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Cobra 142 GTL
- Thread starter johne2hotty
- Start date
Ive definitely experienced this. Ibstay in the order as listed in the svc manuals.
This is going to sound rude, but it is not intended that way. If you have done this 5 times, the oscillators should not be off by this much. The tripler is off by a whole kHz, gotta wonder why after round 5.
It makes me think that there might be a worn out trimmer or pot somewhere. My daily driver is a washington (same board as the 142) and the trimmers are toast. Still haven't bought any more through hole trimmers, one of these days. Anyhow, I can lightly tap on the chassis and it changes frequency. Do you see sudden jumps in frequency when touching the trim caps or tapping the radio? Does it move more than a few Hz when it gets bounced around a little? Does turning the clarifier when listening to a SSB tone cause erratic tone shifts or does it slide smooth?
It makes me think that there might be a worn out trimmer or pot somewhere. My daily driver is a washington (same board as the 142) and the trimmers are toast. Still haven't bought any more through hole trimmers, one of these days. Anyhow, I can lightly tap on the chassis and it changes frequency. Do you see sudden jumps in frequency when touching the trim caps or tapping the radio? Does it move more than a few Hz when it gets bounced around a little? Does turning the clarifier when listening to a SSB tone cause erratic tone shifts or does it slide smooth?
You should get that sonybond glue out of there. It absorbs moisture from the air and turns corrosive and eats legs off parts.
I can take a look at your settings but if you're conection is slow and the file is large it may be taking a while to load.
73
Jeff
Thanks Jeff. Yeah it starts to upload and at around 15% it just stops. I can upload pics no problem. Pdf is another matter.
Im working at it not that easy. Its horrible andbI have no idea why they just didnt use rtv.
Sonybond adhesive was the go to back then.
I think every major manufacturer used it.
In there defense It's taken 45+ years for the stuff to become the crossive nightmare that it is today.
73
Jeff
For the glue I use a little bit of acetone on a q-tip and apply it directly to the glue. Helps soften it up a bit. Nail polish remover is usually just acetone so you may already have some if you have an XYL in the house. I strongly recommend using it where you can vent the fumes.
I'll also pull parts if it looks like the glue got underneath them. If the glue hasn't eaten a component lead I'll sand off the black crud it leaves and tin the lead before reinstalling the part.
In any case, get as much of that glue out of the radio as you can. Even if it's not the problem today, it will be at some point.
Don't see anything rude there. Lol. I'll bounce it around and see. I did notice a warble in tone when shifting channels and clarifier. The reason why I did this about 5 times is because I had a helluva time with the clarifier when it was unlocked and putting all my money on the 5 volts at L13, then trying to align it so as to get that 10k issue fixed. I was able to get a faint signal by winging it but it wasnt lining up enough to make any real sense. Once I set it straight, i got some stability. It was pissing me off enough for me to take my 10lb sledge to it! But... i didnt. Lol. Only strong signal comes about when its 10k off and even after I put the clarifier back to stock, it still slides over way too much to be normal. Im pretty sure that some other parts were removed and/or put in coils or varactors or removal of disc caps. I cant see anything though. I will have to go part by part through the schematic. Id like to get a factory service manual or a schematic that isnt a sams job. I do see a cut run underneath the 2 crystals that has a disc cap installed. Looks like another hack job. Same as that electrolytic cap from the stack to a resistor that seems to do nothing.
CBTricks.org has the factory schematic, and if you go to the uniden washington section, you'll find a block diagram too.