148 gtl made in china

[melaza]

Looks like it still has same issue I get usb/lsb modulation but no am power and modulation strange radio lol.

The part is a smt capacitor.

 

[kaos513]

The part is a smt capacitor.

thanks

 

[kaos513]

Ahhh hard Chinese radio to fix will try more steps if not up for sale as parts

 

[melaza]

Get the value and replace with a THM ceramic capacitor.

Ahhh hard Chinese radio to fix will try more steps if not up for sale as parts

 

[kaos513]

Get the value and replace with a THM ceramic capacitor.

I did replace that part ,but the issue is still there.

 

[kaos513]

what puzzles me is i have all the right voltages and replaced regulator and audio amp also recapped the audio section still nothing changed .

 

[kaos513]

Im starting to wonder if the tda2003 schematic is accurate for this type of chinese radio.

 

[sonoma]

the part you changed for the am regulator the part number is not tr37 or tr41. per the schematic for that radio. not sure what you have changed so far. the am reg is normally mounted on the back of the case and it is a 1409 from what I remember. a tip42 will work in place of it. since you do not have a carrier that is the part I would be trying to find.you will have two parts like this on some 148 radios. one is a 8 volt reg and the other is a am regulator.

 

[unit_399]

Put the rig in AM mode. keyup and measure the voltage at the collector of TR41. Should be around 7-8 vdc. No voltage = bad regulator. If reg output is ok, then check the collectors of the driver TR38 and the final TR36 for the same voltage when keyed up in AM. If the voltage is ok at the regulator but not at the driver/final, then the mode switch is open in the AM position. If the voltage is present at all three transistors, then the AM regulator is ok and maybe the unit is going out of lock. Look at the output of the tx mixer IC5 in all modes with a counter.

- 399

 

[kaos513]

Will do report later on my findings i have a texas instrument tip42 will replace that part and report back.

 

[kaos513]

I did replace the am regulator its located back of radio attached to chasis

 

[sonoma]

what is the voltage on all 3 legs?

 

[sonoma]

I just reread your postings and you said you checked all the caps. what did you do to check all of them? also check the voltages at ic4 a 3 legged trans. and see what voltages you have from the mode switch as 399 mentioned.

 

[kaos513]

yeah i pulled one cap at a time and tested them

 

[sonoma]

what I should have asked was how did you test them and what did you use to verify they are good. what was the esr range om them . some people just try to use a ohm meter on them to test. did you you use a proper cap tester.