Teaberry Stalker XV No RX audio / no TX need help

[RichardHartman]

Thanks for taking the time to read this.

I picked up a TB Stalker XV base. When first plugged in it turned on, indicator lights and channel selector. I noticed there was no sound (yes the mic was plugged in) so I plugged into the headphone and external sp jack but still no sound (I do here clicking in the speaker when turning off and on) . So next I pushed the PTT and no TX doesn't even switch into TX mode. Meter does not move and its not stuck. Next I looked into the mic wiring the plug was correct but the PTT internal wires were not (someone changed the cord). I removed and replaced the wires correctly ..verified on my Cobra 2000 it works as it should now. Plugged back into the TBerry and still nothing has changed. Moving on to trouble shooting the obvious things ..CB/PA switch dirty so cleaned and working correctly now. Cleaned the NB/ANL and its working correctly but still nothing has changed. It does have a channel mod and the clarifier mod. Noticed the either the MB3756 or the TA7222P(mounted beside each other) was getting extremely hot ..heat sink was hot to touch. This was fixed when I rewired the mic correctly. Checked the voltages on the IC's listed in the service manual - 4 IC's were correct on all pins but IC2 MB8719 - 18pin is not. Upon inspection #18 in not in the thru hole(ground) they have it not hooked up to anything pin is bent up away from the board not used. Now the voltages...per service manual Tberry Left side is manual right side is actual readings
1-3v,----- 1-8v
2-4v,----- 2-4.7v
3-5v,----- 3-4.3v
4-3v,----- 4-166mv
5-3v,----- 5-52mv
6-8v,----- 6-52mv
7-4v,----- 7-8v
8-4.5v,----- 8-4.87v
9-8v,----- 9-1.75v
10-0v,----- 10-1mv(continuity to ground)
11-4.8v,----- 11-3.7v
12-0v,----- 12-5mv(continuity to ground)
13-0v,----- 13-8v
14-4.8v,----- 14-5mv(continuity to ground)
15-0v,----- 15-8v
16-4.8v,----- 16-8v
17-3.5v,----- 17-8v
18-0v,----- 18-0v but not to ground-not being used

So I guess I need to know do you think the PLL is bad or is there something else I need to check that would cause these incorrect voltages?

 

[Dmans]

Pin 18 on that PLL chip is ground. Without it, nothing happens with the PLL.

Are you sure it is pin 18 that is disconnected?

73
David

 

[RichardHartman]

Pin 18 on that PLL chip is ground. Without it, nothing happens with the PLL.

Are you sure it is pin 18 that is disconnected?

73
David

Thank you David you ae correct. I was wrong on the order. These are the correct readings...
1- 1.74v
2- 4.8v
3- 8v
4- 49.7mV
5- 49.7mV
6- 163mV
7- 4.3v
8- 4.7v
9- 8v
10- Not connected but solder pad goes to ground-should I solder this pin?
11- 8v
12- 8v
13- 8v
14- 4mV has continuity to ground
15- 8v
16- 4mV has continuity to ground
17- 3.69v
18- 0.2mV has continuity to board ground but not chasis ground.

 

[loosecannon]

right away when you plug in a radio and only get the meter lights and channel display that says that the MB3756 voltage reg is bad.

you said that the heatsink connected to this device was getting hot which also points to it.

however you are showing 8 volts on pin 9 of the PLL so that would say that the voltage reg is doing its job.

pin 10 of the PLL in this chassis should be grounded, and if it's not, it's because someone wanted to do a channel mod to it, so re-solder it where it went.

you have no voltage on pin 6 of the PLL which is your lock detector pin and it should be sitting at 8 volts. most likely this is because pin 10 is disconnected.

once you have pin 10 reconnected, check the voltage on pin 6, and you should get 8 volts.
if not, first thing to do is try to align the VCO coil per the service manual found here:
http://www.cbtricks.com/radios/teaberry/stalker_xv/index.htm

if you still don't get RX/TX after all this as indicated by the LED, you can try lifting one end of D25.
if this restores operation, then the problem is in the lock detector circuit itself, if not, you have other PLL/VCO problems.
LC

 

[Dmans]

^^^^^
What he said.

73
David

 

[RichardHartman]

right away when you plug in a radio and only get the meter lights and channel display that says that the MB3756 voltage reg is bad.

you said that the heatsink connected to this device was getting hot which also points to it.

however you are showing 8 volts on pin 9 of the PLL so that would say that the voltage reg is doing its job.

pin 10 of the PLL in this chassis should be grounded, and if it's not, it's because someone wanted to do a channel mod to it, so re-solder it where it went.

you have no voltage on pin 6 of the PLL which is your lock detector pin and it should be sitting at 8 volts. most likely this is because pin 10 is disconnected.

once you have pin 10 reconnected, check the voltage on pin 6, and you should get 8 volts.
if not, first thing to do is try to align the VCO coil per the service manual found here:
http://www.cbtricks.com/radios/teaberry/stalker_xv/index.htm

if you still don't get RX/TX after all this as indicated by the LED, you can try lifting one end of D25.
if this restores operation, then the problem is in the lock detector circuit itself, if not, you have other PLL/VCO problems.
LC

OK.. I soldered pin 10 in its proper location - #6 is still at 163mV - VCO I'm assuming is the Alignment for the carrier oscillator? Anyway Freq on target no alignment needed. Thought I would mention that MB3756 all voltages are correct but on IC1 UHIC007 pin 5 should be 3v but its only at 1.74v (pin1 on 8710 supposed to be 3v and its also at 1.74v) coincidence?? So alignment of the PLL process has you adjust voltage to 3.5 but it stays constant at 1.74v. Thought I would give this info before I lift D25.

 

[loosecannon]

what frequency is the VCO on?
this can be read at TP1.

follow this alignment portion first in order to get the VCO adjusted:


you need to get L18 peaked first, then adjust L13, and make sure L14 is peaked as well.
LC

 

[RichardHartman]

what frequency is the VCO on?
this can be read at TP1.

follow this alignment portion first in order to get the VCO adjusted:
View attachment 41723

you need to get L18 peaked first, then adjust L13, and make sure L14 is peaked as well.
LC

Thanks again for taking the time to help out..

TP1 is at 36.6678
TP9 is 1.74v
TP3 is 7.802usb / 7.798lsb

TP1 should be 34.9875
TP9 should be 3.5v
TP3 is right on target.

As you might guess I am a newbie at this and trying to learn. I now know some of my issue with trying to step into the alignment process only works with the proper equipment. I was trying to use an oscilloscope and signal generator that was in a kit. Not paying attention to detail these pieces only work 0-200khz. So for now I can only check voltages and frequencies. Next step will be getting the correct equipment. I will set this aside until I can properly finish it.

Any tips would be appreciated as I continue to learn.

 

[Handy Andy]

Once you power up the radio unfortunately the PLL IC and with it's Pin 18 is not connected to ground, you may have ruined the chip.

You have oscillators working, you get the mixing, but the PLL chip may be toast.

 

[loosecannon]

i agree with Andy.

trying a new PLL chip is cheaper than getting the test equipment, so you might as well give it a shot.
you can get them on ebay, but it might be from China.
LC

 

[Dmans]

Richard Hartman said he was checking the wrong pin. It was pin 10 disconnected not pin 18. (Post #3)

He still has a good chance of bringing back this classic. Personally I would do a full re-cap, an alignment and go from there.

I never power up a classic without changing all electrolytic first. But we are all different.

73
David

 

[RichardHartman]

i agree with Andy.

trying a new PLL chip is cheaper than getting the test equipment, so you might as well give it a shot.
you can get them on ebay, but it might be from China.
LC

Thank you

I would like to proceed further into radio repair especially on the classics. So at some point I need the equipment anyway.

I was looking on Ebay and around the other day for the PLL. When you buy one does it have to be programmed or anything or should it work as is?

 

[RichardHartman]

Richard Hartman said he was checking the wrong pin. It was pin 10 disconnected not pin 18. (Post #3)

He still has a good chance of bringing back this classic. Personally I would do a full re-cap, an alignment and go from there.

I never power up a classic without changing all electrolytic first. But we are all different.

73
David

Hi David,
I will definitely recap, that is next while Im waiting for the other. Since you seem to do recap often do you have a suggestion on manufacture? I order thru Mouser.

 

[Tokin]

Hi David,
I will definitely recap, that is next while Im waiting for the other. Since you seem to do recap often do you have a suggestion on manufacture? I order thru Mouser.

Mouser is a trusted source of parts.

 

[Handy Andy]

It is not clear how - in direction and layout - he did this voltage chart list.

Hint Pin 9 gets 8 V - but Pin 10 is left floating and may have a voltage of about ~3.2 to 6 volts if floating...

So what is that chart "pins" layout?

​

Lord help us if he used it's service manual...

Per their own info...

​

I just worry - thats all...