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Main => Monitor/Video Forum => Topic started by: Popcorrin on March 16, 2006, 09:52:48 am

Title: Dead Wells K7000
Post by: Popcorrin on March 16, 2006, 09:52:48 am

I have a wells gardner 7000 series monitor which doesn't seem to be working at all.  Besides a blown fuse what is usually the cause of a dead monitor. 
I checked the fuse and it's fine.  I looked over the board and replaced a few suspect caps.  The solder joints look fine.  The flyback doesn't seem to be cracked or anything.  The tube looks good and I don't know if this makes any difference but the resistance on the windings was 13 and 3.  Nothing really is standing out to me. 

I know some of you guys have alot of monitor experience and I was looking for a little guidance. 

Thanks

Title: Re: Dead Wells K7000
Post by: Ken Layton on March 16, 2006, 10:19:17 am

Do the full capkit, don't just replace a couple of caps. Check for bad solder joints especially resistors R101 and 89.

Check horizontal output transistor. Check the B+ voltage regulator IC. Check fuse with ohmeter.

Title: Re: Dead Wells K7000
Post by: SirPeale on March 16, 2006, 07:15:36 pm

If you can get ahold of Randy Fromm's flowchart for this monitor, I suggest you do so.

Title: Re: Dead Wells K7000
Post by: Popcorrin on March 24, 2006, 06:56:24 pm

Thanks for the advice.  I think it is the horizontal output transistor.  It is only registering at around 1 ohm.  Just curious where the best place to get a replacement is? 

Thanks

Title: Re: Dead Wells K7000
Post by: SirPeale on March 24, 2006, 07:19:34 pm

You don't diagnose transistors with an ohms reading, you use the diode tool.

Do a Google search (http://72.14.203.104/search?q=cache:XkoyAUGGv74J:slot-tech-ftp.serveftp.com:8080/general%2520electronics/power%2520supplies/power%2520supply%2520repair/psrepair.htm+Randy+Fromm+Diode+check+&hl=en&gl=us&ct=clnk&cd=1) for 'voltage drop diode' or 'junction drop'

Do you get high voltage?  Usually if the HOT goes, IIRC you get a line in the middle of the screen, and nothing else.

If you turn up the screen control, does the screen go white?

Title: Re: Dead Wells K7000
Post by: Ken Layton on March 25, 2006, 01:16:23 am

I use my analog meter to check the horizontal output transistor. To check it correctly you must unsolder it from the board lest you get false readings from the flyback and other low resistance item in the circuit.

If you are measuring 1 ohm of resistance from any of the transistor terminals then it's shorted! You can buy replacements from Bob Roberts. Remember that this transistor requires a mica insulator and silicone grease between it and the aluminum frame.

Title: Re: Dead Wells K7000
Post by: Popcorrin on March 25, 2006, 12:31:29 pm

Thanks Ken.