Cobra 148 GTL China

[Larry Pridgen]

Thanks Guys,
I have emailed Cobra and I even contacted Dynascan. No reply from Cobra and Dynascan.
I am a retired American living in Australia for 30 years. I am a Ham radio operator (VK7LAZ) and just like to play around with electronics. This 148 gtl is just something for me to do, I will give it away when I get it working.
The mounting of the TDA2003 is not a problem, I just thought someone would have tried this mod before and I could connect the 5 pins to the 10 pin board in the right order. No worries, the TDA2003s are cheap and I have 10 of them so it doesn't really matter if I don't get it right on the first go.

73's
Laz

 

[TM86]

This updates post #5 - for clarity....no it's not a stepper motor driver..

Darn, I was looking forward to the volume knob moving on its own.

 

[Handy Andy]

IT's why I asked Nomad about the PC board maker options - we don't get a lot of converted radios - but we are looking at options of simplifying what 7252AP does in regards to the 7222AP.

The YD-1022 is still a 5 watt chip even though they say it's 10 watts - better look at the scope before you get your hopes up too much.

I took the pics I did while the boss' on lunch, otherwise he get's pissed.

We (the boss and the crew) are just seeing the part supplies dwindle and get more costly - we've thought about 3-D printers and such with point to point SMD - and in fact we have some projects that are tooled and RTG (Ready To Go) as far as replacing Legacy stuff. - but he (Boss') is 70+ and wants to retire - he just sees this as a side line and pays the crew as such. We're not millionaires doing this - and he wants to just break even and he's done. We just get a free lunch. It's not even full time - we just "schedule" and pencil ourselves in - just be honest and you get called back...

I just have a great bunch of folks I can work alongside and not fight - we get along just fine. All the logistics and inventory is still done by him - so much so that he knows more about the parts than the radios' but when it comes to part numbers - he has all the cards - he knows whom to call. And they deliver it in less than a week. You don't see too many walking Rolodex with a memory recall like his. He barters - so what we have excess of, he deals and ships - trades - for what we need.

 

[kaos513]

Dont know if applies to cobra 148 gtl below is a link:

http://downloads.cobra.com/CB/Models/29-SERIES/YD1022_Audio_Amp/YD1022changeList.pdf

 

[nomadradio]

Okay, so here's an idea.

The TDA2003 gets a tiny pc board attached to the pins, with the all-important power-supply bypass caps on it.

It gets mounted to the original mount hole, but upside-down. This prevents clearance issues with the circuit board.

Wires would be needed to reach down to the pcb pads where the old parts' leads were lap-soldered.

No, I haven't done any more than just pull this out of my, uhh......

Just an idea so far.

73

 

[Handy Andy]

Look at the ribbon to the Front panel of the PC-122 - it was at this moment I woke up - but that idea stuck in my head to use that ribbon cable to run down to the edge connector.

 

[Larry Pridgen]

Okay, so here's an idea.

The TDA2003 gets a tiny pc board attached to the pins, with the all-important power-supply bypass caps on it.

It gets mounted to the original mount hole, but upside-down. This prevents clearance issues with the circuit board.

Wires would be needed to reach down to the pcb pads where the old parts' leads were lap-soldered.

No, I haven't done any more than just pull this out of my, uhh......

Just an idea so far.

73

Thanks Nomad,
I have mounted the the TDA2003 on a piece of perfboard and atrached lead wires. What are the power supply bypass caps?

 

[Handy Andy]

You can leave them on the main board, just route wires down. Is the TDA 2003 TAB grounded? DO NOT GROUND TO CASE OR CHASSIS - use insulator supplied - verify TAB IS NOT GROUNDED!

As far as hookup , remember Pin 1 on the main board, IS NOT your pin 1 of the TDA2003. Per the YD-1022 Pinout.- refer back to your earlier messages...

Pin 2 of the main board, is your Pin1 on TDA, Pin 3 of Main PCB is your Pin 2 - Pin 4 ON MAINBOARD PCB is skipped, DO NOT USE used on YD-1022, but not on TDA2003.

Now, you have your parings... Pins 5,6 of Main PCB tied to TDA's Pin 3 (Ground) and Pin 7,8 of Main are your Pin 4 on TDA - Pins 9,10 are the TDA's Pin 5 (all 5,6 GND, 7,8 are out and EQ, (EQ routes back thru Pin 2 of TDA) while 9 and 10 are your power feed) - which also has bypass on it but they are now on main PCB. All Main PCB pins are paired except Pins 1,2,3 and 4.

Again verify your work, Pin 1 AND Pin 4 on Main PCB IS NOT USED.

TDA2003 | Main PCB
Pin 1 | Pin 2
Pin 2 | Pin 3
Pin 3(Gnd) | Pin 5,6
Pin 4 | Pin 7,8
Pin 5 (Pwr) | Pin 9,10

You can also install per Message #19 - a POLARITY Protection diode across TDA's Pin 4 and Pin 3 - WITH BANDED END TOWARDS PIN 4 - this prevents a reverse polarity floating ground issue between the output of Pin 4 and the Output cap (470uF) - at this pin is a 1/2 supply rail voltage that if not kept above ground potential can burn up the chip - the YD-1022 already has it installed on the main board - but any heavy modulation can generate a counter EMF "spike" and damage the chip - diode is for that purpose.

You can verify ground by checking locations on Main PCB - where 5 and 6 are - should be foil ground.

And Pins 9 and 10 on Main PCB - are your power and use filter caps.

If you encounter hum or buzz issues, refer to an earlier photo of the 7252AP - its' using a SMD filter cap non-polarized so a Disc 0.1uF to 0.01uF 50V can be strapped across TDA's Pin 5 and 3 ON THE LITTLE PERFBOARD as needed if you encounter "hum" issues.

 

[Handy Andy]

I also have this too...

YD-1022


A lot of extra stuff - that isn't going to hurt the TDA2003 to be there but will impact power...

TDA2003


This is the reason why TDA 2003 is the better choice, now you have plenty of spare parts for other things in life...

 

[Handy Andy]

TO Kaos....



Thank you...

For the rest of us...

TDA2003 has been implemented into their 148GTL design, whether they made/make it or not - since about 2006.

So its been "Coverted" and new component numbering assigned.

:+> Andy <+:

My Research attached...

 

[Larry Pridgen]

Thanks everyone,
Just waiting on some heat shrink paste. I will let you know how I go.
Cheers,
Laz

 

[Fabio GTF]

TO Kaos....

View attachment 24486

Thank you...

For the rest of us...

TDA2003 has been implemented into their 148GTL design, whether they made/make it or not - since about 2006.

So its been "Coverted" and new component numbering assigned.

:+> Andy <+:

My Research attached...

Very good!!!!