Reply #12 on: October 22, 2011, 03:05:04 PM »

I very nice Tech Special just sold on ebay for $535 that had this symptom.
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N4ATS
Member

Posts: 820




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« Reply #13 on: October 24, 2011, 04:02:02 AM »

There are two sets of repairs for the  FT-950. This one ruled as number one is typical , the other one I will post as soon as I try it.

On the "PA-A Unit"

Near RL5401 Replace:

1) D-5404 and D-5405 with 1N4001 Diodes. 1N914 Diodes will work however 1N4001 will handle more current.

2) Q5402

3) Q5401

This will get power back to the standby control as D-5404 feeds the relay coil  B+
 side and Q5402 pulls the Negative side of the relay to ground.

The other part of the fix will be posted soon.
« Last Edit: October 24, 2011, 05:51:04 AM by N4ATS » Logged
N4ATS
Member

Posts: 820




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« Reply #14 on: October 24, 2011, 10:22:18 AM »

Finally "AFTER" the above fixes are complete , replace the main processor board as Yaesu said the processor probably get corrupted , then it should power up. The preocessor board is pretty cheap and the part number is: CS1964002 (USA Version)
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