Cobra 2000 GTL S/N 65001008 Refurb Project Log
Posted: Jul 25 2020, 08:05
Serial No: 65001008
Made in: Taiwan
Year on MB8734 PLL chip: 1986
Extension speaker: 1 x CA-2000
Mic: CA-72 Dynamike
Objective: To restore this rig to as close to original as I can.
Purchased from an eBay seller in 2018 who sold it as Not-working/Parts to cover himself.
However, when I contacted him about it he said it used to work but he was no longer in a position test it on air so could not guarantee it.
He wasn't lying about operational condition; it does work on the bench. It receives signals from a close-proximity, low-power handheld without an antenna plugged in, and according to my meter puts 4 watts AM and 12 watts SSB into a dummy load.
The eBay photos looked reasonable. It was bit of an ugly duckling thanks to a pretty ordinary job of matte black skin glued to the face plate and speaker.
It was advertised as unmolested, which is what I was seeking. While essentially true, it's clear that someone along the line of ownership since 1986 has been at it, for better or for worse.
Condition and Issues
Top metal cover: Somewhere along the line of ownership, the original top metal cover has been replaced by a sheet of what appears to be perforated steel speaker grille material. I'd love to get rid of that for an original cover, but it's low priority at this stage.
Sony glue: Seems to have been largely cleaned of the dreaded brown corrosive and conductive goop at some stage. I did find some remnants and got rid of them with acetone.
Face plate: I removed the horrible matte black skin hoping the the original silver would be in good enough condition. It wasn't. The silk screened markings were worn in places and there were scratches and divots in the metal that could not be overlooked. So, I purchased a silver skin kit online and attached that. I was hoping to find a matte version, but could only find shiny chrome. It looks pretty respectable now.
Knobs: As expected, some of the knobs were not original. I have since sourced original knobs.
Channel switch: the channel display showed hieroglyphics on about 12 of the 40 positions. A few judicious squirts of contact cleaner into the back of the channel switch fixed that.
Channel display window 'glass': The plastic window 'glass' which shows Mode, Receive and On Air is in poor condition for two reasons. The glue that holds it into the face plate has gone to liquid and filled the cavity between the front and the purple colored filter that sits behind it. That's not so bad, but the green plastic filter for the Mode lights (LSB/AM/USB) has been distorted and discolored by the wheat bulb that lights for AM. Clearly, someone favored AM and it appears that a too-high power wheat bulb has been put there at some time and burned the filter black so that no light comes through when on AM. Then, in an attempt to clean it, they have scratched the back of the plastic destroying the AM and LSB printing. Action: After quite a bit of searching, I have found a guy who will sell me those bits from a rig he is parting out.
Lamp rubbers gone hard: I was mulling over whether or not to upgrade from wheats to LEDs. As above, my desire is to have this rig as original as I can get it so I was prepared to chase some wheat bulbs until I saw how baked and distorted the bulb rubber grommets had become from the combination of heat and age. Some are rock hard and crumbly, so that deiced me on a set of white LEDs. (I am not a fan of colored LEDs). I am awaiting delivery of those. ( After installation, I may then have to deal with the well known channel number ghost effect due to residual voltage when the rig is powered off via the front switch.)
Meters stuck: Par for the course. I should be able to fix those in the usual manner.
Headphone socket: Someone has completely removed the wiring from this socket. Why ???
Not only is the socket sitting there naked, none of the original wires are anywhere to be found. Incredible!
Electronics: It hasn't been re-capped, but some of the usual suspect electrolytics have been replaced. The power supply filter capacitor has been upgraded to 15000uF 35V. Oddly, a choke (ETP 7620053) has been mounted to the top of the cover of the frequency counter/clock enclosure. It's in series with the 13.8 volt DC input socket. Maybe someone had this rig in a vehicle at some stage, or connected to a crappy DC source, and it's some form of noise suppressor. The heat sink grease is pretty dry and could do with refreshing.
So, that's the situation as at the time of writing. As with most projects, it's the waiting on parts that drags them out.
Made in: Taiwan
Year on MB8734 PLL chip: 1986
Extension speaker: 1 x CA-2000
Mic: CA-72 Dynamike
Objective: To restore this rig to as close to original as I can.
Purchased from an eBay seller in 2018 who sold it as Not-working/Parts to cover himself.
However, when I contacted him about it he said it used to work but he was no longer in a position test it on air so could not guarantee it.
He wasn't lying about operational condition; it does work on the bench. It receives signals from a close-proximity, low-power handheld without an antenna plugged in, and according to my meter puts 4 watts AM and 12 watts SSB into a dummy load.
The eBay photos looked reasonable. It was bit of an ugly duckling thanks to a pretty ordinary job of matte black skin glued to the face plate and speaker.
It was advertised as unmolested, which is what I was seeking. While essentially true, it's clear that someone along the line of ownership since 1986 has been at it, for better or for worse.
Condition and Issues
Top metal cover: Somewhere along the line of ownership, the original top metal cover has been replaced by a sheet of what appears to be perforated steel speaker grille material. I'd love to get rid of that for an original cover, but it's low priority at this stage.
Sony glue: Seems to have been largely cleaned of the dreaded brown corrosive and conductive goop at some stage. I did find some remnants and got rid of them with acetone.
Face plate: I removed the horrible matte black skin hoping the the original silver would be in good enough condition. It wasn't. The silk screened markings were worn in places and there were scratches and divots in the metal that could not be overlooked. So, I purchased a silver skin kit online and attached that. I was hoping to find a matte version, but could only find shiny chrome. It looks pretty respectable now.
Knobs: As expected, some of the knobs were not original. I have since sourced original knobs.
Channel switch: the channel display showed hieroglyphics on about 12 of the 40 positions. A few judicious squirts of contact cleaner into the back of the channel switch fixed that.
Channel display window 'glass': The plastic window 'glass' which shows Mode, Receive and On Air is in poor condition for two reasons. The glue that holds it into the face plate has gone to liquid and filled the cavity between the front and the purple colored filter that sits behind it. That's not so bad, but the green plastic filter for the Mode lights (LSB/AM/USB) has been distorted and discolored by the wheat bulb that lights for AM. Clearly, someone favored AM and it appears that a too-high power wheat bulb has been put there at some time and burned the filter black so that no light comes through when on AM. Then, in an attempt to clean it, they have scratched the back of the plastic destroying the AM and LSB printing. Action: After quite a bit of searching, I have found a guy who will sell me those bits from a rig he is parting out.
Lamp rubbers gone hard: I was mulling over whether or not to upgrade from wheats to LEDs. As above, my desire is to have this rig as original as I can get it so I was prepared to chase some wheat bulbs until I saw how baked and distorted the bulb rubber grommets had become from the combination of heat and age. Some are rock hard and crumbly, so that deiced me on a set of white LEDs. (I am not a fan of colored LEDs). I am awaiting delivery of those. ( After installation, I may then have to deal with the well known channel number ghost effect due to residual voltage when the rig is powered off via the front switch.)
Meters stuck: Par for the course. I should be able to fix those in the usual manner.
Headphone socket: Someone has completely removed the wiring from this socket. Why ???
Not only is the socket sitting there naked, none of the original wires are anywhere to be found. Incredible!Electronics: It hasn't been re-capped, but some of the usual suspect electrolytics have been replaced. The power supply filter capacitor has been upgraded to 15000uF 35V. Oddly, a choke (ETP 7620053) has been mounted to the top of the cover of the frequency counter/clock enclosure. It's in series with the 13.8 volt DC input socket. Maybe someone had this rig in a vehicle at some stage, or connected to a crappy DC source, and it's some form of noise suppressor. The heat sink grease is pretty dry and could do with refreshing.
So, that's the situation as at the time of writing. As with most projects, it's the waiting on parts that drags them out.
