CurtPalme.com Home Theater Forum

**Curt Palme** · Posted: Thu Jul 07, 2011 11:52 pm Post subject: Barco blows up quadruplers?

Here's a brand new one for me, I wanna know if any BArco owner has seen this before. Dealing with a planetarium overseas that has a Barco 708 that worked fine until it went into HV shutdown mode. I correctly diagnosed a bad quadrupler, the one in the set had gout (top all swollen out, I see that once in a while).

Sent over a used tested one, customer says that within 5 minutes the top bulged out on it too, despite showing flickering lines on the tubes for a few minutes (AKB line that flickers when no input signal is sensed, so that's normal).

OK, I sent a bad quad, despite testing it for 4-5 hours before sending it. I send another. SAME. DAMN. PROBLEM.

Quadrupler bulges out within about 5 minutes of installing it. Customer had changed the splitter at the same time 'just in case'.

My only guess is that something in the HV/EHT section is causing the quads to blow, but what? I'll send another quad, and I'll get him to buy a new SMPS/HV board, but this is a fault I've never seen before (nor can either one of us afford it. Smile

)

Any guesses?

Following the Barco HV rules, the old quad (7622091) should be able to be used in the new style SMPS/HV (if he has that, I'll get that confirmed). Something mut be getting REALLY hot in the quad for it to bubble like that. What's bugging me is that the BArco HV sections are REALLY well protected, any current overload, and the thing should go into HV shutdown mode...

stefuel · Posted: Fri Jul 08, 2011 4:28 am Post subject:

This will be a really long post

BAD TUBE

**Curt Palme** · Posted: Fri Jul 08, 2011 4:51 am Post subject:

I'm not sure about that, but it's possible. Thing is, a shorted tube would drag down the HV, and put the set into shutdown mode. That's my guess anyways. Ditto if the focus block were shorted.

Tom.W · Joined: 09 Mar 2006 Posts: 6635

Could too much voltage coming out of the EHT feeding the quad cause this type of failure ?

You could do a quick check with an ohmmeter of the tubes and the splitter...

WTS · Joined: 08 Mar 2006 Posts: 1276 Location: Calgary

Just a guess here but without looking futher into and the schematics I would say the EHT osc/freq has drastically changedand I would think it has decreased. Send him a new EHT. SMPS board has very little to do with it as it only supplies a HV DC to the EHT. Unless of course the supply caps are toasted on the SMPS, those are the ones smoothing out the line voltage after the rects which are connected directly to the supply AC line.

Let's not be killing anymore quads as I don't have time to rebuild more of them.

**Curt Palme** · Posted: Fri Jul 08, 2011 2:05 pm Post subject:

Walter, that's pretty much my guess at this point. THe SMPS and EHT section in the 70X series sets is the same board, so that's what I'm sending him. I'll respond to your last email while on the road. Been putting in 18 hour days for the last 2 weeks, and I still didn't get time to answer everyone..

WTS · Joined: 08 Mar 2006 Posts: 1276 Location: Calgary

I didn't relize that the SMPS and the eht were on the same board.

Ahh the joys of running your own business - 18hr days.

No hurry on the response, thanks.