John's Arcade Forum - Classic Arcade and Pinball Collecting and Restoring Discussion Forum - RETRO MAME - Nintendo Vs Forum

Just getting started on a DK3 machine I found sitting on the curb...

Cleaned it up, plugged it in, get a single vertical stripe along the monitor.  If it was a regular TV, it's got a vertical collapse centered mid-screen.
Got a troubleshooting and schematic PDFs.  Have yet to go thru them.

Question...is an arcade monitor's horizontal, always horizontal?
In other words, if it's mounted so the long axis is up/down, is it still the horizontal, or is it now the vertical?

Disregard...
5 minutes of Google'ing told me what I needed to know.

On to checking pieces/parts...

For furture reference. The top of the monitor is always the side with the annode cup. If a game is mounted horizontally, that means the cup is towards the top of the cabinet. If the monitor is mounted vertically the cup will be towards either the right or the left the cabinet.

If you have HORIZONTAL collapse then you probably don't have a yoke coil plugged in. Its almost impossible for a monitor to ever fail into horizontal collapse.

If you have VERTICAL collapse then there are a lot of things that can cause this. Start with the simplest and check that the yoke wire is plugged in. Next I would check the vertical deflection transistors. which there are between 2 and 4 of them usually. Next suspect would be the vertical drive IC.

I started another thread about the issue.
Turns out the VERT SIZE pot wires broke off causing the single vertical line.  I've likely got a bad C407 on the 16V rail feeding the vertical deflection transistors which is causing the squish I'm getting when I try to maximize the playfield size on the screen.