[TechAssist] Re: Mitsubishi VS 5006 repeat vert fail???

  • From: Ralph Dorsey <Merlin-Wizard@xxxxxxxxxxxxxxxx>
  • To: techassist@xxxxxxxxxxxxx
  • Date: Thu, 20 Sep 2001 20:25:36 -0500

in all mitz's, change the cap's in the main regulation circuit first, then 
change the chip (vert)  and the caps immediately around the vert chip,,also 
check for the yoke connections that might be loose at the yokes themselves

Damon wrote:

> Hello everybody,
>
> I have a VS 5006 that had a dead vertical Ic about 2 weeks ago. I had 
> replaced the LA 7838 vertical output, along with c4000 and c4006 which are 
> the 28 volt power supply filtering caps, the 10 volt zener diode on pin 1 of 
> the ic, and also had a dead SMPS output ic which isn't even associated with 
> the vertical circuit. When I installed the new vertical ic, it didn't even 
> work, fortunately I had another one, installed it and it ran fine for 2 
> weeks. Now I'm back on the job again with a dead vert ic and wondering if I 
> ran into a bad batch of LA7838's or if I'm missing something on this repair.
>
> Here's what I'm seeing: 10 volts is present on Pin 1, sync is present on pin 
> 2, my 28 volt supply is running at 14 volts (this uses a 28 v Ihvt supply) 
> and the diode and resistor on the 28 v supply measure good. Looks like the 
> vert output is loading down the 28v supply, but nothing is smoked. the vert 
> yokes each measure 2 ohms for a total of 6 ohms, so I don't think I should be 
> looking at that..... Any body had any problems like this? The vert pump up 
> diode measures ok too.
>
> Thanks to anybody who has seen this problem and can resolve this.
>
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