Magnum Dynalab Etude tuner recap

Rear view of the unit.  Antenna input to the left, WBT RCAs at the right, XLRs for balanced output barely visible below those.

The unit as received.  It was working well, but I decided to re-cap it to ensure a long life.

The Etude version is primarily an audio upgrade, including WBT RCA connectors and the large black Solen coupling capacitors (polypropylene) on the upper left.

The PCB above those caps is for the balanced outputs and feeds the XLRs below the RCAs on the rear panel.

A better shot of the output coupling caps (and the inside of the WBT RCAs) and the balanced output board.

Closeup of the front left side of the main PCB.  The white rectangle on the right is the output IC, painted over to cover its markings.  More on that later.

In order to replace parts on the main PCB, it needs to be lifted up.  Due to the large number of wires on the front of the PCB, I decided to disconnect all of the wired connections to the rear panel to allow lifting the PCB from the rear.

This shows the antenna input, the first wired to be disconnected.

TIP: before beginning any dis-assembly, take lots of photos to document things before you start.

This shows the WBT RCA jacks, next to be unsoldered.  Below those (but not visible here) are XLR balanced outputs, also disconnected.   Also shown here near the top is the composite output BNC connector to be disconnected.

The AC power line was also disconnected from the PCB.

Once the rear panel connections are disconnected, the main PCB was unscrewed and lifted from the rear, as shown here, to allow working on the PCB.

I taped a block of wood to the board to hold it steady in position while I was working on it.

This PCB has lots of very heavy traces, so I found a large soldering iron tip (1/8") and high temp (800 degrees) worked best.

I planned to replace the output IC with a socket to allow trying various ICs.  After removing the original IC, I found the white paint was easily removed with a bit of isopropyl alcohol.

As you can see, the chip is a Signetics NE5532 (dual IC).  

After installing the IC socket, I replaced it with an OPA2604 thats sounds fine.

Tuner expert Don Scott (RIP) modified a similar tuner some time ago and recommended replacing the 12 volt regulator with an LM340-12, along with a heatsink.  He felt that significantly reduced warm-up drift in the unit. 

This shows the new regulator and heatsink before installation.

This shows the audio output end of the PCB after the new electrolytic caps were installed.

I used Panasonic FC 105 degree caps for almost all replacements.  I counted a total of 22 caps that were replaced.

You can see the new regulator & heatsink at the bottom of this photo, and the new OPA2604 IC and socket on the left.

With the heatsink, the regulator gets just warm to the touch.

This shows the updated unit "after" re-assembly.

Without careful observation, it looks almost identical to the "before" photo at the top of this page.

Updated unit, looking exactly as it did before the work.