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jaredjaric
Joined: 05 Jun 2007
Posts: 228
Location: Philippines
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 Link Posted: Mon Sep 21, 2020 4:41 pm Post subject: |
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i mean are those RGB posts wired in parallel going to the eht feedback board ?
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mp20748
Joined: 12 Sep 2006
Posts: 5681
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Link Posted: Mon Sep 21, 2020 5:56 pm Post subject: |
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| jaredjaric wrote: | | i mean are those RGB posts wired in parallel going to the eht feedback board ? |
According to the image Barclay posted in a thread previously, there seems to be something on each post. Waht those devices are I have no idea.
Curt may be of help here, and if not maybe Barclay would know what's going on inside that unit, because he had suggested looking at using a Marquee splitter I think.
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dvh99
Joined: 25 Dec 2009
Posts: 2158
Location: nederland
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| Link Posted: Mon Sep 21, 2020 6:11 pm Post subject: |
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barclay suggested using a marquee splitter because they hardly ever fail.
i can attest to this  .
the resistor needed depends on the trimpot value as he explained.
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1 answer always poses multiple questions.
marquee 9500ultra HD10L moome hdmi1.3 v3+ some mods.
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24301
Location: Langley, BC
TV/Projector: All of them!
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| Link Posted: Mon Sep 21, 2020 6:48 pm Post subject: |
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I've thought of that, but that 30 volt tap is the feedback loop to regulate the HV. If that isn't precise, then you can increase the HV uncontrollably to 50Kv+, and snap tube necks as a result. Even in the Barco service manual, they say not to touch the trimpot on the splitters, since the setting is so critical. Proceed at your own risk.
Next month, hopefully sooner than later, I will set up a 909 here, and run through a good portion of my quads and splitters. I'll test each pair for 12 hours, then sell them off for lower than I have before. I have likely 50+ splitters here, and 30+ quads. Almost no EHT boards, but I will post a little trick that I found on those as well to help with the stupid EHT shutdown.
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jaredjaric
Joined: 05 Jun 2007
Posts: 228
Location: Philippines
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| Link Posted: Tue Sep 22, 2020 12:33 pm Post subject: |
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| mp20748 wrote: | | jaredjaric wrote: | | i mean are those RGB posts wired in parallel going to the eht feedback board ? |
According to the image Barclay posted in a thread previously, there seems to be something on each post. Waht those devices are I have no idea.
Curt may be of help here, and if not maybe Barclay would know what's going on inside that unit, because he had suggested looking at using a Marquee splitter I think. |
Those on the posts are resistors at 10kohm each, i am referring to the dotted line, does it mean high voltage?
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mp20748
Joined: 12 Sep 2006
Posts: 5681
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Link Posted: Tue Sep 22, 2020 1:12 pm Post subject: |
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The dotted line in the diagram is a Feedback line that's used to regulate the high voltage as Curt pointed out. That section of the diagram is where the sealed Pot is located. You should see a small and separate maybe shielded wire connected on the splitter that also goes to the chassis. That wire would be your dotted line on the diagram.
That area in the diagram and on the splitter would be what we call a "Critical Safety Component" area. And is also as Curt had pointed out would need to be a precisely set Pot (glue). That Pot would either be used to help regulate the high voltage or be used as a shut down enable for over voltage protect, or both.
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dvh99
Joined: 25 Dec 2009
Posts: 2158
Location: nederland
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| Link Posted: Tue Sep 22, 2020 7:48 pm Post subject: |
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| jaredjaric wrote: | regarding the insides, i have determined the resistors are 6 10k ohms carbon type 3watt ratings and caps at 4 pcs. 6kpf 10kv rating and that is all.
i just don't know what those dotted lines in the diagram means, it shows parallel wiring, which i doubt very much. |
on barclay`s picture it suggests there are only 2 caps present in the splitter.
so you say there are 4 caps?
and if so how are they connected?
perhaps 2 in series with the other 2 also in series and paralelled.
something like this.
____________
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C C
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C C
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^ ^
^=ground
_________________
1 answer always poses multiple questions.
marquee 9500ultra HD10L moome hdmi1.3 v3+ some mods.
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jaredjaric
Joined: 05 Jun 2007
Posts: 228
Location: Philippines
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| Link Posted: Tue Sep 22, 2020 9:47 pm Post subject: |
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| dvh99 wrote: | | jaredjaric wrote: | regarding the insides, i have determined the resistors are 6 10k ohms carbon type 3watt ratings and caps at 4 pcs. 6kpf 10kv rating and that is all.
i just don't know what those dotted lines in the diagram means, it shows parallel wiring, which i doubt very much. |
on barclay`s picture it suggests there are only 2 caps present in the splitter.
so you say there are 4 caps?
and if so how are they connected?
perhaps 2 in series with the other 2 also in series and paralelled.
something like this.
____________
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C C
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C C
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^ ^
^=ground |
the caps are in parallel then series.
so two 6000pf in parallel and two pairs in series.
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jaredjaric
Joined: 05 Jun 2007
Posts: 228
Location: Philippines
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| Link Posted: Wed Sep 23, 2020 2:55 pm Post subject: |
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I just found out what those dotted lines stand for.
It is the barco mega ohm resistor going back to the eht diagnostic circuit.
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24301
Location: Langley, BC
TV/Projector: All of them!
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| Link Posted: Wed Sep 23, 2020 3:41 pm Post subject: |
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| jaredjaric wrote: | I just found out what those dotted lines stand for.
It is the barco mega ohm resistor going back to the eht diagnostic circuit. |
It's actually that shielded white Teflon wire that is super hard to strip. I made the mistake more than once of forgetting to connect that, or the hot wire came loose after soldering, and I didn't catch it. That will also send the EHT to well over 50Kv, and arcing happens everywhere. I was lucky not to blow the neck of the tubes off!
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jaredjaric
Joined: 05 Jun 2007
Posts: 228
Location: Philippines
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| Link Posted: Thu Sep 24, 2020 5:29 pm Post subject: |
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| barclay66 wrote: | In theory, it would be possible to replace the Barco splitter with a splitter from a Marquee (which rarely fail). What would have to be compensated is the missing High Voltage feedback line. Inside the Barco splitter there is a resistor connected to the HV-Line which -together with the pot on the small PCB- works as a voltage divider (something like a 1000:1 ratio). If this resistor could be placed at the input of the Marquee splitter, it just would do the same as in the Barco.
Please refer to the pictures below. The required resistor would have to be a HV-type or a chain of smaller resistors. Its value would have to measured (difficult) or to be calculated from the pot value.
If we call the HV-Resistor R1 and the pot R2 then for a 1000:1 ratio (Vin = 1000 * Vout) the formula is as follows:
R1 = R2 * ((Vin-Vout)/Vout)
So for 35KV as Vin, 35V as Vout and a pot value of 100K ohms (=100000 ohms) we would get:
R1 = 100000 * ((35000-35)/35) = 99900000 ohms
So, this would be a 99,9 megaohms resistor |
I get it,
Inside the barco splitter is a 150 Mohm resistor.
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jaredjaric
Joined: 05 Jun 2007
Posts: 228
Location: Philippines
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| Link Posted: Wed Oct 14, 2020 5:14 pm Post subject: splitter rebuild |
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after stripping and scraping bad splitters,
I am rebuilding or making a new one, all resistors are metal film 5kv rated, and caps are the eros 30kV rated 3000pf .
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I have an old school tech guy doing it for me to make sure all is right.
Hoping this goes well
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dvh99
Joined: 25 Dec 2009
Posts: 2158
Location: nederland
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dvh99
Joined: 25 Dec 2009
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dvh99
Joined: 25 Dec 2009
Posts: 2158
Location: nederland
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| Link Posted: Thu Oct 15, 2020 4:46 am Post subject: |
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1 more thing to consider is shelf life.
i have no clue how long these caps stay well but the first link and the equivalent of the ones in the barco splitter are new old stock and perhaps 25 years of age.
to be on the safe side i`d opt for the second link i provided but maybe curt or barclay ormike chime in and have a more professional verdict.
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1 answer always poses multiple questions.
marquee 9500ultra HD10L moome hdmi1.3 v3+ some mods.
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24301
Location: Langley, BC
TV/Projector: All of them!
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| Link Posted: Thu Oct 15, 2020 1:49 pm Post subject: |
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From what I've seen and read online, finding the HV parts isn't nearly as big of a problem as sealing the quads and splitters so that they do not arc internally. Following with interest.
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barclay66
Joined: 27 Jun 2011
Posts: 1291
Location: Germany
TV/Projector: Marquee 9500 Ultra
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| Link Posted: Thu Oct 15, 2020 7:25 pm Post subject: |
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In any case I always would use new parts when building something. Especially when it comes to high voltages and/or currents. First of all, the plastic used for capacitors could develop cracks over time and resistors age too. Secondly, newer parts tend to be smaller and could give You an advantage as You could leave more space between them.
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jaredjaric
Joined: 05 Jun 2007
Posts: 228
Location: Philippines
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| Link Posted: Thu Oct 15, 2020 11:14 pm Post subject: |
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I am using these NOS polyester films as i have a bunch of them,
I will try those polystyrene later, tech guy says they maintain capacitance better at HV , but more prone to heat stress.
but i really prefer the higher temp ratings of polyester films.
it has better insulation both from voltages and heat.
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dvh99
Joined: 25 Dec 2009
Posts: 2158
Location: nederland
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| Link Posted: Fri Oct 16, 2020 8:03 am Post subject: |
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not cheap but sufficient electrical insulation i guess.
you might want to contact barco and ask which compound they used or in any case which properties the compounds used have as the one from the link above is plus 100 euro.
https://nl.farnell.com/mg-chemicals/8820-2-55l/potting-compound-pur-can-2-55l/dp/3018431?st=high%20voltage%20potting%20compound
Cured Properties
Electrical Properties Method Value
Breakdown voltage @3.175 mm [1/8"] Reference fit a) 47 300 V [47.3 kV]
Dielectric strength @3.175 mm [1/8"] Reference fit a) 378 V/mil [14.9 kV/mm]
Volume resistivity ASTM D 257 1.4 x 1013 Ω·cm
Volume conductivity ASTM D 257 7.0 x 10-14 S/cm
Dielectric dissipation, D @1 MHz ASTM D 150-11 TBD
Dielectric constant, k´ @1 MHz ASTM D 150-11 TBD
Thermal Properties Method Value
Glass transition temperature (Tg) ASTM E 831 44 °C [111 °F]
CTE b) prior Tg
after Tg
ASTM E 831
ASTM E 831
94 ppm/°C [201 ppm/°F]
195 ppm/°C [382 ppm/°F]
Thermal conductivity @25 °C [77 °F] ASTM E 1461 92 0.27 W/(m·K)
Thermal diffusivity @25 °C [77 °F] ASTM E 1461 92 0.15 mm2/s
Specific heat capacity @25 °C [77 °F] ASTM E 1269 01 1.44 J/(g·K)
i am also very curious how this works out.
you might want to use some sort of vacuum chamber to get most of the airbubbles trapped inside out.
_________________
1 answer always poses multiple questions.
marquee 9500ultra HD10L moome hdmi1.3 v3+ some mods.
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gjaky
Joined: 05 Jun 2010
Posts: 2790
Location: Budapest, Hungary
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| Link Posted: Fri Oct 16, 2020 11:57 am Post subject: |
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| dvh99 wrote: |
you might want to use some sort of vacuum chamber to get most of the airbubbles trapped inside out. |
I think this is the key. I mean, mostly anything you can use will have sufficient dielectric strength. On the long run the stability is question, whether it develops micro cracks or how it absorbs water, but datasheets don't tell much in this regard.
Also you have to be careful with the vacuum too, if the vacuum level is too good it may prevent the compound to cure.
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projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB, VIM-DB
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