CurtPalme.com Home Theater Forum

[cosaw]

Hi all,

Years since I've been on here. Best wishes to you all!

Trying to resurrect a Barco 808 Graphics here in the UK. The quadrupler was dead. I have one from a data 500 that brought it mostly back to life some years ago but it's not been started for years due to health.

My concern on the Quad is that the replacement has different exit points for the red high voltage lines (out the side instead of out the top. They mean it can't bolt to the chassi like the original would. It's floor mount so it's not a problem if it can just sit there but does it need to couple to the chassi for heat sinking or for continuity between the steel part on the quad and the chassi? Not wanting to cause premature failure.

Also. Sorry if it's been covered many times before. It's not been powered up in years. Is their inrush protection for the capacitors? Being an SMPS I gather bringing it up on a Variac would not be a good idea. Also I don't know if a dim bulb tester is advised either. I could just go for it and hope for the best. Worst comes to worst I could desolder the big caps and put them on DC to reform them but could be a lot of work.

All suggestions welcome.

Many thanks in advance,

[Hulio]

Hello Simon,

Firstly, the biggest concern regarding the quad is not the physical mounting method, but compatibility.
Not all combinations of EHT/quad/splitter/frame will work. If everything in your BG808 is still original, the EHT, splitter and frame are all "new style".
The quad from a BD500 (supposedly R761743 or R7622091) is "old style". According to Barco, this combination will give high voltage oscillation.
About mounting: there is no need for the quad to be flush mounted to the chassis, the opposite is true. Isolated from metal is best. Folks are using thick plastic or rubber washers to accommodate the mounting of quads with different wire layout.

I don't think you can do something about the electrolytic caps inrush protection. There is a tiny delay at start up, but for the rest not much you can do about it. Maybe starting in standby first can help....

[Hulio]

Oh, forgot to add the link to Barco's service bulletin about HV components compatibility.

http://www.curtpalme.com/docs/BarcoServiceBulletin_R762716_New_EHT.pdf

[virusc]

Barco 500 data is a early 800data really. I do not think it will be compatible. I have swapped 500/800 and some 801 parts around as they are all ES projectors that are similar in function. A 808 is a EM unit and is much newer.

[cosaw]

Hi Guys! Many thanks for the replies and advice.

To be honest I really need to do my homework on this. Spent most of the weekend on it searching through what I've got in terms of parts and the projector. Part of me wants this to be the end of the road (after all these years) but then there is the part of me that doesn't like to leave things unsolved.

Real big thank you Hulio! You pointed me just where I needed it seems.

So the projector is a bit of a Frankenstein's Monster. It seems it was originally a Graphics 808s (which I think has the Sony tubes) but it seems the Panasonic tubes were put in it and a change in what I think is the focus board. I think there were other mods supposedly to bring it to Cine spec - or that's the story I was told. The chap who put it together I think was one of the main guys in the UK at the time but I believe he is no longer with us sadly. I bought the machine the best part of a decade ago now, thinking it would be just a case of swapping the Quad out.

May have been barking up the wrong tree then in thinking that the old style Quad was gonna work - I thought I'd verified this some years ago but maybe that explains some of the issues I was still getting. It was strange - seemed tubes displayed for ceiling (at least in part) but for floor I think I got text on green and that was it. I blamed the scan inversion switches on one hand but on the other I thought there should be absolutely nothing wrong with them.

So Currently I have:
Splitter with absolutely no model number on (unless it's underneath).
Quad R761743 (from the Data 500)
New frame R7625021 (according to motherboard - back sticker doesn't show this but shows: R9000903)
New EHT R762716

Hulio, seems you were spot on and the table in the document you posted points to oscillations for that arrangement.
I obviously have a splitter that worked at some point (even if I can't see the number). But from the table it looks like the results are the same regardless of splitter model anyway.

So in the spares I have 4 Old Style EHTs. 2 x 76142.5 and 2 x 7617427. What the difference is and why one has a decimal point I don't know but you would think 7617427 supersedes 76142.5

If you can help me understand further from that document. Does it suggest that if I use old quad and old splitter it's just a case of resoldering a jumper on the underside of the motherboard to get this working? Or have I misunderstood or does the document gloss over what would happen in that arrangement. Need to check schematics but can the jumper be made on the old EHT board rather than the mainboard?

Don't really want to strip it down to nothing just to get to the bottom of the mainboard and then have it not work anyway because I misunderstood something.

Thanks, in advance, for your patience, I'm not really any good at being concise.

[Curt Palme]

Old quads will work in later Barcos. New quads (763XXX) part numbers will blow up the output transistor on the EHT board due to oscillations.

If the HV leads come out the side, use a nut or washers and a longer M4(?) bolt to hold the quad away from the chassis, so you can route the HV leads up and out of the side of the chassis.

That's all there is to it.

Splitters are interchangeable throughout the Barco line (with the exception of the old 400 and 600 series projectors)

[Curt Palme]

Old quads will work in later Barcos. New quads (763XXX) part numbers will blow up the output transistor on the EHT board due to oscillations.

If the HV leads come out the side, use a nut or washers and a longer M4(?) bolt to hold the quad away from the chassis, so you can route the HV leads up and out of the side of the chassis.

That's all there is to it.

Splitters are interchangeable throughout the Barco line (with the exception of the old 400 and 600 series projectors)

[Hulio]

Hi Simon,

Was the Barco guy from UK by chance James Soanes from crtprojectors.co.uk ? I knew him...
Indeed, swapping the Sony tubes with Panasonic, involves a mod on the focus board. Only Sony tubes use the mini-splitter from the focus board, Panasonic not.
About scan inversion: keep in mind that text display is always on green only, so it might be nothing wrong with the switches. Only from software version 7.61 on, the OSD can be also magenta, yellow or red.
Ok, now back to the high tension stuff: the bottom line is, you can never mix old style quads with new style EHT's or vice versa. They have to be as a set (both old style or both new style). Don't worry about the splitter, they are all interchangeable.
So you have two options:
1. Buy a new style quad (here a link https://www.ebay.com/itm/277369876748?itmmeta=01KGZCECVMZPQ1G5QN9HE2Z48H&hash=item409488710c)
2. Use a old style set of quad/EHT and modify the jumper on mainboard to accept it.
For this mod, there is not really necessarily to demolish the mainboard, but you can make some solder work at the EHT.
As you could see from that service bulletin, on the new frame, the arrival of drain (DHV) happens on pins 29 and 30 of the connector.
On the old frame, that happens on pins 27 and 28, and those traces on EHT you need to solder together.
I have somwhere a picture of this mod, but i reached my max. upload limit here. I can send you a mail, if you wish...

Cheers

[cosaw]

Thanks Curt and Hulio for the further responses - much appreciated!

Hulio it seems you are completely correct if we go by the book - as it were. But it seems, that Curt is saying that there are exceptions to those rules.

So I will go with what Curt says as an easy start point. I seem to remember it's what he recommended previously. Sorry if we're treading old ground. When I get round to putting the machine back together I'm just going to stick the old Quad (R761743) back in to begin with. This is where I was at last time (some years ago) and had the set partially working. I'm willing to take a risk because at this point in my CRT journey my health is the main barrier and if it blew up it would be one more thing I could get rid of! Albeit with a lot of sadness. Alternatively if the set was working it's far more desirable for somebody to collect even if I only got £1 for it on Ebay. It would be worth it to get the set shifted. I'm just not well enough anymore.

Hulio I hear what you are saying with the scan switches but I seem to remember that there was something more to it than that. Seem to remember Blue and Red were just dead. Anyway I won't comment on it further, to save any confusion, until I investigate again. Afterall I'm going off memory and it was certainly over 5 years ago. As far as using both old Quad and old EHT I'd still like it as an option. It would be great if you could mail me Hulio with any info you've got. I've repaired plenty of stereo amps over the years so I know how to solder and read schematics. That's why I was thinking that the mod may be able to be achieved on the EHT board. However, I didn't give it much proper thought and until I did I wouldn't take it as obvious. Wouldn't be looking to buy any more projector parts - I need to draw a line in the sand at some point.

As to the chap deceased. I probably shouldn't have commented - not remembering the whole story. I do remember that he wasn't old and by all accounts was a really nice guy. Sorry if I caused any distress to anyone.

[cosaw]

Quick follow-up question. Been busy reassembling this unit. The Quad I've got doesn't have the clear heat shrink tubing on the thick red wire. Is this a problem? I presume it's extra insulation because of the high voltage. I could cut the tube off the dead quad and zip-tie it to the new quad but I don't think that's gonna be much good if it's insulative. Alternatively I can get some new clear shrink and put it on but don't know if it has to be specially rated?

[Curt Palme]

You should be fine. Some had it, some didn't.

[Curt Palme]

You should be fine. Some had it, some didn't.

[cosaw]

That's great Curt! Many thanks for the rapid response!

[alb_qwerti]

Hi,

I used the old style quads (R761743 from BG800 or R7622091 from early BG808) on the newer units without oscillations.

Regards,
Alberto