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Cobra 25 ltd newer version parts help
- Thread starter dss56
- Start date
What you are saying, is that they removed the markings from the pll chip?
Think it should be the same as any late model pll for a 25 or 29?
Think it should be the same as any late model pll for a 25 or 29?
here is the schematic for you to look at. Porkchop gave you the part number.
http://downloads.cobra.com/CB/Models/25-SERIES/New_Version/CobraNew_25_LTD_schem.pdf
http://downloads.cobra.com/CB/Models/25-SERIES/New_Version/CobraNew_25_LTD_schem.pdf
Look on the schematic, home fresh, it’s MX813.
You’ll probabky find that easier than that 2003 part. I had a time but when I did, I bought a small batch. From Canada, eh! Take off eh!
You’ll probabky find that easier than that 2003 part. I had a time but when I did, I bought a small batch. From Canada, eh! Take off eh!
I looked on the schematic for the part number. I haven’t tried looking for the PLL itself. I had to have some of those 2003 audio chips though, they were fun to find. I imagine the PLL might be as well, don’t know.
In my search I found this might be helpful on this site.
http://www.pedrokv.com/radio/navody/cbpllmod.html
TC9106/TC9119
Models include:-U.S.(TC9106)Cobra 18LTD/20LTD/21GTL/ 25GTL/21LTD/25LTD, Craig L104, K40-8, Midland 200M/77-824B, President P220/Andrew J/AR-7/AR44/AX44/AR711/AX711/P200/P210, Uniden PC66/PC33/PC33X/PC55/PC55X/AX-43/PC-3/Pro-540e, GE 3-5804B /5815A/3-5805/3-5804F, Realistic TRC425/TRC426/TRC427/ TRC473/TRC474, Teaberry Stalker III, NDI PC101/PC102
U.K.(TC9119)Audioline 340/341/345, Tandy TRC2000/ TRC2001/TRC2002, Uniace 100/200
These chips use a double ROM set to deny illegal modifications. The only difference between the US version and the UK version are the ROM codes.
No Modifications possible.
http://www.pedrokv.com/radio/navody/cbpllmod.html
TC9106/TC9119
Models include:-U.S.(TC9106)Cobra 18LTD/20LTD/21GTL/ 25GTL/21LTD/25LTD, Craig L104, K40-8, Midland 200M/77-824B, President P220/Andrew J/AR-7/AR44/AX44/AR711/AX711/P200/P210, Uniden PC66/PC33/PC33X/PC55/PC55X/AX-43/PC-3/Pro-540e, GE 3-5804B /5815A/3-5805/3-5804F, Realistic TRC425/TRC426/TRC427/ TRC473/TRC474, Teaberry Stalker III, NDI PC101/PC102
U.K.(TC9119)Audioline 340/341/345, Tandy TRC2000/ TRC2001/TRC2002, Uniace 100/200
These chips use a double ROM set to deny illegal modifications. The only difference between the US version and the UK version are the ROM codes.
No Modifications possible.
I have on order a 9106 pll and hope it is a replacement for the 25ltd pll should have in a few days.
On to my next problem. Same radio its a cobra 25ltd newer version with the TDA2003 audio chip. I did replace the pll with 1 from another radio and radio works so pll bad and 1 is on order.
The problem I'm having is the TX audio and no pa audio.
Radio receives ok no audio problem.
On transmit there is very low audio I have to scream into the radio to get an external modulation meter to move.
I put a radio close to the 25ltd and good signal but low audio.
On the watt/mod meter the watts are around 3 watts but no audio out.
I replaced the TDA2003 with a know good one and same problem low modulation.
So I replaced some caps in the area and also checked some electro/caps most seem good.
Any suggestions board layout and schematic
attached
On to my next problem. Same radio its a cobra 25ltd newer version with the TDA2003 audio chip. I did replace the pll with 1 from another radio and radio works so pll bad and 1 is on order.
The problem I'm having is the TX audio and no pa audio.
Radio receives ok no audio problem.
On transmit there is very low audio I have to scream into the radio to get an external modulation meter to move.
I put a radio close to the 25ltd and good signal but low audio.
On the watt/mod meter the watts are around 3 watts but no audio out.
I replaced the TDA2003 with a know good one and same problem low modulation.
So I replaced some caps in the area and also checked some electro/caps most seem good.
Any suggestions board layout and schematic
attached
I'd look into replacing C47 (inverted feedback loop cap at TDA2003) - and C57 the audio out cap...cheap insurance
But if you get good carrier - when you have to replace the Audio Chip - you usually have to replace what took it out else you'll be right back at it again - usually the audio output cap that goes to the modulation transformer needs to be replaced too, that is usually C57
But if you get good carrier - when you have to replace the Audio Chip - you usually have to replace what took it out else you'll be right back at it again - usually the audio output cap that goes to the modulation transformer needs to be replaced too, that is usually C57
When you have low PA output too - and the RX in the speaker doesn't sound good - usually again, back to C57 - about a 330uF on up to 470uF 25V cap is used you can TRY TO get away with a 16 Volt Rated cap here at C57, but you may wind up replacing that again soon enough.
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