| Author |
Message |
    
Rattlesnakejake
| | Posted on Thursday, January 01, 2004 - 2:31 pm: | 
|
Hey guys,
I have finnaly decided against the texas base, and I am going to get a cobra 2000! The guy thats selling it to me says channels one through 14 don't work because some idiot midified somerthing. Do you now a way to fix it????
Thanks sooooo much! |
Crafter
| | Posted on Thursday, January 01, 2004 - 11:04 pm: |
|
Sounds like a PLL problem or maybe he means the way they modified it 1-14 dont work if done that way channel 15 starts at 27.455 and goes up. 1 and 14 stay locked. Does that make sense to ya? |
Crafter
| | Posted on Thursday, January 01, 2004 - 11:04 pm: |
|
Sounds like a PLL problem or maybe he means the way they modified it 1-14 dont work if done that way channel 15 starts at 27.455 and goes up. 1 and 14 stay locked. Does that make sense to ya? |
Dinker1
| | Posted on Friday, January 02, 2004 - 7:24 am: |
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gotta be pll or maybe crystal?????? |
2600
| | Posted on Saturday, January 03, 2004 - 5:06 am: |
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Unless you care about having more than 40 channels, removing the "extra channel" switch wires and restoring the original connections from the channel selector to the PLL chip should fix the problem.
The original PLL chip in that radio is marked "MB8734" and would not provide many extra channels until it gets replaced with a "MB8719" type. If that was done poorly, it could cause trouble, too. If no extra channels are installed, both parts work exactly the same in a 2000.
It is important to unhook EVERYTHING from the radio before messing with connections to the PLL chip. A soldering iron with a 3-prong plug will have a ground connection to the metal tip of the iron. This prevents static-electricity damage to a sensitive chip like a PLL.
If you don't remove the coax and unplug the AC cord, stray current leaking from the tip of an iron with a 2-prong cord can clobber one pin or more on the chip and cause odd trouble like this. Even with a grounded-tip soldering iron, leaving the radio's AC cord plugged in could cause the problem in reverse: stray leakage current from the AC cord can travel to ground through the tip of a grounded iron, and pop the PLL that way.
Unplugging EVERYTHING from the radio is the one way to stay out of that kind of trouble.
73 |
Rattlesnakejake
| | Posted on Tuesday, January 06, 2004 - 3:49 pm: |
|
so your saying if i undid the mod, i could fix it? It just involves rewiring/ no new parts, right??? email me with fullinstructions pizzabobber@earthlink.net |
Crafter
| | Posted on Wednesday, January 07, 2004 - 1:45 am: |
|
How about you e-mail me, kc5djb@yahoo.com
and I'll talk you through it and if need be send photo's of what Im saying and just fix it right. I got a sams manual on the 2000 also, I could probally get copied for ya. Sure comes in handy when setting bias and hunting diodes. Cause Im sure its had every tuner in it turned on time or another! LOL. |
Adshar64
| | Posted on Wednesday, January 07, 2004 - 3:54 pm: |
|
Could be L19 vco tune off and radio locking at ch 15 & up. Easy fix if its this problem .VCO may have beened retuned for higher frequency's at loss of the lower range. |
Rattlesnakejake
| | Posted on Wednesday, January 07, 2004 - 11:39 pm: |
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sound good, thank you all! |
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