Author Topic: Panasonic video distribution amplifier teardown  (Read 2272 times)

SeanB

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Panasonic video distribution amplifier teardown
« on: September 19, 2015, 11:47:24 AM »
So, took this to pieces last week, and it has some interesting things inside.

Made by Matsushita, the holding company for National Panasonic, and it has been used since around 1975, making it 40 years old. Video amplifier, with 2 input channels and 3 outputs, which could be either used separately, each with a switchable 75R termination, or as a single amplifier with loop through, with optional 75R termination. Selected via a pair of switches on the back panel.

Inside there is a single power transformer, fully shielded both magnetically with a steel housing and electrically with I would assume a copper band ( from having taken apart similar vintage transformers), with an input that accommodated worldwide use, from 100VAC to 250VAC 50/60Hz. Single secondary of 20VAC to the main board.

There it has a nice Mitsubishi bridge rectifier, and then a main smoothing capacitor, Nippon Chemi Con, with a voltage regulator using a TO3 power device ( made by Matsushita of course) and a hybrid voltage regulator module. Single TO92 transistor is there for the current limiting using the green sense resistor. This gives 24VDC for the  video amplifiers and the single transistor pre amplifiers they have.

The amplifiers are unusual, having a wide 16 pin DIL package with an integrated heatsink on them. Unusual, as they really only have to drive a 50R load. Outputs are AC coupled, using the big blue Mitsubishi ( all the capacitor are Mitsubishi aside from the single Nippon Chemi Con unit on the power supply, strangely) 2200uF 10V capacitors.  The amplifiers are Mitsubishi parts as well, AW2610, date coded 1973.

The case is heavy steel, with a brushed aluminium front panel with a single power switch and a red LED as power indicator, and a latch arrangement which was obviously meant to hold them in a special Panasonic distribution rack, which I do not have.

SeanB

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Re: Panasonic video distribution amplifier teardown
« Reply #1 on: September 19, 2015, 11:58:22 AM »
So, decided to see what was in that 40 year old DIP package, so gave it a little working over with the heat gun, till the epoxy holding the heatsink released.

Underneath I was surprised to find a soldered copper heat slug, and so went a little further with the heat gun to degrade the epoxy case and broke it apart further. Under the heat slug was this small hybrid board, though the removal of the epoxy with a moderate amount of force did have the unfortunate effect of removing the active transistors and diodes with them as well, as they broke off along with the bond wires. All that was left was this ceramic board with thin film trimmed resistors, although you can see the remains of the silicon transistor collectors and the bond wire attach points for them.