148 GTL PC-412

[kopcicle]

Or, next victim.
I have three all of a sudden and no two are alike.
I'll just call this one #1.
A real cream puff. Seems to have been taken out of the box and...
RX
TX
On freq
TX SSB audio
TX AM audio
PA audio
No RX audio.
I did find and replace bad C176 that was pulling pin 10 down to 6.5V
Working off the 2000 manual as my copy of TR296 has too many variations
In search of RX audio ...

 

[nomadradio]

C186, 220uf at (frequently) 10 Volts.

It shorts and shuts down TR43, the volume-control amplifier. Has no effect on transmit.

73

 

[kopcicle]

C176 annnnnnnnnd ...
C186
Next
Thank You Again , Still?

 

[Handy Andy]

PA would also pipe RX.

So if you don't get that - how about Mic? Short pin 3 to 4 - does speaker pop?

IF so - the RX Speaker return ok...

While you have Pins 3 and 4 connected - check Squelch control - does hiss pop in and out at you rotate thru the control range? No audio? C72 is Audio Amp detector cap.

Still no audio?

Also check routing of PA and EXT speaker - That is thru CB/PA switch one pole handles the Speaker routing so if CB side is "dead" may be due to switch contact. C174 and C175 tie that wire thru to the AM Regulator.

 

[kopcicle]

C174 and C175 tie that wire thru to the AM Regulator.

Absolutely an part of my regular diagnosis

Sooo
#2
Meter lamp
C143
D12
D13
D14
D16
C30
C33
C175 ;-)
L4
TR14
L5
A"few" other parts including C186 and C176 ;-)
It cooked D402 as well as L401 and L402 (DC input chokes)
Vaporized a portion of the DC input trace(s)


Annnnnnnnd ...

It works. It works well enough that it got the minimal controlled carrier mod w/o removing the AMC or ALC and got the TX locked to RX.

Next