Siemens Echo Encephalograph Teardown

In early 2012, I bought a very peculiar machine from a friend, who bought it from the junkyard. After looking inside, there were some seriously damaged circuits, so I thought it was not worth restoring it. The best decision was to tear the machine down to reuse the – extreme good quality – parts. I took several photos of the process, but I will only publish the best ones.

Completely dirty.

Full of dust and dirt.

The leather handle is not in very good conditions.

The leather handle is not in very good conditions.

Things I found lying inside: a broken tube, a 6AQ5 tube (not related to the machine), a battery, a screw, a washer and a pin.

Things I found lying inside: a broken tube, a 6AQ5 tube (not related to the machine), a battery, a screw, a washer and a pin.

Here you can see a huge crack on the PCB.

Here you can see a huge crack on the PCB.

It was very late, so I left everything for the next day.

After serious cleaning, it looks like a new machine, and the text is readable.

After serious cleaning, it looks like new, and the text is readable.

Translation:

  • Netz: Power (on);
  • Schärfe: sharpness (focus);
  • Nullpunkt: Null point (center);
  • Masstab: Scale;
  • Prüfbereich: Test area;
  • Impulsstärke: Pulse strength;
  • Tiefenausgleich: Deep balancing;
  • Verstärkung: Amplification;
  • Skalenbeleuchtung: Scale lighting (a rheostat to adjust the brightness of lamps that light the scale);

Close-up of the stylized text and input connector.

Close-up of the stylized text and input connector.

Main board, right section. The black box with the tube is a high voltage generator for the CRT, and the only part that was intact and I managed to make it work.

Main board, right section. The black box with the tube is a high voltage generator for the CRT, and the only part that was completely intact and I managed to make it work (the CRT is intact also, but I never was able to test it).

An interesting feature is that the two main boards have hinges. All the tubes have aluminium caps, to avoid high frequencies from one tube interfering the functions of another, and vice-versa.

An interesting feature is that the two main boards have hinges. All the tubes on these boards have an aluminium shielding, to avoid high frequencies from one tube interfering on the functions of another, and vice-versa.

Left to right: E 130L, AG5121, E80cF, E83F, E188cc.

Left to right: E 130L (power beam tube), AG5121 (gas filled thyraton, works like a SCR), E80CF (triode-pentode), E83F (pentode), E188CC (double triode).

Close-up of the high voltage generator. It's a common flyback oscillator setup.

Close-up of the high voltage generator. It’s a common Hartley oscillator setup.

Another close-up of the right board.

Another close-up of the right board.

Back side.

Back side.

Calibration in cm.

“Calibration in cm”.

Main board, left side section. The upper board is (probably) the power supply, as it has a bridge rectifies (hybrid technology!) and some filtering capacitors.

Main board, left side section. The upper board is (probably) the power supply, as it has a solid-state bridge rectifier (hybrid technology!), a 150B2 voltage regulator tube, and some filtering capacitors.

This board (probably) houses four HF oscillators, judging by the presence of adjustable coils and the low value, silver mica, capacitors on the other side.

This board (probably) houses four HF oscillators, judging by the presence of adjustable coils and the low value, silver mica, capacitors on the other side.

Shielding removed.

Shielding removed. Left to right: E188CC (double triode), 5*E83F (pentode).

The said filtering capacitors, and a board covered in some kind of wax, to avoid arcing.

The said filtering capacitors, and a board covered in some kind of wax, to avoid arcing.

Close-up of the solid-state rectifier, and the CRT shielding.

Close-up of the solid-state rectifier, and the CRT shielding.

Upper side: Two EL84's at the power supply board.

Upper side: Two EL34′s at the power supply board.

Front cover removed, showing the scale and it's lighting system.

Front cover removed, showing the scale and it’s lighting system.

One of the boards after being removed. Here you can see that the crack goes the whole board, one side to another.

One of the boards after being removed. Here you can see that the crack goes through the whole board, one side to another.

DSCI1044

Power supply board. Left to right: 2*EL34 (pentode), E80F (pentode), 150B2 (voltage regulator).

DSCI1056

Oscillator board. The missing tube is probably the broken one.

DSCI1064

Tiny board full of resistors, and two capacitors.

The power supply transformer, weighting about 4kg(!). The metal box houses a filter, to avoid interference from the mains grid.

The power supply transformer, weighing about 4kg(!). The metal box houses a filter, to avoid interference from and to the mains grid.

DSCI1058

Transformer wiring detail.

I was not going to add this pic, because the focus is terrible here, but reading "Made in W. Germany" is somewhat funny nowadays.

I was not going to add this pic, because the focus is terrible here, but reading “Made in W. Germany” is somewhat funny nowadays.

Then it gets pretty boring: I removed the tubes from their sockets, desoldered everything else and stored the parts for later usage.

After searching the web for information about this equipment, I could only find these:

2 Responses to “Siemens Echo Encephalograph Teardown”

  1. I have an oscilloscope from the late 60′s, and allthough it uses tubes, it also uses some solid state resistors. It’s interesting to see these old PCB’s where it looks like components are just thrown about.

    BTW, that one link is in Norwegian, not Swedish.

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