Arcade monitor chassis removal & repair log

Myrddin

Hi guys, we don't seem to have any pics on the chassis removal procedure, so while doing todays repair I decided to document it.

Here's the chassis itself, it's a Hantarex Polo, & I need to replace the vertical deflection chip on it, after doing a temp repair to confirm the fault.



Ok, to remove the monitor chassis you need to discharge it first. This is absolutely paramount as there are lethal voltages at risk of taking a shortcut through your body in a bid to get to earth. Again, your dealing with potentially lethal voltages here, & never do this if your not sure about what your doing.

To discharge the monitor, I've made up a jury-rigged tool to do the job. A well insulated (thick plastic screwdriver), with three core wire wrapped tightly around the core of the screwdriver, & then insulated with a thick coat of insulating tape. On the other end of the wire, I've twisted all the cores together tightly, effectively turning it into one big wire.



Before doing anything though, isolate the power from the cab, & power it down completely



Disconnect the power connector from the chassis, & the video connector too.



If your screen has an auto-degauss feature, it'll likely have this cable too. Remove it from the chassis



Up in the darkness, the ominous task at hand. I then connected the wire end of my tool to the cab's ground, so just need to touch the screwdriver tip under this rubber cab, & make contact with the anode. This screen auto discharges I think, but I'm not taking any chances. It's good practice to always manually discharge the screen either way.



Making contact with the annode. You normally hear an audible crack when doing this, as the stored energy grounds through the tool. No sound here, but at least I know for sure it's definitely been grounded properly, & am confident to proceed from here.



Anodecap removed, you can see the mechanism that holds it in. It's like a reverse pincher, two little clamps spring outwards & hold the cap securely on the back of the crt. You push either side in with a flat tipped screwdriver to release it when doing so.



Next up is this, the neckboard. They're normally only pushed on, so when removing, pull if off with equal pressure on all sides



Removed, they always feel fragile so just be careful doing that. You don't want to flex the neckboard too much, as there's a lot of circuitry on it also.



Two more connectors towards the rear of the chassis...



That's it for this chassis, it's now safe to remove & work on from here.

Myrddin

Ok, working inside now (thank god, it's a cold shed!), you can see the psuedo repair I had to do. I done this because I wasn't 100% sure of the fault, so had to try a donor chip to be sure. The trouble with the chip was, even though I used a desolder pump, the legs still came out of the pcb all twisted & messed up so there was no way it was going to fit into the where it was supposed to go.

What I had to do was solder wires to where the chip legs normally go, & that gave me some flexability as I could then bend the wires to fit the legs - as opposed to bending the legs. They were quite weak & about to break so bendind legs wasn't an option.

Anway



Wires removed, a lost a track on the chassis too as you can see. I rectified this the same way I dealt with Andrews Amiga..just found where the track was coming from & used a piece of wire instead.



The new replacement chip. This slotted in perfectly.



All soldered up, just the lifted track to deal with.



Bypassed the lifted track



New chip in place...



Thermal paste applied to the back of the chip, & clamped into place with the clamp that was on the old chip



Chassis installed back into place, & all the connectors put back on in reverse order.



Ok now its time to turn the cab on. At this point it's a mixture of taking cover, & crossing fingers...





Success