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Author Topic: Adjusting idling current on Icom 746 non pro ?  (Read 1582 times)
N4NYY
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« on: September 16, 2009, 06:54:45 PM »

Hi. My Icom 746 non pro TX died. I took it upon myself to repair the unit. The 2SC1972 drivers were shot. I also replaced IC-151 and put in the diode mod.

I then go to align the idling current on the radio according to page 5-4 of the service manual. The very top part, says to connect an ammeter to the supply line, turn R11 fully CCW. Then adjust it to set at 600mA. I am measuring 1.7A in RX, and over 2A in TX. The settings are accoring to the manual. What do you think I am doing wrong?
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N0WXV
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« Reply #1 on: September 17, 2009, 06:07:56 AM »

Break in to the +supply line where it feeds the outputs and see what you get..
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KB2CPW
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« Reply #2 on: October 27, 2012, 02:24:03 PM »

yOU ARE INCLUDING THE TOTAL RADIO DRAW WHEN YOU QUOTE THOSE FIGURES. YOU WOULD ADJUST BOTH THE DRIVER AND FINAL POTS DOWN TO ZERO THEN TAKE THE MEASUREMENT, ADD 600MA TO THAT, THEN THE FINALS YOU WOULD DO THE SAME THING.
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N4NYY
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« Reply #3 on: October 27, 2012, 05:17:19 PM »

yOU ARE INCLUDING THE TOTAL RADIO DRAW WHEN YOU QUOTE THOSE FIGURES. YOU WOULD ADJUST BOTH THE DRIVER AND FINAL POTS DOWN TO ZERO THEN TAKE THE MEASUREMENT, ADD 600MA TO THAT, THEN THE FINALS YOU WOULD DO THE SAME THING.

Nice. My post is from 2009. I have long since sold the 746 and purchased 2 FT-950. Read the date!
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AC5UP
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« Reply #4 on: October 27, 2012, 06:08:23 PM »

Yeah, Yeah, Yeah......... But you're still the same doof.   That's why this thread rings true three years later....................  Roll Eyes
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N4NYY
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« Reply #5 on: October 27, 2012, 06:10:23 PM »

Yeah, Yeah, Yeah......... But you're still the same doof.   That's why this thread rings true three years later....................  Roll Eyes

Hey, I fixed it myself for $60 in parts!
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AJ4WC
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« Reply #6 on: October 30, 2012, 10:57:59 AM »

I think it's a stretch to say you fixed it yourself...
 
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KB2CPW
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« Reply #7 on: October 31, 2012, 12:07:05 AM »

Firstly, I pulled this post up in web logged format on Google and I was already logged into Eham prior. Web logged shows the post with no date and came up in my search for something else. Web logged shows the post, a window and a reply button in google where the date is not shown. Secondly I replied, and you appear unappreciative.

Next time I will bypass your posts. In addition, you never thanked anyone, nor did you even reply with the outcome which helps other hams in their quest to find an answer. When you blow your finals again, surely we will all laugh when you post again seeing 2-3 amps and try to figure out your mistake. Pardon me for trying to help you. Don't bother to reply, you probably won't anyway since that seems to be in your nature.
« Last Edit: October 31, 2012, 12:11:00 AM by KB2CPW » Logged
KB2CPW
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« Reply #8 on: October 31, 2012, 12:10:35 AM »


  Note, the only time the date is shown is when a post is quoted.. When a post is an original there is no date. In other web formats, no date is shown at all on any posts. Below is an example.







IC-746 No Sound When Powered On

<< < (5/6) > >>

Tom Rowinski:
Quote from: N4NYY on May 25, 2012, 06:45:55 PM

The first time I did that by accident, I blew out my backlight.


The backlight circuit in the 746 is a POS design. The backlight would have probably crapped out any way.. just a coincidence it crapped out at that moment. There are only 2 types of backlight inverters used in Icom 746's- those that have faied, and those that will fail.

Vinnie Sallustio:
Quote from: KA1MDA on May 27, 2012, 11:16:40 AM

Quote from: N4NYY on May 25, 2012, 06:45:55 PM

The first time I did that by accident, I blew out my backlight.


The backlight circuit in the 746 is a POS design. The backlight would have probably crapped out any way.. just a coincidence it crapped out at that moment. There are only 2 types of backlight inverters used in Icom 746's- those that have faied, and those that will fail.


That is why I have an FT-950 now. I can tell you this, with LCD displays this cheap, I am surprised that aftermarket replacements for those Icom radio displays have not been designed my someone.

Aaron M. Duke:
I'm still looking for ideas if anyone can help. Thank you.

KQ6Q:
Is your MFJ supply an Linear supply (heavy with a transformer) or a switcher ?
FWIW - I have a 746Pro and when I bought it new, the factory PS-125 switcher (Icom brand)
came at no extra charge.  Perhaps there had been issues with other power supplies, and they decided to start providing a compatible unit free with the original purchase.

Mark Brueggemann:
Quote from: W4JST on May 28, 2012, 10:44:06 AM

I'm still looking for ideas if anyone can help. Thank you.

Do you have, or have access to an oscilloscope?


Mark K5LXP
Albuquerque, NM


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N4NYY
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« Reply #9 on: October 31, 2012, 04:38:11 AM »

I sold this radio in Sept 2009. All the headers are time stamped.
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AC5UP
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« Reply #10 on: October 31, 2012, 06:08:09 AM »

Note, the only time the date is shown is when a post is quoted..

If true, why is this the exact header of the message immediately above yours?


Adjusting idling current on Icom 746 non pro ?
« Reply #1 on: September 17, 2009, 08:07:56 AM »


Scroll up this thread and you'll see it as well..................
It was there before you posted, and it's still there afterward.
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N4NYY
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« Reply #11 on: October 31, 2012, 11:19:42 AM »

I think it's a stretch to say you fixed it yourself...
 

I did the repair myself. That was easy. The cal procedure was a bit confusing. I needed help with that.
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N4NYY
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Posts: 4745




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« Reply #12 on: October 31, 2012, 11:20:23 AM »

Firstly, I pulled this post up in web logged format on Google and I was already logged into Eham prior. Web logged shows the post with no date and came up in my search for something else. Web logged shows the post, a window and a reply button in google where the date is not shown. Secondly I replied, and you appear unappreciative.

Next time I will bypass your posts. In addition, you never thanked anyone, nor did you even reply with the outcome which helps other hams in their quest to find an answer. When you blow your finals again, surely we will all laugh when you post again seeing 2-3 amps and try to figure out your mistake. Pardon me for trying to help you. Don't bother to reply, you probably won't anyway since that seems to be in your nature.


I would have appreciated help on this in 2009. And what are you, the "Thank you police?" I have helped plenty of people here without anyone saying thanks, nor do I care if they do. I will still continue to offer help whenever I can.
« Last Edit: October 31, 2012, 11:27:30 AM by N4NYY » Logged
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