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I had another Cobra sitting here from 1995 that had a 2816C in it, and I am still getting the same thing going on at pin 22. I have changed everything from pin 10 of IC1 to pin 4 of IC2, except for L22. I have changed IC2 and no change. I have changed everything from IC 2 pin 6 to pin 22 and...

LC, that is the schematic I've been using. I had no trouble getting a peak reading out of L22 on my scope, the core is about 1/3 of the way down the can. I did change out C94, 87, and 163 previously. I get 5.12Mhz coming out of pin 10 and I get 15.36 Mhz going into pin 4 of IC2, so that...

Sorry everyone, I had MAJOR problems at my house due to the blizzard here in PA!! I finally got around to working on this piece. I changed the 3 caps Exit Thirteen and no change. I had another 7310P that I switched out at IC2 and it made no difference. I still get about 2 Mhz in RX and goes...

Hi Robb, I don't think it's the pll because I'm getting the same frequency coming out of IC2 pin 6 as I'm getting at pin 22 of IC1. I will have to look further at solder joints etc.

Any ideas on the downmix problem LC, Robb, anyone?

I just took the channel selector apart and cleaned it. It was a filthy bugger! Unfortunately got it all back together and same symptoms... frequency messed up at IC1 pin 22, and LED still out,the LED being no concern. Would the goofy frequencies at pin 22 be the reason it's drifting...

OK, here's the scoop. As far as the delta tune goes. R&R in Claymont did the original work on this, and apparently just put an 8.2K resistor in series with D17. The owner of this radio did say it will drift on other the channels too. I did remove the echo from C37 slot and replaced it with...

LC, I have a disc bulging out of my back and can't really do anything today. I can say that I did test TR23 the other day and it was fine. As far as the channel switch, I am thinking that is a problem too. There is a segment out of the LED too. As far as no modulation... this has an echo...

Yep, I sure do Robb. X1 is fine, putting out a perfect 10.24

Hi LC, first off, I am using cbtricks for the service info. Yep, I have 3,2 volts on 40 and about 2.2 on 1. I have 0 volts on pins 20 and 21. and I have 2.4 on pin 22. I asked the guy about the red light and he has no clue. I switched out ic2 with another I had sitting around and the mhz on...

I am working on my buddy's 29, he's having problems with it drifting channels. Sometimes he will lose people on 19 flip to 18 and there they are. I have checked the voltages on the 2816 PLL and they are good. Pin 10 is perfect at 5.12 mhz, pins 12 and 13 are dead on at 10.24. Pin 22 is the...

Ok Robb, I found the gap!! It was C90, a 15Pf cap that fell apart when I pulled one leg to test it. I put a new one in and BAM, everything is up and running! I actually learned a lot just by studying the schematic in the area you guys directed me too. Learning something new every day...

And that would effect the RX too Robb? How do I fix the problem? I am still pretty new to this. Thanks for the help btw!

I checked the voltages on the PLL... All are ok until I get to 10, Pin 10 should be 1.9 RX/TX Actual is .8 Pin 15 4.8/4.8 is 0 Pin 16 4.9/4.9 is 0 Pin 17 1.8/1.6 is 0 Pin 18...

That's what I use to align Cobras Robb. Channels 1 & 40 both come in at 4.3 volts. Adjusting L19 does nothing to change the voltage. For that matter, step 1 & 4 isn't working either.

I have a scope and I have no rf signal at all. Like I said my VCO voltage is 4.3 on channels 1 and 40, don't know if the problem is somewhere around there or not, I am still learning here. I checked the voltages on IC1 and I noticed some channels I will have the proper voltages at pins 1, 4,5...

I don't think it's that LC only because I had proper voltages on IC1 and IC3, which now I don't have, I had a carrier and modulation and then after a few minutes nothing, When I checked the voltages they were not where they were before, so I think something else took a dump for some reason.

I pulled the 1969 and put a 2078 in it's place. I had it working but it suddenly quit transmitting when I started to align it. I checked the voltage at TR23, the regulator, and they are good. I check the voltage on IC1 and have no voltage until I get to pin 7. I should have 4.9 at pins 1, 4...

BTW, RX and PA work great.

I have a really nice Phillipine 76XL that had no carrier or modulation. I tested the driver, 2sc1957, that was bad. I don't have any so I figured I would throw in a 2314 driver and 1969 final. BTW, the final that was in there was a 2029. After putting these in I still had no carrier or...