CurtPalme.com Home Theater Forum

[jaredjaric]

I have installed the DIY splitter and it is potted in red high temp silicone,
The red silicone is rated at 650 degree f, and is a branded automotive RTV silicone gasket maker.
For me high temp and high voltage insulation are totally related.

So far no hissing sound and voltages are stable at 33.8V dc.

Main issue, FOCUs is really bad. As shown in the pics below, contrast is down to 20 to avoid blooming.

Out of focus is on all three crts, had to rule out video amps,
since on a normally working splitter, the focus was tight on these same neck cards.

Pleass help me out guys, what causes the blooming / soft focus ?

[jaredjaric]

out of focus screen shot

[jaredjaric]

screen shot

[Curt Palme]

I'm completely impressed that it works!

If you have blooming, you have bad HV regulation. If it's the same as before you modded the splitter, then I'd suspect the EHT board. If not, then the quad.

Those are the only 3 parts in the entire HV section, the problem is, they all interconnect, with that white wire being the feedback loop from the HV output to the EHT board. But.. there's nothing else outside of those 3 parts that can cause HV problems.

While a scan fail will affect HV, it will simply shut it down, and not cause blooming or other HV problems. Ditto for a bad video card, as there's a connection between one of the RGB cards and the scan fail shutdown line.

[Curt Palme]

I'm completely impressed that it works!

If you have blooming, you have bad HV regulation. If it's the same as before you modded the splitter, then I'd suspect the EHT board. If not, then the quad.

Those are the only 3 parts in the entire HV section, the problem is, they all interconnect, with that white wire being the feedback loop from the HV output to the EHT board. But.. there's nothing else outside of those 3 parts that can cause HV problems.

While a scan fail will affect HV, it will simply shut it down, and not cause blooming or other HV problems. Ditto for a bad video card, as there's a connection between one of the RGB cards and the scan fail shutdown line.

[jaredjaric]

Thanks Curt,

I agree it can not be the EHt and quads, there is nothing outside of the splitter that can cause the soft focus.

I will look into the caps again , might need extra capacitance..????

the resistors i used are rated over the 2 watts that the Barco had , and these are either rated at 5KV or 20kv.

hope to hear more from you guys.

[jaredjaric]

BTW, the 4 caps were in series/parallel and reached measured 3000pf at 60KV ,

might need to go for 6000pf since it connects to the eht feedback circuit that might have inputs to the focus board.

Or the 3000pf capacitance is not an issue ?

[barclay66]

Hi,

I think -before speculating and trying this and that- better get some information on the current status. What I would recommend:

- Get a HV probe and measure the voltage that goes to the tubes (the voltage on the feedback line is only an indirect method)
- Check fuses F100 and F101 on the G2 Diagnostic board
- Verify that the focus board gets all the required supply voltages (+17, +12, -19, -9, FOC_HI, FOC_LO)
- Check all security resistors on the focus board (SR1-SR6, SR30, SR50, SR70)
- Verify that the focus board itself is OK

[Curt Palme]

[Curt Palme]

[jaredjaric]

HI Curt,

I am ruling out the eht and quads,
Since prior to rebuilding the splitters, all systems were clear and good.
i have swapped all the boards and parts, and confirmed that all were running normally.
The remaining good splitter i installed in this cinemax is now in my 909 chassis ,
and is in use every night.
Eventually i will swap back the original barco splitters to be sure that my DIY is or is not the issue.
i have swapped the focus boards , g2 boards and neck cards also.

I will try the splitter swap first and report back.

[dvh99]

were those nos caps still within spec?
they might be 30 years by now.

[jaredjaric]

i will have to assume that these caps are up to specs,
Also, i had just scraped up the globs of silicone and can see that all caps are not bloated.
But i have ordered your recommended Polystyrene caps, i ll build a second splitter with these newer caps.

[ElTopo]

This red thing reminds me of the movie The Blob

[dvh99]

still curious....