Audio chip for a connex 3300HP ?

[newoldguy]

I have this connex 3300hp that i bought on ebay the transmit and modulation are working very well but there is no recieve. I did check all the usual mic ext speaker squelch even on pa there is no recieve i pulled the audio ic and there was a TA7222 in it I replaced and same thing i was just wondering if that was the correct audio chip I know they use them in the cobra 29's but thought the bigger radios used a different chip ? can anyone confirm ? and thanks

 

[Unit 75]

Yes, That is the correct audio IC.

 

[newoldguy]

Yes, That is the correct audio IC.

Thanks 75 i guess back to the chalkboard lol im going to order a few more hoping i just had a bad one

 

[Unit 75]

I think your audio IC may be fine if you have modulation. You can take some voltage measurements on the pins of the audio IC and post them here for me to look at. I'm thinking you may have an issue in your receive chain coming in. Take a look at TR17 and take some voltage measurements on that transistor and post your findings here.

 

[Dmans]

Microphone wiring?

 

[NZ8N]

The audio IC in a Connex 3300 does not provide modulation to the transmit section.
Have you tried it in PA mode? This would route the microphone audio to the audio IC to test it.
Does the signal meter move when it receives a signal? If it does, the problem is further down the line, maybe TR15 which is the RX audio buffer before the audio IC, or the squelch clamping transistor, TR16.

 

[Unit 75]

The audio IC in a Connex 3300 does not provide modulation to the transmit section.

Sorry, I meant audio/modulation in PA mode.

 

[Unit 75]

I did check all the usual mic ext speaker squelch even on pa

Sounds like he did check PA mode or maybe I'm reading his post incorrectly?

 

[newoldguy]

The audio IC in a Connex 3300 does not provide modulation to the transmit section.
Have you tried it in PA mode? This would route the microphone audio to the audio IC to test it.
Does the signal meter move when it receives a signal? If it does, the problem is further down the line, maybe TR15 which is the RX audio buffer before the audio IC, or the squelch clamping transistor, TR16.

it does not have audio on pa i tried that and the meter doesn't move at all i tried everything i could thik of to try to get some kind of noise from it transmit section is good just no recieve at all and thanks for the reply i will look at tr 15

 

[newoldguy]

I think your audio IC may be fine if you have modulation. You can take some voltage measurements on the pins of the audio IC and post them here for me to look at. I'm thinking you may have an issue in your receive chain coming in. Take a look at TR17 and take some voltage measurements on that transistor and post your findings here.

I will get some readings tomorrow and post up thanks for the reply

 

[Unit 75]

I would look at TR17 first, as mentioned in my above post. It is the first amp in the receive chain from your antenna. Most receive problems with your model radio are attributed to that transistor going from static discharges during thunderstorms when you still have your coax connected to the radio. If it checks out ok, then you can move on down the line until you find the fault, Good luck

 

[newoldguy]

I would look at TR17 first, as mentioned in my above post. It is the first amp in the receive chain from your antenna. Most receive problems with your model radio are attributed to that transistor going from static discharges during thunderstorms when you still have your coax connected to the radio. If it checks out ok, then you can move on down the line until you find the fault, Good luck

great info and thanks im going to check it but to clarify we pretty much ruled out the audio chip?? im going to check tr17 and tr 15 as NZ8N posted
I really appreciate the help and info

 

[Unit 75]

Not yet, 202. Still waiting on the voltage measurements from each pin on that audio chip.

 

[nomadradio]

Does the LED on the front change from red to green when you key the mike?

If not, the PLL may be out of lock. This will shut down the rest of the radio and lock out the transmitter.

Never assume there's just one problem. Quick test for the audio chip is the "Manual Digital Signal Injector". Lay one finger along the shaft of a small screwdriver. Touch the tip of the shaft to pin 4 of the TA7222. It's the fourth pin counting towards the back, starting with pin one at the front-most end.

Should get a loud hum. If not, there is a problem with the speaker audio. Maybe the chip, or the external jack or the speaker.

Or maybe all 3.

73

 

[newoldguy]

Does the LED on the front change from red to green when you key the mike?

If not, the PLL may be out of lock. This will shut down the rest of the radio and lock out the transmitter.

Never assume there's just one problem. Quick test for the audio chip is the "Manual Digital Signal Injector". Lay one finger along the shaft of a small screwdriver. Touch the tip of the shaft to pin 4 of the TA7222. It's the fourth pin counting towards the back, starting with pin one at the front-most end.

Should get a loud hum. If not, there is a problem with the speaker audio. Maybe the chip, or the external jack or the speaker.

Or maybe all 3.

73

it does have transmit and swing it keys rite on freq i just got home and getting the shop warmed up to get
the voltages for 75 i will try what you suggested also