Non working crt

[Pharo]

Hi all I put a post up a few days ago about a jamma cab with a board in it that a fella was wanting rid of so went and seen it as it was only 5 mins away, switched it on nothing on the screen but had sound, I said I would buy the board but didn't want the cab and he said no so walked away, got a message today saying I could have it for free if picked up so went and got it.
Now the questions begin,still nothing on the screen doesn't even seem to be coming on at all so was wondering what I need to look at first, I've added some pics of what make of crt it is and chassis.
Cheers Brian

 

[qjuk]

My guess is that the Hantarex power supply unit is dead. I believe these PSU’s are a common part to fail.
Either way, the chassis is almost certainly going to need a re-cap as well.

 

[Pharo]

Hi thanks for the reply would the jamma board still work as I can hear it and credit it in the cab if the psu is faulty, there is a lit led on it when switched on.
Cheers Brian

 

[qjuk]

Sorry, meant dead as in the part of the PSU that supplies the voltage to the monitor.

It could be something as simple as dry joins inside the PSU.

 

[Pharo]

A that makes sense, what do people use to replace these older psu.
Cheers Brian

 

[tb2000]

It's a Hantarex psu as said and the monitor is a Hantarex MTC900/E. People either fix them up or replace with a separate jamma psu for the game pcb and isolation transformer for the monitor. If you want to check the power to the monitor, looking at it from the rear of the chassis (so you can see the flyback and screen controls) there should be a 4 pin green plug on the left corner supplying it with two different voltages, one pair of wires with 240v for the degaussing circuit and the other pair of wires with 128v for the deflection. Put your multimeter in AC mode and probe the two pairs of wires.

 

[Pharo]

Cheers will look into this tomorrow I gather I do this with everything switched off.
Cheers Brian

 

[qjuk]

You’ll need to power up to check the voltages.

It might be easier to the get your mulitmeter probes into the 4 way connector on the Hantarex PSU rather than try at the green plug end that connects to the chassis.
Pins 1+2 (the red and brown wires) should be around 135v DC
Pins 3+4 (the orange and yellow wires) should be around 230v AC

If the above readings are present then the Power supply is likely to be good and it‘s either the wiring to the monitor chassis or an issue on the chassis Itself.

 

[Pharo]

Cheers thanks for the help appreciate the it.

 

[Pharo]

Hi just checked this at the psu,I'm getting 160 at red and brown and 240 at orange and yellow, disconnected the connector from the chassis and I'm roughly getting the same,so I gather the psu is good.
Anything else I should look at before I see if someone can have a look at the chassis.
Cheers Brian

 

[tb2000]

The 240v pair would be fine for the degaussing circuit, but the other pair putting out 160v is too high for the monitor to work from, they need to be 128v ideally. The voltage range that the MTC900/E can work within is 108 to 141 volts, so that would need addressing.

 

[Pharo]

Hi any ideas what could be causing this or is it a multitude of possibilities as I'm out of my depth with this I'm nearly filling my pants every time I stick my head in to check something 🤣

 

[Pharo]

I gather but could wrong that it's a faulty psu if the voltage is to high and something isn't regulating it, could it be sorted at all.
Cheers Brian

 

[tb2000]

Yeah something wrong with the psu. I'm not that familiar with the Hanty US250 psu so not sure what the cause would be.