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Tascam DP-004-006 Service Manual.pdf I recently purchased a Tascam DP-006 digital recorder from an Ebay seller. The seller bought it from an Amazon warehouse on a shrink-wrapped pallet of items. I think it must have been a customer return. At any rate, the device is new but will not power up. I tried with AA batteries but got no response. I purchased an a/c adapter with the proper specs and it lights up but behaves oddly. All of the lights come on at once and none of the input controls will function. Also, the display is inoperable/blank. The unit lights up at the moment the adapter is plugged in without pressing the on/off power switch. I am at a loss to explain/understand what is going on here. Also, the power supply plug will lose contact and the unit will lose power when the barrel of the supply plug is rotated to a specific position in the receptacle. I am willing to tear this recorder all to pieces in order to repair (or destroy) it. I would like to understand why it is behaving in such a (seemingly) random fashion and what would have been the likely cause. This recorder cost me nothing and if it cannot be repaired, I am out nothing but my time...and a few headaches.
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Are you sure it the corrcect power supply.
PS P520 is what is called for.
5 Vdc @ 2000ma / tip positive
As there is only a rudimentary block diagram I did take note that the 5 Vdc power goes to a DC to DC converter.
Somehow the power switch turns it on.
The converter may be fried.
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Download the spec sheets for ICs. The power button connects to pin 1 CE (Chip Enable) of the R1223 converter. It seems there may be a number of issues - if the DC connector is working properly the unit should work off batteries. Start at the socket and trace through the DC voltages to make sure the inputs and outputs are correct. Any missing voltage will cause problems. Maybe the original purchaser connected the wrong adapter - reverse polarity or voltage too high.Comment
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I want to thank you for responding to my dilemma. The Tascam adapter is 5+v, 2000mA, center pin +...The adapter I chose was 5v, 2,500mA, center pin +... I checked my adapter to verify the output voltage. It is entirely possible that someone has previously used an ac adapter of the wrong voltage or polarity. If the power supply has been abused in this fashion, would the symptoms described be the result? This device will not power up by battery but will by ac adapter. According to the drawing, battery and ac adapter share the same input line. Also, when it is plugged in (on ac power), all the lights come on and it is unresponsive to any user control input. I did as suggested and downloaded the data sheets for the 3 components in the power supply. I will attempt to take this mini digital recorder apart without breaking any of the critical parts. The Service manual has helpful information (as you posted) but it presumes that the unit is capable of being powered up and able to enter the diagnostic mode. Since mismatched power supplies are likely to be the most common cause of malfunction, I suspect there will be a lot of zombie devices (like mine) that exhibit odd characteristics and cannot enter diagnostic mode.Comment
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Reverse polarity could damage the R1223 DC-DC converter or possibly other components, but you should have enough information to ascertain whether the voltages shown in the block diagram are present. The DC socket switch may be damaged, as the unit will not power off batteries - this may be unrelated to the fault but warrants checking just in case the connector or solder joints to the PCB have been damaged. Losing contact when you rotate the plug also indicates something isn't right and it may be that there's a connection issue that's dropping too much voltage.Comment
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I had an old cassette recorder that I plugged a correct voltage but wrong polarity ac adapter into and it smoked and popped. I think it had a diode in the circuit because the adapter output was ac (not dc like the Tascam DP-006) . I think it might be repairable if I can replace the blown diode and get the proper adapter. This Tascam unit relies on a wall adapter that sends dc into the power section. According to the drawing, the circuit has no protection against an incorrect voltage or polarity being applied. These recorders are sold with AA batteries only. The Tascam wall adapter can be bought and used but it is not included in the recorder package price. Because I was sloppy about my earlier cassette power supply adventure, I am trying to be more diligent about the details. In this power supply, even if I have to replace all 3 of the components, the cost should run to less than $15 shipped. The major price will be the time involved in disassembling (not breaking) , testing, removing, installing and reassembling the unit. By using the term "DC socket switch", are you referring to the off/on switch for the recorder? Thank you all for your help!Comment
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By "DC socket switch" I mean that the DC socket is switched internally to prevent the adapter voltage appearing across the battery terminals. When the plug is inserted the battery voltage is disconnected. If the contacts are not closing when the plug is removed, then there's no voltage to the rest of the circuit. The socket could have been wrenched and damaged, or the solder joints to the PCB broken (very common with DC sockets). Or the battery compartment may have poor contact, or if the unit has wire leads from the battery compartment, one may be broken.Comment
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