Moon Crest electronics questions

[ckong]

Since yesteday I´m the proud owner of a gorcious Zaccaria with one of my all time favourite games playing in it: Moon Crest. ( https://www.dragonslairfans.com/smfor/index.php?topic=3779.0 )

However, at the moment there is still little gameplay, the monitor isn´t working and neither is the game pcb. So here are some questions for you, coming from a complete electronics noob.

Let´s start with the monitor. It´s an ITT A51-211X monitor powered by a Hantarex MTC 90 chassis.



The chassis is powered, I see 5 red lights burning on different places. But there is no neckglow, also no hissing sound or other sound. The only sound that I hear is the soft humming of the transformator. The game pcb is not connected to the connector, so there is no video signal send to the monitor. Should I see neckglow or hear any other sound than the transformator sound?

I cleaned the chassis and monitor today and checked for bad solder joints. didn´t see any. What is the next obvious thing to do?

[level42]

First a small correction:

Let´s start with the monitor. It´s an ITT A51-211X monitor powered by a Hantarex MTC 90 chassis.

You mean: It's a Hantarex MTV-90 monitor with an ITT A51-211X CRT.

Without the game PCB connected you should still see neckglow. Check all the fuses at the bottom of the cab first. Put DVM in Ohms setting and measure all the fuses (of course with the power plug unplugged). Measure while they are still in the holder and touch the holders ( to see if there might be poor contact between the holder and the fuse). Check for any fuses on the monitor itself and do the same.

One warning though, the 90 is one of those "module" monitors.....hard to fix, lots of possible problems...

[ckong]

Yeah, I heard about the notorious MTC 90. I will probably swap it for another chassis, keeping the same crt.

I already checked all the fuses, both at the transformer and those on the MTC 90 chassis. They are all OK.

I did have some progress and a little success. The progress is that I found out that the power board doesn´t spit out 5V. 12V works, 5V not. Will investigate this later, but suggestions where to search for the cause are welcome.

The little success is that the coin door lights are working. A matte of changing the bulbs.  

[ckong]

I decided to swap the ITT A51-211X / MTC90 combo for a 421X / MTC 900 combo, which I first have to build (the MTC900 is now connected with a 231X with heavy screenburn.

About the 211X / MTC90 combo, what should I do with it? Are there other chassis´ with which the 211X will work?

[ckong]

I got the +5V working today. There was no fault in the power board as I first thought, just a bad connection between the one of the fuses and the fuseholder. So I scratched the surface of the fuseholder a bit clean with a little screwdriver, and voila, the PCB connector spits out +5V. So there is a little progress again, +12V. +5V and +6.3V are working.

Now I'm trying to get a good working monitor/chassis combo. I took the A51-421X monitor which came out the electronolo (?) cab (https://www.dragonslairfans.com/smfor/index.php?topic=3764.0) and I found a spare MTC-900 chassis which I had laying around for some years. Before I start fihring questions I should say that I don't even know if they are in working order. I guess we will see.

This is my first time to put a monitor and a chassis together, at least for a classic cab.

1. first question: It's a MTC-900 chassis. How can I tell if it is running on 220V or 128V?
2. if it is running on 220V, then I supposte that I only have to connect two wires from the 220V output of this trafo



to the power input of the MTC-900? I should leave the 128V input for what it is (no connection needed or wanted)?

3. The neck of the monitor has 6 pins. Here the original wiring is still attached



Now I connected the new cable loom at the MTC-900 chassis, but which wire (color) goes to which pin?




Am I correct if I say (judging the MTC 900 manual):

- Yellow (HY) goes to the 5th pin of the left
- Orange (HY) goes to the 4th pin of the left
- Red (VY) goes to the 3th pin of the left
- Brown (VY) goes to the 2nd pin of the left

subquestions:
      - where stands HY and VY for?
      - why are there six pins if you use only four?
      - why has the connector on the MTC900 board 6 pins, but are the middle 2 connected by a wire loop?

4. On the photo above you also see that the two wires coming from the degauss are taped together with light blue tape. Why did they do that and can I leave it like that?

5. what is the purpose of this cable



and do I connect it to this connector (next to the degauss)? Edit: shoot, I just realized that it is the degauss wire running around the monitor.



6. This black cable comes from the neck pcb. I suppose that it is ground and that I have to attach it to the bare wiring on the monitor back, like this:



7. What is the use of th little silver 'box' below the transformator? Is it some kind of filter? What for?



About the original MTC 90 which was in the Moon Crest. It was connected by the trago with 220V (2-pin connector on the MTC 90), but also with 15V and 143V (4-pin connector on the MTC 90). Why all the different voltages? I mean, the MTC-900 gets only 220V (or 128V) input.

One final question: everyring in the cab works on either +5V or +12V, but not the coindoor lights, they work on 6.3V. Why did they do that? Why not use also 5V or 12V for the light bulbs? Because 6.3V was common use?

[level42]

Please Erik, for you own "safety" (or at least, not get confused or get others confused)....use the correct terms when talking about monitors.

First, the main parts:

CRT (Cathode Ray Tube, generally called "tube, or picture tube"):



Deflection Yoke which goes around the neck of the CRT:



Chassis, basically that is all the electronics on 1 or more PCB's:


Frame, some metal set-up to hold all the mention parts above together:


Put all this together and you have a MONITOR.

The tube nrs. typically start with the diameter in either inches (US, f.i. the famous 19VARP4 in the G05 monitors) or centimeters (f.i. A51-421X). This number is almost always on a sticker on the tube itself.

Now I'll read your message and see if I can help

[ckong]

yeah yeah, i know how the parts are called!  It's just late.

[level42]

That is a lot of questions in one go buddy.....

Before you get into all this trouble......wouldn't it be wise to simply hook up one of the NOS WG monitors we got, even if it is just for trouble shooting ?

Thing is, you FIRST need to know if the yoke will match to the chassis.

Not all yokes are the same. There are yokes with a high impedance (resistance) or a low impedance. Put a yoke with low impedance on a chassis that is designed for a high impedance yoke and you will melt the yoke for sure !!!!

So, we need to know:
1) Which kind of yoke does the MTC-900 chassis expect ?
2) Which kind of yoke do you have there ?

You can measure (sort-of) question nr. 2 by using your multi-meter. Put it in Ohms setting and measure between all 4 wires in all kind of combo's and write it down. If you measure infinity ohms (O.L) on meter, then you have a wrong combo.

Two wires are for the horizontal deflection. Two others for the vertical deflection.

The used wire colors look non-standard so the only way is measuring.

Enough for now....

[ckong]

The sticker on the MTC 900 mentiones that it can be used for the A51-421X CRT (and another type that I don´t recall at the moment), but I didn´t thinkt of the fact that the 421X may not have the right deflection yoke on it.

I got a great tip from a forum member which I sure will follow up, nothing beats having the original 211X / MTC 90 combo in Moon Crest.

And in the meantime I may have another solution (poor Vanguard)  and if that does not work, then I will use a NOS WG. Regarding the WG, it runs on 110V, from the trafo, doesn´t it?

[level42]

I'd have to check but IIRC the WG will need 120VAC but doesn't need an isolation transformer....however I have so far only used them behind an isolation transformer simply because it was already there in the cab.

[ckong]

I'd have to check but IIRC the WG will need 120VAC but doesn't need an isolation transformer....however I have so far only used them behind an isolation transformer simply because it was already there in the cab.

What is the difference of using 120V before or after an isoaltion transformer? 120V is 120V, isn't it?

[level42]

Nope. If you hook up a monitor that needs an isolation transformer directly to a mains output (even if the voltage is correct) you get nice fireworks.

[Etienne MacGyver]

MTC 900 has 120 and 220

120 is for the monitor part, the 220 is powering the degauss coil.

[ckong]

Nope. If you hook up a monitor that needs an isolation transformer directly to a mains output (even if the voltage is correct) you get nice fireworks.

yeah, I know, witnessed it once in the past.    But why?

and thanks Etiénne for the info, another question answered.  

Now a fuse question: you know that I live in the rimboe, none decent electronics shop in the neighbourhoud, so it's hard to find the correct fuses. And I need two of them, F 4A, for in the fuseholder after the insulation transformer. I can't find them, but at my work they have S 5A. Is it safe to use those instead of the F 4A?

[polderarcade]

Here I pickup fuses at the local hardware store (small store : hubo)
Don’t know if stores like gamma have them