I wonder if anyone has a procedure for adding a thermocouple to the core of the MARK IV system.

 

If I recall correctly there were six (6) versions of the Mark* IV released during its product life. In order to modify the input arrangement from factory configuration I believe there were only two of those six that, with knowledge of passwords and access to hidden screens, could be done. The versions in question used Intel 80286 microprocessors, though not all of the Mark* IV versions had the capability to modify the input configuration.

It's been so long since I've worked on a Mark* IV that I've forgotten the passwords and how to access the hidden screen(s). It wasn't too difficult to do, but it can only be done on certain later, as in towards the end of the Mark* IV product life, versions that had the ability to do so.

Prior to these versions of Mark* IV, ALL of the I/O configuration was done by the GE factory in Salem, VA, and could not be modified in the field. The configurations were programmed into PROM (Programmable Read-Only Memory) chips in the factory. Making field modifications to Mark* IV I/O configuration was never anticipated in the beginning of the product's life.

Perhaps if you told us a little more about what it is you are trying to do we can suggest something, BUT we really need to know the age (which corresponds to the version) of the Mark* IV. Honestly, though, without knowing the access password(s) to the hidden screens even if we determine the version of Mark* IV you are trying to modify is capable of making the modification it won't be possible to actually do the modification. I have a couple of former colleagues I could ask for that information but I'm really reluctant to post it to a public forum such as this one.

Have you tried connecting a T/C to an unused T/C input and, after finding the memory address (again, something I haven't done in ages--but wasn't too difficult--just find the Memory Map for your machine, find the signal names for T/C inputs and see if there are spare locations next to inputs that are used (no I don't remember exactly how to access the Memory Map--but it was possible from the Data List menu)), put the memory location in the Logic Forcing display (no; it's NOT possible to force analog input signals to the Mark* IV--you're just using the Logic Forcing Display to monitor the input, even analog inputs can be monitored on the Logic Forcing Display), and see what happens with the T/C connected to the display? (Or use a T/C simulator connected to the "spare" input, set to Type K.)

I wish I could offer more, but that's all I can for now. It's a pretty old turbine control system, and it was a reasonably robust turbine control system, too--especially for its time. Its biggest limitations were the black-and-white CRT, the Alarm Printer (which has been successfully worked around for decades), lack of high speed data acquisition, and the lack of graphic displays. The Auxiliary Display was EXTREMELY useful for troubleshooting some conditions, but the LCD segments commonly failed and couldn't be easily replaced. It was a beast for its time, not the easiest to troubleshoot (getting high-speed data from it was nearly impossible), but when properly maintained it was pretty damn reliable. (I remember one site where leaking lubricating oil, and some diesel as well, made its way to the cable vault beneath the Mark* IV. The Accessory- and Load Compartments also had leaks which allowed very hot air to make it's way into the cable vault as well, which resulted in oil vapors rising up and into the Mark* IV. Eventually the oil vapors starting "dissolving" some of the printed circuit cards in the turbine control panel which made for some very interesting troubleshooting of intermittent alarms and operation.... But, the owner bought a Mark* IV panel which had been removed from another turbine and it's internals were replaced, the leaks all solved (lube oil, diesel, and hot air) and that panel operated well into the 2000's (it was originally installed in the early- to mid-1980s).)

Anyway, if you can describe what it is you're doing and can determine the date of manufacture of the Mark* IV panel (or the version of the panel) someone here might be able to offer some help or suggestions.

 

many thanks WTF?

The MARK IV system in question was installed in 1990 (designed in September 1989);
A thermocouple input for “lube oil manifold temperature” LTH , had already been added by a TA in 1993.

I'm currently looking to add thermocouple inputs to the <C> controller to display load gearbox shaft temperatures ;

The procedure for finding spare part positions is explained in the GEK-83886 service manual; as you said, it can be carried out in various ways, such as the Composite Reals page 0F or the Logic Forcing page 16 (see photo) for example.

It seems that the spare data point addresses IDATA are in the same order as the hardware spare positions.

Connecting a thermocouple for simulation in a spare position following LTH shows no change and displays -18 C° all the time, even though we can rename the new thermocouple and choose its scale identical to LTH (scale 163 for type K T/C); it seems that these unused spare analog inputs have been disabled by design ;

 

@hamid1995,

If someone added a T/C to the panel you're working on then it should be possible to add another if there are unused locations.

I haven't spoken to any former colleagues yet, but looking at the Display Menu and seeing 'Administrative Display' that may be where the input is enable/disabled. But something seems to remind me that there is a special display that is accessed with a code/password to access that display and I just can't remember for certain. SORRY!

I'll ask a former colleague or two; I can't guarantee they will get back to me or how quickly if they do.

 

Which MARK IV system are you using? The DS3800NTCD board is specifically designed for thermocouple inputs. It has 8 integrated circuits, connectors for communication with other boards, and built-in test points for monitoring signals.

 

@hamid1995,

If someone added a T/C to the panel you're working on then it should be possible to add another if there are unused locations.

I haven't spoken to any former colleagues yet, but looking at the Display Menu and seeing 'Administrative Display' that may be where the input is enable/disabled. But something seems to remind me that there is a special display that is accessed with a code/password to access that display and I just can't remember for certain. SORRY!

I'll ask a former colleague or two; I can't guarantee they will get back to me or how quickly if they do.

I'll be grateful if you can found the procedure to activate those spare channels !...

 

Which MARK IV system are you using? The DS3800NTCD board is specifically designed for thermocouple inputs. It has 8 integrated circuits, connectors for communication with other boards, and built-in test points for monitoring signals.

In our case, only one spare channel is activated in DS3800NTCD board, all others are inhibited (showing -18°C during test !)

 

Your supplier can direct you

 

@Dave,

GE long ago (in the mid-to-late 1990s) stopped supporting the Mark* IV turbine control system. They issued an end-of-product life letter for the Mark* IV--which is still in use in many places in the world today--and which resulted in the sale of MANY Mark* V turbine control systems to replace the Mark* IV. (Something similar happened when they released the Mark* IV end-of-product-life letter (those end-of-product life letters turned out to be great sales tactics!).)

There was a rumor that GE Salem sold/transferred the Mark* IV production to BHEL--a GE turbine business associate and turbine packager. I have no idea how many, if any, Mark* IV turbine control panels (or Mark* IV-based turbine control panels) BHEL produced and sold with their turbine packages.

I also know that there was a deal with a Japanese consortium whereby GE transferred most of the Mark* IV turbine control system printed circuit wiring drawings to the consortium as part of a large turbine deal. And, while we all know and appreciate Japanese engineers and designers for their neat and compact electronic equipment the turbine control system they produced was, ..., well, ..., it was ginormous. Almost five (5) times the length and volume of the Mark* IV turbine control system, and it didn't include any synchronization functionality. I was in disbelief when I saw the system, and remained in shock fo a week or so afterwards. It worked, but it was the biggest bit of kludge I have ever encountered. The flame detection section of the control system was as big as two (2) Mark* IV turbine control panels--for four (4) UV flame detectors. (Admittedly, there was a considerable amount of wasted space in that section, but literally there were eight (8) wire terminations from the four (4) UV flame detectors of the turbine in that section.

Anyway, my point is that to my knowledge there are probably two or three people who may be still employed with GE who know anything at all about the even the basic Mark* IV system. I don't have access to any Mark* IV Speedtronic turbine control manuals and there may actually be something in the latest version of the Mark* IV Speedtronic Maintenance Manual about how to access the "hidden" displays, but I don't recall it being in any manual. GE Salem didn't really want anyone other than business associates to know about the capabilities of the "hidden" displays.

I have reached out to a couple of people; one has already responded that he doesn't recall the method for accessing the "hidden" displays--he recalls them, but doesn't recall how to access them. I think it has to be accessed from Data List 20 (which is a way of blacking-out the black-and-white CRT so it doesn't get burned-in from displaying the same display for years/decades) and when keying in the code/password there was no way to know if you made a mistake or not. If you didn't, when ENTER was pressed a new display would pop up with a lot of various options, one of which was, I think, the ability to enable/disable discrete (contact) input channels. Anyway, I'm still waiting to hear back from the other colleague I wrote to.

 

many thanks WTF?

The MARK IV system in question was installed in 1990 (designed in September 1989);
A thermocouple input for “lube oil manifold temperature” LTH , had already been added by a TA in 1993.

I'm currently looking to add thermocouple inputs to the <C> controller to display load gearbox shaft temperatures ;

The procedure for finding spare part positions is explained in the GEK-83886 service manual; as you said, it can be carried out in various ways, such as the Composite Reals page 0F or the Logic Forcing page 16 (see photo) for example.

It seems that the spare data point addresses IDATA are in the same order as the hardware spare positions.

Connecting a thermocouple for simulation in a spare position following LTH shows no change and displays -18 C° all the time, even though we can rename the new thermocouple and choose its scale identical to LTH (scale 163 for type K T/C); it seems that these unused spare analog inputs have been disabled by design ;

Would you care to share the relevant elementary diagrams?

Understandable if you don't.