Panasonic Rx dt9
- Thread starter bigronnie
- Start date
You purchased a japanese domestic model. Very few people imports those because of the reduced FM bandwidth and weird 9khz tuning steps on AM. And there is no 1:1 equivalent form Japanese to non-japanese models, so your chances of finding that transformer and PCB is slim. Your best bet is to rehabilitate that PS and transformer. There's nothing really special about transformers, it just steps down AC to the power requirements of your boombox. Just get a new transformer that is suitable in terms of size and voltage and mounting style, and on the PCB, just replace any electrolytic capacitors (they abhor over voltage conditions) and replace the bridge rectifier or diodes. Then you'll have a regionally correct AC capable boombox. Alternatively, you might have better luck trying to source a similar regional variant. Maybe the RX-DT75? Just be mindful that if you haven't yet checked to see if the boombox itself is damaged, you might discover after going through a lot of trouble that the PS is just the beginning of your problems.
Hey appreciate your response, here it is, other than the transformer, which bits shown need replacing, are they all 100 v relavent
This should retrofit your PS so it can work safely in your area without any adapters. It appears this transformer is a PCB mounted design. They are harder to find but standard Triad F6-12 or Hammond 187D10 might work with some modification on 120v locations, and 230/240 volt versions of those similar ones should be available. You can search the catalogs at Farnell or Newark or Mouser.com or Digikey.com and try to find one that bests matches the size and layout. The actual physical size and wireout specifications can be found by looking at the product datasheets. Remember that the transformers I mentioned above are 120v versions. You should look for similar ones with 230 or 240v primaries. If the new transformer has tabs instead of pins, and they match up with the circuitry on the pcb, you can connect them with paper clips bent and shaped. Paper clips has the thickness and rigidity to hold the transformer down but it's important to make sure they line up, if they do not, do not randomly assign the transformer leads to the nearest pcb through hole. The diodes are nothing special, just get general purpose rectifier diodes that are at least 400v, and it appears these are 1A diodes. The capacitor should be on the secondary side so a 25 or 35v capacitor with the same or higher uf capacity should be fine. I'm not sure if a fuse was originally installed there or not, but if there was and it was blown, get the correct sized one. If unknown, you should check the traces underneath to see if it is protecting the primary or secondary side, it's most likely the secondary side. If it is protecting the primary size, the fuse should only be about 1/4a to 1/2a max. But given that if that was a primary side fuse, those tabs would be high voltage so that is unlikely as the designers would not want to create an unprotected (insulated) hazard on the pcb.
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This is awesome thanks a lot, my stereo takes 10 x Lr20 batteries totaling 15 v, does the transformer need to give an output of the same value 15 v ?
A 12.6vac transformer outputs an "average" of 12.6v AC at the secondaries before rectification. After rectification and capacitor filtered, the peak DCV is going to be around 18 or 19VDC. If you jumped up to the next sized transformer (14.4v), you will get over 20VDC peak. Generally speaking, with a full bridge rectifier and a capacitor filtered output, you are going to get approximately 1.4x the AC secondary output in DC.
By the way, most boomboxes use unregulated power supplies, so that means that the peak voltage will indeed be higher than the normal DC battery equivalent. On use and with a load applied, the voltage will begin to droop. You would expect that the "average" voltage will be approximately your battery voltage. In practice, I have noticed most 15v boomboxes will actually measure about 20-21 volts at the DC rails. This is likely normal for most 15 volt boxes. If you tailor your PS so it outputs 15vdc at the rails when powered with AC, upon a load, the voltage will drop several volts and will probably distort or clip at maximum volume.
By the way, most boomboxes use unregulated power supplies, so that means that the peak voltage will indeed be higher than the normal DC battery equivalent. On use and with a load applied, the voltage will begin to droop. You would expect that the "average" voltage will be approximately your battery voltage. In practice, I have noticed most 15v boomboxes will actually measure about 20-21 volts at the DC rails. This is likely normal for most 15 volt boxes. If you tailor your PS so it outputs 15vdc at the rails when powered with AC, upon a load, the voltage will drop several volts and will probably distort or clip at maximum volume.
Forgive my persistence, this isn't my forte, can this be changed to a 240v? if so could you list the relevent specs of diodes and capacitor for this change. As well as the transformer spec needed so I can order the right one please, I'm not familiar with the jargon used in this field.
Thank you for your patience. Ron.
Ok, we cannot name every component list for what you will need. If you truly are unable to satisfactorily do the substitutions, you should have a local electronics service center repair that PS for you. I already gave you lots of hints and guidance. You have the power supply in front of you, we only have a couple of pictures, and we can't even read the specs on that capacitor since we only see the top. You can easily read it, the specs are right on the side of the capacitor.
Look carefully at the side of the capacitor, it will have a voltage and a microfarad rating (uf). Get a replacement of the same or slightly higher uf rating, and the voltage rating at least as high as the current one, or higher. From the looks of it, it's possibly a 470uf 25v one, but the simplest thing to do is just look at your original and you have your answer.
As for the diodes, I would suggest IN5408 if they will fit. They will be adequately suited.
As for the transformer, that takes a lot of work to do the research because you will need to the physical size (measurements) to ensure the new one will fit. I already gave you FOUR supply companies that sells transformers. The specs are going to be physical size (YOU measure and check to see if your boombox has the space to mount the replacement). The specs are also primary voltage which for you will be 230 or 240V. The specs are also secondary voltage, which I already suggested 12.6V. If you go with 14.4V, your DC voltage after rectification and capacitive filtration is likely somewhere between 21-22V which I think might be too high. Then go to the electronics supply companies websites and search for power transformers. They will list hundreds, and you'll have to match up the specs. You'll have to do that yourself.
Actually if the fuse blew, the transformer might have been saved. You should use a meter to check the primary and secondary windings. If either of the winding is open or shorted, it is blown and unserviceable. If they are not blown, it may be possible that the transformer can be reused. However you will still have the problem of the transformer being the wrong voltage. The same can be said of the diodes and capacitor. I only suggest replacement because they are the most common modes of failure in the power supply suffering overvoltage condition, and it was a way for you to change everything to ensure everything is fresh.
Look carefully at the side of the capacitor, it will have a voltage and a microfarad rating (uf). Get a replacement of the same or slightly higher uf rating, and the voltage rating at least as high as the current one, or higher. From the looks of it, it's possibly a 470uf 25v one, but the simplest thing to do is just look at your original and you have your answer.
As for the diodes, I would suggest IN5408 if they will fit. They will be adequately suited.
As for the transformer, that takes a lot of work to do the research because you will need to the physical size (measurements) to ensure the new one will fit. I already gave you FOUR supply companies that sells transformers. The specs are going to be physical size (YOU measure and check to see if your boombox has the space to mount the replacement). The specs are also primary voltage which for you will be 230 or 240V. The specs are also secondary voltage, which I already suggested 12.6V. If you go with 14.4V, your DC voltage after rectification and capacitive filtration is likely somewhere between 21-22V which I think might be too high. Then go to the electronics supply companies websites and search for power transformers. They will list hundreds, and you'll have to match up the specs. You'll have to do that yourself.
Actually if the fuse blew, the transformer might have been saved. You should use a meter to check the primary and secondary windings. If either of the winding is open or shorted, it is blown and unserviceable. If they are not blown, it may be possible that the transformer can be reused. However you will still have the problem of the transformer being the wrong voltage. The same can be said of the diodes and capacitor. I only suggest replacement because they are the most common modes of failure in the power supply suffering overvoltage condition, and it was a way for you to change everything to ensure everything is fresh.
Thank you so much for your support, a bloke came over to have a look and noticed the cap is cracked on top , he reckons the transformer is safe, ......new cap and fuse