EBME Forums Forums Maintenance Test Equipment About Timeter RT-200

I got a RT-200 gas flow analyzer,test function is normal.
I want to know if any individual or organization is using it now?If you are still using, please contact me, send an email or post


I disassembled it,and backup 6 EEPROM programs,if there is a failure in the future, please use it for future maintenance,at the same time, I will upload the backup and share it with friends who need it


I see that the microcontroller on the motherboard has been polished,if you know the model number please let me know
By observing the motherboard, I found that it has RS-232 function,I guess it may be used for calibration,you can contact me if you are interested

I hope to increase the functionality of this machine through my own efforts
If you are interested or related questions, you can contact me, thank you

Below is the part of the motherboard I disassembled

Pressure module and flow module

As you know, I am (or at least, used to be) somewhat of an RT-200 aficionado myself (back in the day - late 1980's - some of us used to envy biomeds who had access to this fine piece of test equipment). But perhaps it may help if you gave us an idea about what you are trying to achieve here.

The RS-232 interface was an optional extra. Where installed, the connector to the outside world would occupy slot J-1 as shown at top left of the second image at post #76167 (see also the image posted below).

Slot J-2 was for the IEEE-488 interface connector. The General Purpose Interface Bus (GPIB - originally from Hewlett-Packard) is apparently still often found on test equipment of the "bench" type. I have never seen an RT-200 with GPIB myself. I haven't been able to find an image of an RT-200 with GPIB on line, either.

It would be nice if you could bring these interfaces back to life; as well as - who knows - adding new ones (eg, USB). Apparently, GPIB to USB adaptors are available these days. As well as:- clue.

One of the things I liked about the RT-200 are the opportunities it appeared to offer for expansion. As you know, there are a number of empty connectors on the main board. In this regard I am reminded of 8-bit computers from the same era (especially the BBC Model B and (or) Master). Who knows what use they could be put to!

The design of the RT-200 suggests a "stack", and I have often wondered if Timeter planned more modules. Its predecessor, the RT-100, included a voltmeter and electrical safety tester, and I imagine that the RT-200 could have offered those within another module (I had, at one time, toyed with the idea of adding my own). It would have been nice also to have a module that could handle fluids (for testing infusion pumps etc.). The extra bus connector (see the ribbon cable at top left of the bottom image - the Flow module - at #76169) seems to suggest such possibilities.

As we have found, one of the problems with keeping the RT-200 going (as well as, perhaps, enhancing its capabilities) is a lack of detailed technical information. Connector pin-outs, chip numbers etc. As you have already indicated, this equipment stems from a time when chips were often rendered anonymous! I'm guessing, too, that some of those chips (MCUs) may now be hard to find, and their function may therefore need to be "re-created" in some imaginative way. No doubt you can look forward to many hours of fun!

Lastly, I have yet to hound down any information regarding the DIP switches (S1-S8) on the main board. The manual simply mentions "Programming Switches" (S1-S6 appear to be ON, S7-S8 OFF).

Knowing of your interest, this morning I got in touch with the guy to whom I donated my own RT-200 six years ago. It was a nice clean example (but no J-1, or J-2 interfaces, alas). I was wondering if it was still unused, so maybe I could retrieve it, and then possibly answer some of your questions. Apparently he uses it in some sort of project where he has a need to measure water flow (hopefully, he uses some kind of liquid-to-air adaptor). At least, then, it has gone to a good home!

According to what you mean, I tried to mark the signal points in the figure below. Is this a connection?

About J2，GPIB signal interface I found GND and RX/TX signals,is connected to U9,but this signal definition looks like the definition of RS232 signal,Other signals, such as 8000, A000, B000, 6000 I am still looking for
About J1，Under normal conditions，Short circuit socket,i check 3 wires,but GND was not found,Because based on experience,if it is RS232 signal，at least one wire is directly connected to GND.I do not know why it has to be like this.J2 I'm still looking for a signal,may take time

I cleaned the dust inside the host yesterday,Check various functions after booting,basically normal.
In the next few days,I will try to recalibrate it,Including voltage calibration, pressure calibration, flow calibration...
I will follow the progress steps,update content,take a good note,Share with friends who are still using it
If you have experience in maintenance and use, welcome to share

Rather confusingly, J1 on the main board does not connect to the J-1 ("RS232C") on the back of the unit. Similarly for J2 and J-2 ("GPIB IEEE-488").

In fact J1 on the main board acts as a switch to select EPROM U1 to act as either RAM or ROM.

I'm not sure what J2 on the main board is for, but GPIB (IEEE-488) should have 24 pins.

Looking at your images of the main board, I am undecided whether J3 ("Aux Interface") and J4 ("Interface") or J5 ("Expansion No.2)" and J6 (Expansion No.1") are the ones to dig into for RS-232 and GPIB. I'm guessing J3 and J4.

But it would be nice to get GPIB going, as (presumably) you could then control your RT-200 remotely using the SCPI "language" (Standard Commands for Programmable Instruments; usually pronounced "skippy").

By the way, I notice that chip numbers are still visible on many of the (smaller) chips, but I cannot quite make them out. If you could list them for us, that would be nice. For instance, U8 and U14 adjacent to J2 should give clues to what J2 is meant for.

By checking the motherboard,i found that RS232-C should be connected to J2.I haven't figured it out yet,J2(8000), (A000), (B000)74LS154N output,modern general RS232 three-wire control communication,But it has 7 wires or more
Because I don’t know the U9 model，74LS154N is controlled by U9,Progress blocked,If anyone knows, please tell me the model,I will continue to travel

J1 is only used for reading or writing, only as a switch,Control EPROM writing program or prohibit writing.

GPIB interface,I guess there should be a small board,it connects to J3、J4、J5、J6,input Output,control the machine remotely through the program

I check the pressure module and the flow sensor module,found that the sensor could not find the model,If you know please let me know.I am worried about damage to the equipment,I will back up the pressure and flow sensor test data,Support future damage。scilicet。I will save the pressure value or voltage value corresponding to the flow value.
If you have better suggestions please let me know



Clear picturehttps://ftp.bmp.ovh/imgs/2021/03/0565ee3aa1699c17.jpg
https://ftp.bmp.ovh/imgs/2021/03/233585f3aea6e578.jpg

It looks like you've been very busy!

I notice a couple of intriguing wire links on the underside of the main board.

Re: sensors (and chip numbers); yes, it seems that Timeter were very keen to guard their secrets.

I am also suspecting that a daughter board formed part of the GPIB "package".

On the face of it I disagree with you about J2 being for RS-232, although I don't have the time for any more "research" just now - except to mention that the Signetics 74LS154 (U8) is (was) a "1-of-16" Decoder/Multiplexer (datasheets are available on line).

I have been studying hard I updated the 74LS154 circuit.Since I don’t know the U9 model, I can only enter here

... and U14 (above J2) - MM74HC32N - is a Quad 2-Input OR Gate.

I see a few SN74LS374N there on the main board ... these are basically sets of eight clocked flip-flops; typically used for "driving the bus lines in a bus-organized system"!

OK ... here's another random guess:- it seems to me that U8 is tied to the two main expansion connectors (J5 and J6). I'm wondering if it (U8) is a VIA (Versatile Interface Adaptor); mainly as VIA's used to be popular back in the 1980's (again, the BBC Micro comes to mind). It looks like it may be an Intel device (with forty pins). Could it be the Intel 8255, I wonder?

That's enough for now, as I don't want to be dreaming about this stuff (it's midnight here).