TEC-1700K teardown - Page 1
Forum section: electronics / testgear

author: brutester
author_rank: Contributor
timestamp: April 08, 2015, 12:07:07 pm
content: I've been watching Dave teardown equipment so many devices, so I've decided it is time to open my lab power supply and send some photos.Some background: TEC (that's in cyrillic) power supplies were developed and manufactured in Bulgaria (http://en.wikipedia.org/wiki/Bulgaria) during the 1970s and 1980s. In that era Bulgaria was part of the Eastern Bloc. All industry was owned and controlled by the state. In 1982 Bulgaria have started to develop and manufacture a clone of IBM PC, known as Pravetz. The country needed a lot of electrical engineers to be trained, so they've open classes in many schools and universities. To ease the lab training they've developed a the TEC-1700K lab supply.TEC-1700K has six fixed power outputs and a voltage and current controlled one. The outputs are:+5V/2A ; -5V/1A+12V/1A; -12V/1A+15V/1A; -15V/1A(0V to 36V) at (0A to 1A)All outputs are active simultaneously. Each one has overcurrent protection.Fixed outputs share a common ammeter, that is switchable using the six buttons above outputs.Controlled output has voltage and current meters. There are two rotational potentiometers for coarse setting of voaltage and current. The are are two potentiometers for fine setting that can to be turn by using a screwdriver.Inside the unit there is a big transformer, some power diodes and transistors that are inside the aluminium case, and 8 PCBs. Total weight is around 10.5 kg.4 of the pcb's look the same. I suppose that they are used for the outputs and the big aluminium cased potentiometers are used to tune them for +/- 5/12/15 volts.All elements are using USSR nomenclature IDs. They look pretty standard for the era.

author: brutester
author_rank: Contributor
timestamp: April 08, 2015, 12:08:00 pm
content: More pictures

author: brutester
author_rank: Contributor
timestamp: April 08, 2015, 12:08:32 pm
content: And more pictures.

author: Vgkid
author_rank: Super Contributor
timestamp: April 08, 2015, 03:01:39 pm
content: Thanks tor the teardown. I was surprised to see multiple circuit hoards.

author: rollatorwieltje
author_rank: Unknown
timestamp: April 08, 2015, 09:02:40 pm
content: Image 6440: looks like they decided on fitting a metal can IC instead of a dip package. Fun fact, the Soviets used a different pin spacing of 2.5mm instead of 2.54mm.

author: brutester
author_rank: Contributor
timestamp: April 08, 2015, 09:55:06 pm
content: Quote from: rollatorwieltje on April 08, 2015, 09:02:40 pmThose metal can ICs are the solviet equivalent of uA741. Don't forget that this was produced during the cold war, so the engineers had to use parts produced in the Eastern bloc, with their casings. Most of the elements have very big dimensions. For example the big aluminim cased caps on picture 6428 are 120mm wide with diameter of 50mm. They are produced in Eastern Germany. The big shunt resistors (0.51Ohm +/-1%) on picture 6443 are 50mm wide with diameter of 10mm. The calibration potentiometers (aluminium ones on same picture) are like 50x10x10mm and they are only 10kOhm. Today you have the nice blue potentiometers, that are 8x8x2mm.Btw, I've forgot to write the dimensions of the unit - 420x350x120 mm DxWxH.