Connex 3300hp almost dead

[OldTech03]

You must be able to think in more than one dimension there are open circuits and there are shorted circuits. If there is a voltage one place it doesn't follow that there will be voltage at the next place just because the schematic says so. There is a lot of real estate between TR41 and TR36 and a good bit of infrastructure in the sense of circuit trace.

 

[Mk121]

Ok everyone it's fixed. Oldtech you were right on the money! D77 was the culprit. It's replaced and it's working beautifully. A big thank you for helping me figure this out, I owe ya. Thanks to everyone else that helped as well.

 

[loosecannon]

You must be able to think in more than one dimension there are open circuits and there are shorted circuits. If there is a voltage one place it doesn't follow that there will be voltage at the next place just because the schematic says so. There is a lot of real estate between TR41 and TR36 and a good bit of infrastructure in the sense of circuit trace.

im not sure i understand what you mean OT03.

if i measure 8 volts on the collector of TR41 with it connected to the PC board, then i am going to read 8 volts along that whole trace, no matter where i measure it.
what am i missing here?
LC

 

[Handy Andy]

I came late to this party - been having a busy time with house and home stuff...

But...


IT would be easier to have said, check for 8 volts, then look at Pin 8, 7 and 7 of IC4 to see why it wouldn't toggle...

But the big clue would be; to have checked for 8V and that would have brought up the display.

 

[Eldorado828]

I came late to this party - been having a busy time with house and home stuff...

But...
View attachment 28985
Better late than never An
IT would be easier to have said, check for 8 volts, then look at Pin 8, 7 and 7 of IC4 to see why it wouldn't toggle...

But the big clue would be; to have checked for 8V and that would have brought up the display.

I came late to this party - been having a busy time with house and home stuff...

Better late than never Andy. Glad to see you back, haven't seen you chiming in for a little while now. Hope everything is A-ok

 

[Handy Andy]

Thanks! Been busy here...

Better late than never Andy. Glad to see you back, haven't seen you chiming in for a little while now. Hope everything is A-ok

Now why did I put seven and seven in there?

Well, maybe it was to wish you all a happy Easter!​

But the issue around the D77 would have kept the Audio line high, forced muting of the chip - but also to pass along that many of these 4558 chips have ESD protection on their pins.

I've seen several "confessed volted-up" boards that have had IC4 as well as other chips in various conditions of "Altered States" where the chip tries to toggle the 7 pin when you key up and pull low pin 5 when you key the mic. This can throw you for a loop if you're not researching it right.

This reminds me of why GEICO is what it is...
​

You also need to look at Pin 8 - it is the "source" pin for all the chips power - it uses the 100 ohm and the Diode - but if the chip falls it will try to sink or power thru current thru the output Pin 7 and if the ESD did it's job, and because of the volted-up condition that caused this - Pin 8 can drop like a rock or run at 1/2 supply rail simply because the output of Pin 7 is sinking into the Zener on TR36 / TR37 toggle combo...as in...ALL the supply rail. Meaning that the TX/RX/Power-Good check bank of pins on the chip is shot.

So just a hint in case all else seems to fail - check for "Volted up" caps being blown - then you may need to replace several chips on the board - and make a call to the customer for the approval of the extra $$$ you have to now do to it...

 

[farmingboy]

Thanks! Been busy here...


Now why did I put seven and seven in there?

View attachment 28988

Well, maybe it was to wish you all a happy Easter!​

But the issue around the D77 would have kept the Audio line high, forced muting of the chip - but also to pass along that many of these 4558 chips have ESD protection on their pins.

I've seen several "confessed volted-up" boards that have had IC4 as well as other chips in various conditions of "Altered States" where the chip tries to toggle the 7 pin when you key up and pull low pin 5 when you key the mic. This can throw you for a loop if you're not researching it right.

This reminds me of why GEICO is what it is...
View attachment 28989​

You also need to look at Pin 8 - it is the "source" pin for all the chips power - it uses the 100 ohm and the Diode - but if the chip falls it will try to sink or power thru current thru the output Pin 7 and if the ESD did it's job, and because of the volted-up condition that caused this - Pin 8 can drop like a rock or run at 1/2 supply rail simply because the output of Pin 7 is sinking into the Zener on TR36 / TR37 toggle combo...as in...ALL the supply rail. Meaning that the TX/RX/Power-Good check bank of pins on the chip is shot.

So just a hint in case all else seems to fail - check for "Volted up" caps being blown - then you may need to replace several chips on the board - and make a call to the customer for the approval of the extra $$$ you have to now do to it...

I came late to this party - been having a busy time with house and home stuff...

But...
View attachment 28985

IT would be easier to have said, check for 8 volts, then look at Pin 8, 7 and 7 of IC4 to see why it wouldn't toggle...

But the big clue would be; to have checked for 8V and that would have brought up the display.

Hello all,
I know this is an old thread but it sorta applies. Can anyone PLEASE tell me where I can get a complete schematic of a connex 3300hp circuit? I’ve searched high and low online and they don’t seem to exist except in small portions on here. I’m trying to repair several different units for our truck drivers and it’s really slow turning the radio over and over trying to follow circuits. Thanks!

 

[Eldorado828]

Hello all,
I know this is an old thread but it sorta applies. Can anyone PLEASE tell me where I can get a complete schematic of a connex 3300hp circuit? I’ve searched high and low online and they don’t seem to exist except in small portions on here. I’m trying to repair several different units for our truck drivers and it’s really slow turning the radio over and over trying to follow circuits. Thanks!

The Galaxy dx-33hml or the Galaxy dx-33hp will get you into the right territory. If it's a newer radio with dual mosfets, the 33hp or 33hp2 (not sure if the hp2 is on cb tricks) will be closest. Same main pcb with slight variances. I don’t think you'll find the exact schem for the 3300.

 

[farmingboy]

The Galaxy dx-33hml or the Galaxy dx-33hp will get you into the right territory. If it's a newer radio with dual mosfets, the 33hp or 33hp2 (not sure if the hp2 is on cb tricks) will be closest. Same main pcb with slight variances. I don’t think you'll find the exact schem for the 3300.

Thanks so much! I'll take a look.

 

[nbsr]

This might help.

 

[farmingboy]

Thanks again!