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Galaxy RG-99 issue

W

wrongway

Member
Sep 10, 2011
12
0
11
I have a Galaxy RG-99 i am playing with . I believe it has a heat issue . The radio works fine for about 3 to 3 1/2 hours and then the transmitted audio starts to cut in and out . I am guessing an ic is getting hot and acting up . With meters attached i can see that the AM power is not affected while it is acting up , the modulation does get real bouncy when it acts up . It is very stable for 3 hours every time , then it becomes random and eventually permanent . Any ideas on what this could be ? I have been over and over the solder joints .
Thanks in advance .
Don
 

I may have this solved , IC8 which is a TA7222ap audio amp is not secured to the radio chassis . There is some heat sink compound on the ic and chassis so it used to be attached . The remnants of the plastic screw are in the threads so i will need to scrounge up a plastic screw . Once i do this i'll run it tomorrow and see what happens .
Don
 
Well it was not ic8 , the radio started acting up 3 hours and 10 minutes after turning it on . Does anybody know of another ic that would affect just the transmitted audio and not the AM power . The modulation does get jumpy when it acts up but that's probably due to the lack of audio when it cuts out .
 
i'm not familiar with that radio, but look to see if it has a 4558s or 4558d audio preamp. most types of chassis based on the uniden pb010 chassis use this type of preamp.
 
Thank you for the reply , yes it does have the 4558D . This is the 690010z main board . If this ic is the problem i wonder if it is a bad ic that gets goofy after a while or if maybe it is getting too much voltage causing it to run hot and act up . I guess my next step will be to pull the data sheet and make sure the supply voltage is in spec .
 
pro151 said:
I've never heard of a Galaxy RG-99. Ranger, yes. Got a pic of it?
Click to expand...

RANGER%20RG99.jpg
 
Sorry been away from the computer for a few days . I sure feel stupid right now , it is a Ranger . I must have had Galaxy on my brain when posting this . In any case i replaced the 4558D and it started breaking up just over 3 hours into use . Back to the drawing board i guess . Sorry for the Galaxy / Ranger mistake .
Don
 
wrongway said:
Sorry been away from the computer for a few days . I sure feel stupid right now , it is a Ranger . I must have had Galaxy on my brain when posting this . In any case i replaced the 4558D and it started breaking up just over 3 hours into use . Back to the drawing board i guess . Sorry for the Galaxy / Ranger mistake .
Don
Click to expand...

time to start checking if all your oscillators are running correctly and not self oscillating when the fault shows, i'd be checking out the vco is running correctly too.

i'd also be looking to the am modulator/voltage regulation circuits to make sure none of those transistors are thermally intermitant.
 
Thank you for such an in depth reply , that is the kind of info i need . Now if i only knew what to do with it . I found a thread here with some good testing methods for transmit trouble . I will need to purchase a scope for this though as well as set up a base antenna . This gives me yet another reason to buy a scope , my other hobby is pinball and video machines and i can't count the times i have needed one . So this radio will be on the back burner for a little while unless somebody bumps this thread up with some things to try .
Thanks again
Don
 

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