MODIFICATIONS
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DENON DP-61F
UPGRADES and MODIFICATIONS






  • This Denon DP-61F turntable has been in my family since bought new around 1985. One of Denon's better models it was seldom used since 1995, maybe once a year during the holiday season. Recently I dug it out of storage but found some problems when I powered it up: the power light lit, but the platter wouldn't spin when the arm was moved. The red platter light in the rear was out too. Seemed dead.

  • I really wanted to salvage this TT and worried the problem was something impossible to fix. But I had heard several success stories from people who had resurrected theirs by replacing the ancient electrolytic capacitors. So I decided I had nothing to lose. Here's how I did mine.

  • First, remove the metal platter so it wont fall out and break anything...be careful not to touch or scratch the brown magnetic strip on the inner edge. Clamp the tonearm and make sure the counterweight won't fall off. You should also remove the cartridge so it won't get damaged. I then turned the whole unit over, with dust cover in place, onto a large soft towel. The TT is heavy and you have to take extra care here not to stress the rear hinges on the dustcover...you don't want to snap them off. Then simply remove all the small wood screws around the outside edge of the bottom. The bottom lifts right off.

  • INSIDE THE UNIT
    In the DP-61F there are two areas to concentrate on: the power supply and the main board. Leave the arm mechanism alone.
  • For standard circuits not in the signal path I like to use Nichicon VR electrolytic capacitors. They are high quality "general purpose" caps with a neutral sonic signature and are perfect for circuits requiring stability. In circuits that touch the audio signal like on amps and preamps I like the Elna Silmic and Nichicon FG (for higher voltages) and PW on the power supply. For my purposes here I stayed with the VRs.


  • Gaining access to the underside of the power supply is very simple. Just remove the screws in its corners and the board will lift upwards. There are two 2200uf 25V electrolutics. I replaced mine with the same value VRs. Kind of funny how much smaller modern caps are in comparison. There's no need to upgrade the other ceramic/film caps or resistors on that board.

  • To gain access to the main board remove all visible screws. You'll notice a hidden screw under the bottom board edge where the power light is...remove that bracket. The board will then swing upwards towards the motor. There's no need to unsolder any wires but be careful not to stress them. You'll need to find a way to support the board so it sits on the edge like below.



  • There are about 45 electrolytics scattered about the board...most are 1uf, 4.7uf, or 47uf coupling caps. I suggest you open a spreadsheet and spend some time writing down all the values you see. Remember that none of the caps are in the signal path so ignore all the tan ceramic caps on the board...no need to be paranoid or replace those, they should still be accurate.

    For replacements I ordered the identical microfarad values but in the case of 10V ones I upped them to 16V to add some voltage capacity. These small caps are so cheap I ordered a few extra of each value in case I made a mistake in counting them on the board.

    IMPORTANT: My board was marked with a + for each cap. But before you begin take a few closeup photos so you can remember the value of each. If you get distracted while resoldering it's easy to make a mistake and forget where you were.

  • I didn't have any problems with unsoldering them. I have a 40-watt iron and quick touch on the leads let me pull the old ones out. Most of the eyelets cleared out by scraping the iron across them. So I was able to quickly solder a new cap in place with no fuss or lifting of the tracing.

    Doing one cap at a time and double-checking the polarity before moving on was the key. It took me about 45 minutes to do the entire board. The last step was to replace the foam square on the bottom of the motor. Mine was soft and disintegrating. I think it might have been a primitive noise damper. I created a new replacement from some foam I had.

    RESULTS
    After putting everything back together and bolting the case back up...I plugged it in and pressed the power button. The red platter light on the rear now came on (!) Next I moved the arm out over the platter and after a moment I heard a hum and the platter spun up to 33RPM. Nice.

    I put on both a 33 and 45RPM record to test. The needle dropped on the lead-in grooves perfectly, and came off at the end in perfect spot. The arm tracked back to its rest. Everything seemed to work perfectly. I could almost sense the circuit was happy to be energized once again.

    To find the culprit I took my multimeter and spent a few minutes checking capacitance on each of the caps I pulled out. All of them spec'd out except for one: when I measured it the Fluke showed overload and couldn't get a correct value, I believe it was shorted internally. In checking the schematic it was a critical coupling cap in the motor circuit. Changing out all the other caps probably didn't hurt either.

    So I cleaned up the TT and used some lemon oil on the rosewood base...recalibrated the Denon DL-160 cartridge and set the tracking force. Connecting it to my preamp I was treated to an ultra-quiet noise floor on a new album I had...excellent imaging. I thought of replacing the old RCA cables but that requires unsoldering them from the arm mechanism. Maybe another time.

    What an inexpensive, fairly simple, and satisfying update to an old piece of equipment.

 


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