Thank you for this video. Yes, my board was blackened in the mains power supply area too. I had to replace the incandescent S-meter illumination bulb & the LCD display illumination LEDs that were out also. The LCD display was darkened & spotty, perhaps by being stored in direct sunlight? The inside was full of bird seed husks. I'm looking at parts donor receivers for a new one. Sometimes if you add an item to the Watchlist, you get a less expensive offer from the seller. We will wait & see. I don't want to dispose of the unit. There is some ESD protection for the 1st RF amp FET & mine was OK. It has plenty of gain. This is a good sounding, sensitive receiver. The rotary controls have a nice, weighted feel. It was a huge improvement over the previous unstable DX-302 & drifty DX-200. The Uniden CR-2021 is somewhat similar. I've seen the Micronta name as a version of this receiver as well. I cannot find a service manual or parts list either. There is a schematic on the last page of the owners manual. I really like your clear & large schematic copy.
How did you blow up the schematic and what printer prints that big? Wow! Also, Radio Shack usually didn't have service manuals as far as I know. They used to always put the schematic on the last page which they stopped doing in the 1990s..... since throw away technology was upon us. Planned obsolescence.
I have enjoyed watching your very informative video. Thanks for posting it and making it so easy to follow. You referred to two MOSFETs, one for FM and one AM, that both sensitive to static damage. I have only hiss on FM and AM and have been using a homebrew active loop (uh 0h!).... do you know the circuits transistor numbers for these? I think I can locate the AM one, but can't quite see the AM one you talked about, above and to the left? I will also replace the electrolytics you replaced on yours while I have the board off. 73 from sunny Devon! Adam M6RDP
It would be good to power the radio using an external DC source. Also, the S-meters tend to go bad in these. You're lucky to have one without that problem.
Maybe it had a cold solder joint, I personally know of a cb radio brand that has one spot that has a cold solder joint that makes the radio inoperable but only takes less time to repair than to open the case. But that's just a possibility
The DX-400 is the same radio as the Uniden CR-2021. Maybe try searching for Uniden CR-2021 and see if a service manual can be found. Did you replace all of the electrolytic capacitors, or just the larger ones in the power supply section? Thanks!
Thank you for this video. Yes, my board was blackened in the mains power supply area too. I had to replace the incandescent S-meter illumination bulb & the LCD display illumination LEDs that were out also.
The LCD display was darkened & spotty, perhaps by being stored in direct sunlight? The inside was full of bird seed husks. I'm looking at parts donor receivers for a new one.
Sometimes if you add an item to the Watchlist, you get a less expensive offer from the seller. We will wait & see. I don't want to dispose of the unit.
There is some ESD protection for the 1st RF amp FET & mine was OK. It has plenty of gain.
This is a good sounding, sensitive receiver. The rotary controls have a nice, weighted feel. It was a huge improvement over the previous unstable DX-302 & drifty DX-200.
The Uniden CR-2021 is somewhat similar. I've seen the Micronta name as a version of this receiver as well.
I cannot find a service manual or parts list either. There is a schematic on the last page of the owners manual. I really like your clear & large schematic copy.
How did you blow up the schematic and what printer prints that big? Wow!
Also, Radio Shack usually didn't have service manuals as far as I know. They used to always put the schematic on the last page which they stopped doing in the 1990s..... since throw away technology was upon us. Planned obsolescence.
I used to work for a company that had A0 printers...
I have enjoyed watching your very informative video. Thanks for posting it and making it so easy to follow. You referred to two MOSFETs, one for FM and one AM, that both sensitive to static damage. I have only hiss on FM and AM and have been using a homebrew active loop (uh 0h!).... do you know the circuits transistor numbers for these? I think I can locate the AM one, but can't quite see the AM one you talked about, above and to the left?
I will also replace the electrolytics you replaced on yours while I have the board off.
73 from sunny Devon! Adam M6RDP
Hi
The 2 transistors are 2SK241GR and 2SK241Y
If you contact on e-mail I can send you the circuit diagram...
It would be good to power the radio using an external DC source. Also, the S-meters tend to go bad in these. You're lucky to have one without that problem.
Maybe it had a cold solder joint, I personally know of a cb radio brand that has one spot that has a cold solder joint that makes the radio inoperable but only takes less time to repair than to open the case. But that's just a possibility
I do have a service manual for the DX-400! Email me--a will cope it to CD.
The DX-400 is the same radio as the Uniden CR-2021. Maybe try searching for Uniden CR-2021 and see if a service manual can be found. Did you replace all of the electrolytic capacitors, or just the larger ones in the power supply section? Thanks!