CurtPalme.com Home Theater Forum

nidi · Joined: 17 Aug 2008 Posts: 305 Location: Switzerland

Hello guys,

just found out that my Marquee nuked another HVPS.

made a mistake in pushing the Power Button twice, switchd the projector off then on and off again

did not power up the next day.

found out today that the HVPS is nuked again.

3rd in one year !

will try to put an a 34kV HVPS , due to better protection.

anyone know how to modify a 'normal' HVPS to have better protection ?

Thanks

Michael

nidi · Joined: 17 Aug 2008 Posts: 305 Location: Switzerland

Guys,

can a G2 short blow the fuse?

how does the protection circuit work on both the 33. and 34 kV PS?

what has to happen for it to be triggered?

if I would use a 34kV PS , would there be any differences in sharpness or any other
problems driving the tubes?

as Steve told me, the 34kV PS has better protection.

Thanks

Michael

HK-Steve · Posted: Mon Jan 09, 2012 3:39 pm Post subject:

Michael,
Think that it was Mike who said it had better protection.

Not sure if the 900volts less to the tube, would effect anything.
34Kv instead of 34.9Kv.

Appreciate your comments and help.

Cheers

barclay66 · Posted: Mon Jan 09, 2012 4:00 pm Post subject:

HK-Steve · Posted: Mon Jan 09, 2012 4:13 pm Post subject:

Agree, but if that is the only tradeoff, then not a big deal.

The Tubes are LUG, do the LUG tubes draw more power than a standard tube?

Cheers

barclay66 · Posted: Mon Jan 09, 2012 4:21 pm Post subject:

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

The 9 inch tubes will not focus as well, been there dine that. you need a 34.9kv HVPS for 9 inch tubes to get the best performance.

I spent weeks trying to fix a bad focus in a 9500 i have. For some reason i swapped in the 34kv unit. I think i was comparing a few 34.9kv supplies I had to see internal differences. I must have just garbed the one 34kv supply i had and put it back in the 9500LC.

Then I looked at the front sticker onthe HVPS and saw the 34kv. Put the 34.5 in and much better focus.

Athanasios

nidi · Joined: 17 Aug 2008 Posts: 305 Location: Switzerland

so then,

how can a better protection circuit be put into a 34.9 kV supply?

I do not want a dimmer picture.

Thanks

Michael

HK-Steve · Posted: Mon Jan 09, 2012 4:43 pm Post subject:

Too much tradeoff, Michael likes his brightness,
sharper is what we want, that is why the LUG's are installed.

Cheers

**Curt Palme** · Posted: Mon Jan 09, 2012 5:18 pm Post subject:

Steve, please explain about the 34Kv vs the 34.9Kv circuits. Supposedly the later the supply, the better built they were, but I've had failures in the potted section of all versions of the supplies, even the latest Ultra HVPS. I don't see much difference, although given a choice, I'd take as late of a supply as possible.

I've got no documentation on why the 8000 protection would be better than the later supplies.

HK-Steve · Posted: Tue Jan 10, 2012 6:41 pm Post subject:

Curt, I am not sure I can explain the differences,
But, the 34Kv looks to have a more robust Mosfet stage, which Mike said earlier.

Here are a couple of pics, that show the difference.

Chers
Steve

34Kv

Revision B 34.9Kv

HK-Steve · Posted: Tue Jan 10, 2012 7:00 pm Post subject:

OK, Just pulled all my other HVPS's off the shelf, and found something interesting.

The photo above of the 34.9Kv HVPS is a revision B series.

Below is a Revision A
Plus a row of broken HVPS's from Michael and myself, the bottom is the 34Kv working unit.

Cheers

Revision A 34.9Kv

A Line of HVPS's,
At the top to the bottom,
Rev. B8
Rev. B1
Rev. A7
Rev. A1
Bottom is 34Kv Rev. C4

HK-Steve · Posted: Tue Jan 10, 2012 7:19 pm Post subject:

So at this stage, all of Michaels HVPS have been Revision B versions.

A B1, a B2, and a B8,
Think this is the issue?
Are they more fragile than the earlier series.

Going to see if I have a working Revision A to try.

Appreciate any comments.
Cheers

barclay66 · Posted: Tue Jan 10, 2012 7:20 pm Post subject:

Hi,

It seems to me, that where You can see only two MOSFETs mounted to the heatsink those are newer ones with integrated antiparallel diode. In the older HVPS You can see those mounted separately. I could imagine that external diodes are able to withstand more stress than those integrated ones. Interestingly even on newer Rev. boards they could be added as there's the space and the PCB traces have been left in.

What I've seen too is that on some daughter boards within the HVPS all ICs were socketed. If over the years those sockets developed problems this of course could interfere with HV regulation and therefore could damage the power section...

Regards,
barclay66

HK-Steve · Posted: Tue Jan 10, 2012 7:27 pm Post subject:

Is it possible to adjust the 34Kv to 34.9Kv, with the right test gear of course !!!!!!!!

There are 3 trim pots on the HVPS, which does what?
or is it in the potted section that holds the secret of the output voltage???

Cheers

HK-Steve · Posted: Tue Jan 10, 2012 7:29 pm Post subject:

Saving cost by not installing them??

Cheers

HK-Steve · Posted: Tue Jan 10, 2012 7:32 pm Post subject:

Also the Revision B series, have a sunken lid on the potted section,
Revision A series have a higher lid on the top of the potted section.

Interesting that all of these HVPS, none have any faulty potted sections, I think,
No smoke, or breakdown of the potted section.

Cheers

HK-Steve · Posted: Tue Jan 10, 2012 7:43 pm Post subject:

barclay66,
Yes I noticed this also,
BUT, it seems more like good luck, than management if the sockets are removed, ie, no pattern.

34Kv, Rev. C4, sockets
34.9Kv Rev.A1, NO sockets

34.9Kv Rev.A7, sockets
34.9Kv Rev.A7 NO sockets

34.9Kv Rev.B series, all NO sockets

Cheers

barclay66 · Posted: Tue Jan 10, 2012 8:07 pm Post subject:

Hi,

barclay66 · Posted: Tue Jan 10, 2012 8:13 pm Post subject: