Nihon Kohden crt monitor, scrap it or not? - Page 1
Forum section: electronics / general

author: muvideo
author_rank: Frequent Contributor
timestamp: June 02, 2012, 03:46:46 pm
content: Hello, I had this monitor from some time, it was part of a medical device thatwas full of boards, it provided heart rate, respiratory info, and other things.The boards are from late 70's, it was scrapped and I extracted the boardsmany years ago.What remains is this nice scope-like monitor:these are the controls, it has two channels:let's open it, from behind on the left there is the board that connects to external world,from there pass the supplies and the signals, inside on the left there is the "backplane",a board that connects the amplifiers and the sawtooth generator; on the right there arethe power supply boards: a low voltage preregulator, a medium voltage board and thehigh voltage transformerA closeup of backplane, we can see the needed voltages written on it:This is the side, there are the power supply boards, and the side of the crt,this one is slightly unusual: it is an electromagnetic deflection device, withvector output, pratically a slow cheap oscilloscope.this is the preregulator, it generates +12 -12 and +5V from tree inputvoltages, I used simply +-18V to power it up, the NEC I4305 and I4312seem Nec's 78xx equivalents, they are boosted by a pair of transistors,should be 2SB512 and 2SD389, are current limited by the 0,47ohmpower resistors and small transistors:more to follow...

author: muvideo
author_rank: Frequent Contributor
timestamp: June 02, 2012, 03:48:54 pm
content: Medium voltage supply, this and the HV board generates the voltages neededby the crt from the +12V line:this is the back, not very clean:and these are some strange diodes, never seen with this package,a plastic bathtub with a drop of sealant on top:These are 3 boards that connect to backplane, I'v yet to check them, I'dlike to undestand better how are generated and painted the two channels,I suspect that it's like a scope's chopped mode:These are the two traces, slow scan and long persistence the CRT isa NEC with the markings C543P7 901 003, on the deflection coil YS-0706-160 XFAA:I'll play a little with the boards, but I dont knowwhat to do with it,I like the slow crt/high persistency.Any proposal is welcome, I was thinking to something like a low frequencynoise or temperature monitor, or something similar.Fabio.

author: T4P
author_rank: Super Contributor
timestamp: June 02, 2012, 04:16:04 pm
content: Maybe they added the plastic bathtub for better heat dissipation ?

author: SeanB
author_rank: Super Contributor
timestamp: June 02, 2012, 05:25:31 pm
content: I have some similar mecical equipment, but these use Tektronix scope units. One has a simple screen, medium persistence phosphor, while the other has a microchannel plate storage screen. The medical side electronics are long dead, but the onr scope i know works, i was considering making a curve tracer out of it some day, it is small enough and good enough to do so.

author: T4P
author_rank: Super Contributor
timestamp: June 02, 2012, 06:06:28 pm
content: OT : Looking at modern medical equipment is far more ... epic then looking high end scopes ...i mean like i was at a hospital's coronary care unit and was staring at the philips medical 'scope' ... 19" with a really sharp display

author: muvideo
author_rank: Frequent Contributor
timestamp: June 02, 2012, 06:16:36 pm
content: Quote from: SeanB on June 02, 2012, 05:25:31 pmThe unit I have is the last remain from a pile of medical devices scrapped many years ago.I scrapped all the things I though were not interesting or too time consuming to make something, they occupiedtoo much space in the lab. I scrapped other monitors, but salvaged this because seem very simple to connect to,and other interesting or strange bits (as soon as I'll find some cheap laser pointer I'll make a post about something involving high voltage, vaccum devices and laserusing an old device coming from these things).Probably the curve tracer is a wonderful idea to do with a slow (or memory) tube, how hard would it be to do?I'll search the net for more info.Quote from: DaveXRQ on June 02, 2012, 06:06:28 pmOpening old medical equipment was something very interesting for me, the things I dismantled where from old tovery old, from late '60 to first '80, and there was one thing clear: the cost was non issue.The old things were also wondeful mechanical devices, I still have somewhere small dc motors with all sort offeedback from tachimetric generators to optical to syncro resolvers.Fabio.