Connex 3300 HP frequency problem

[Crossbow]

Hey guys, I have a connex on the bench that has a problem that I have never seen before. Lets say your on channel 20 = 27.205 when you change the channel to say 24 the frequency jumps to 27.415 and will not change to the correct frequency until you turn the power off and back on then everything is ok until you change the channel again. If you stay on one channel then all is fine but once you change the channel your way off frequency on all channels no matter what until you power down and back on. PLL on pin 4 is 10.240 and does not change along with the 8 volts on pin one. These stay locked in at all times. Anyone have a clue what could cause this to happen? Thanks in advance for your help.

 

[nomadradio]

Really sounds as if the wrong binary code is being fed to one or more of pins 9 through 17 on the MC145106 PLL chip.

The channel selector is suspect, especially if it hasn't been cleaned in 15 or 20 years.

Calling it a "Connex" is a bit like "Ford". They make more than one kind, and have been for a fairly long while.

The connectors between the band selector, channel selector and the main circuit board can cause this trouble.

And never underestimate how many odd symptoms will trace back to a solder connection with a fatigue crack around the component lead sticking out the solder side of the pc board. And a part that had oxide on the lead wire or pin when the radio was assembled won't properly adhere to the solder. Sometimes called a "dry" joint, because the solder did not "wet" the surface of the component lead.

More than one possible cause. More than one possible radio. A model number and the circuit-board number would pin down which radio this is on the inside.

Any specific advice would start with knowing which Connex radio this one is. It won't have a model year hidden in the VIN like a car, but the circuit board number will pin down which generation of the radio you have.

73

 

[Handy Andy]

I'm thinking front panel issues, but I second Nomads approach.

These radios do "change owners" when it come to Manufacturing.

:+> Andy <+:

 

[sonoma]

I would check for bad solder joints before I started trying to find bad parts.
you have 2 of the best people trying to help you on this issue.

 

[Crossbow]

Really sounds as if the wrong binary code is being fed to one or more of pins 9 through 17 on the MC145106 PLL chip.

The channel selector is suspect, especially if it hasn't been cleaned in 15 or 20 years.

Calling it a "Connex" is a bit like "Ford". They make more than one kind, and have been for a fairly long while.

The connectors between the band selector, channel selector and the main circuit board can cause this trouble.

And never underestimate how many odd symptoms will trace back to a solder connection with a fatigue crack around the component lead sticking out the solder side of the pc board. And a part that had oxide on the lead wire or pin when the radio was assembled won't properly adhere to the solder. Sometimes called a "dry" joint, because the solder did not "wet" the surface of the component lead.

More than one possible cause. More than one possible radio. A model number and the circuit-board number would pin down which radio this is on the inside.

Any specific advice would start with knowing which Connex radio this one is. It won't have a model year hidden in the VIN like a car, but the circuit board number will pin down which generation of the radio you have.

73

As stated in the topic title it is a connex 3300 HP but did not add the board # EPT360014B
Done ruled out the channel selector as I changed it out with a known good working one.

 

[Crossbow]

I would check for bad solder joints before I started trying to find bad parts.
you have 2 of the best people trying to help you on this issue.

Hey Sonoma, Long time no hear buddy. Hope all has been going well over your way?
Done been through the circuit for cold solder joints. There is nothing you can do to make this radio come back to the correct frequency you know like pushing around on the board or moving parts around. Nothing changes until you power it down then back on and she is locked back on until you change the channel. Craziest thing I have ever seen come across my bench.

 

[sonoma]

Hi Crossbow, at least you have 2 of the best techs looking at the problem with you. problem is so many things cause this sort of problem so maybe they can help you find it.

 

[Handy Andy]

Then look here...
http://www.cbtricks.com/radios/galaxy/dx33hml/graphics/dx33hml_inter_wiring.gif

It is my fear, that you may have ground issue - does the RX/TX work normally?

Because when it "boots" it checks programming pins but if the detent feature of the channel selector isn't working right - the channel selector is "forgotten" and the PLL simply looks at whatever is present on the programmnig pins.



So that means you have a "lock n load" issue with either the return from the channel selector - to "HOLD" the pins while the PLL "SEEKS" the frequency or one of the ADDERS is (or both) have failed.

IC 6 or IC 7 4008 CMOS adders - especially IC7 I have seen fail due to static pokes.

:+> Andy <+:

 

[Crossbow]

Then look here...
http://www.cbtricks.com/radios/galaxy/dx33hml/graphics/dx33hml_inter_wiring.gif

It is my fear, that you may have ground issue - does the RX/TX work normally?

Because when it "boots" it checks programming pins but if the detent feature of the channel selector isn't working right - the channel selector is "forgotten" and the PLL simply looks at whatever is present on the programmnig pins.

View attachment 23996

So that means you have a "lock n load" issue with either the return from the channel selector - to "HOLD" the pins while the PLL "SEEKS" the frequency or one of the ADDERS is (or both) have failed.

IC 6 or IC 7 4008 CMOS adders - especially IC7 I have seen fail due to static pokes.

:+> Andy <+:

Yes Sir Mr. Andy the radio works fine until you change channels. Once you change the channel it will jump up into the E band frequency and stay there until you turn the power off and back on. Once powered off and back on it will be locked onto the channel you are on but once you change the channel it jumps back up off frequency. I will check out the info you posted and go from there. Thanks for all your help.

 

[Handy Andy]

E band eh? (oh sorry Klondike,,,)

Ok, will look into it further on this end.

Now I'm wondering if the radio got dropped and now there damage to the band selector.

Strange but possible,



Bandswitch Pin E and B are "center" so if "B" loses it - E pops up...Hmmm...

HI - Band - Lo switch show ok?

Reasoning - Ground - if B and E are left to themselves, center pin of switch - if you lose ground or lose B+ theres' the jump. BUT it's in the JUMP itself, so it looks to be a GROUND to PIN 18 or 16, of BANDSWITCH, check it (Bandswitch and HI-BAND-LO Switch) to see if they may be the culprit.

Preliminary:
Looks to be Pin 11 and Pin 13 are HIGH when BAND goes HI
Pin 16 and 18 - are OPEN - in HI band
(UPDATE EDIT - Busy day here sorry)

:+> Andy <+:

 

[Crossbow]

We can rule out IC7. Changed it out and still has the same problem. Moving on to the next step.

 

[Handy Andy]

Ok, update Pin 18 and 16 - show OPEN on MAINBOARD "B" no voltage or floating MAINBOARD 13 shorts to GROUND from HI-BAND-LO switch BANSWITCH PIN 13 SHORTS TO MAINBOARD B+ WHEN HI-BAND-LO SWITCH IS IN LO POSITION - SO THAT MEANS "E" SHOWS B+ ON MAINBOARD.

Power off?
"E" and "B+" OPEN when HI-BAND-LO is in LO position,
"B" and "B+" SHORT when HI-BAND-LO is in LO position.
MAINBOARD 13 and G (both right next to each other) SHOW GROUND WHEN HI-BAND-LO switch is in HI (DEAD SHORT)
MAINBOARD 13 WILL SHOW B+ IN LO (SHORT TOGETHER)
OR
PIN 13 and G SHORT TOGETHER WHEN HI-BAND-LO SWITCH IS HI Position
PIN 13 SHORTS TO B+ WHEN HI-BAND-LO SWITCH IS IN LO Position.

Main Board header shown in graphic is 13 NEXT TO G(round) While B+ SHORTS to BANDSWITCH 13 AND MAINBOARD "E" and outputs B+ to PIN11 or MAINBOARD E (Blue wire) While Pin 18 (ORANGE AMBER) SHORTS TO PIN 16 AT BANDSWITCH - MEANING B+ and MAINBOARD "B" (BROWN WIRE) show OPEN and "E" SHORTS TO B+ when HI-BAND-LO switch is in HI

This can get confusing to keep it all straight but what you are doing is what the "mods" for extra channels as separate switches - what they act like - so they did all the figuring out for you.

 

[Crossbow]

Andy, I have checked the band switch and everything looks good wire wise. The hi - low switch worked but done this. Lets stick with channel 20 on D/A band normal on hi. Turn radio on and key up 27.205 like it should be. Flip to low band and we have 25.855 like it should be. Flip back to hi and we now have 27.215 so it jumped to channel 21 with out touching the channel selector. Change the channel to 21 and we now have 27.415 which is E band channel 1. This is where she gets stuck on that band no matter if you got to 22, 23, 24 or back to 20 it will stay on 27.415. Turn power off and back on and we are now back to normal 20 which is 27.205. Change channel selector to 21 and we get 27.215 now go to channel 22 and we get 27.235 go to channel 23 and she locks back into 27.415 and stays there. With out powering off and change channels back to 23,22,21,20 and all channels are locked to the 27.415. It will not go back to normal on any of those bands until you power off and back on then it will be back on the normal channel you have selected on the display. I hope this is making sense on what I am saying.

 

[Handy Andy]

Better than what I was trying to sort out with a Galaxy 33 other here and a DVM - LOL!

WHEW - I can put that back on the shelf and work on your problem - it's interesting that you "jump" one channel when the problem starts - BTW Channel 23 is suppose to be 27.255 - so why this "jump". Hmmm...

Does the channel display stay on the channel but the frequency changes?

Is that correct?

:+> Andy <+:

 

[Handy Andy]

Are familiar with Resistor Arrays? Because this may be the problem of a floating pin somewhere...

:+> Andy <+: