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Lasthighlander
Junior Member
Username: Lasthighlander
Post Number: 11
Registered: 8-2004
| | Posted on Friday, September 03, 2004 - 11:07 pm: | 
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I have a used Galaxy 44, I started going through it because the receive is very poor and thought maybe it needed an alignment. I started looking through the radio and found the mirror board was gone and jumpers installed, the bias pots gone and resistors installed. The audio IC is very very hot, I changed it from a 754 to a 817 hoping it would at least help but it didn`t. I replaced the modulation limiter and rebiased it, it has the swinger mod in it, I set low power at 2 watts,and high at 8 Watts. I noticed the modulation flaked out if the low power was under 2 watts.It swings about 14 watts and has a average of about 5 watts with my current settings. Any ideas on what could be over heating the audio IC? I am thinking it is the missing mirror board and most likely a too high a bias? Just my thoughts but any help would be greatly appreciated.
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Lasthighlander
The mirror board is gone because of a modification that eliminates it.
As far as audio chips go, they always run relativly hot. That's why they are mounted to the chassis to get as much heatsink as possible.
On another note, the 2SB-754 is a 60 watt, 7 amp power regulator. The 2SB-817 that you replaced it with is also a power regulator, neither of which are audio chips. The audio chip is located on the same frame rail but is closer to the middle. It is more than likely a 10 pin Toshiba with a TA7222AP number on it.
Here's something you can try to bring the receive up. If you have a little analog (non-digital) AC volt meter, hook the leads to the speaker and have the radio turned up a bit so the meters' needle is moving or at least hearing some noise. Now adjust L-3, L-4, L-6, L-7, L-8, L-10, L-11 and L-12 for maximum indication on the AC meter.
If there is no improvement in receive, then I would be replacing some diodes in the receive section. I have a funny feeling that your radio got hit by some 'close-by' heavy RF.
Jeff
Tech548 |
Lasthighlander
Junior Member
Username: Lasthighlander
Post Number: 12
Registered: 8-2004
| | Posted on Saturday, September 04, 2004 - 9:01 am: |
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Thanks Jeff,, will give that a try,Hopefully it will bring up the recieve on it. The radio sounds great on transmit, I get alot of compliments on it. |
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