CurtPalme.com Home Theater Forum

[Joust]

The picture came from AVS. I'll replace them with those from Athanasios with his permission.
nice work.

[PaulB]

My apologies for hi-jacking the thread but it did seem very relevent to the situation and as it turned out, it has certainly has been very useful to myself and hopefully others who have or who are about to delve into the HVPS.

An updated guide would be much appreciated Joust - if I can contribute in any way, please let me know.

Thanks for the input Athanasios, excellent stuff!

Paul

[Nashou66]

Sure I'd be Honored .

Athansios

[PaulB]

[JustGreg]

Is Spellman still making the HVPS or did VDC buy the rights to make them themselves or...???

Also, is there an English translation page for Jeahong's (??) site?

[Nashou66]

here are his post from the AVS archives.

http://archive.avsforum.com/avs-vb/showthread.php?s=c9d33be1287f937dc6c027271a09e752&threadid=416624&perpage=20&pagenumber=1

And this one:

http://archive.avsforum.com/avs-vb/showthread.php?s=&threadid=401345

Athanasios

PS also check out all the other links from those posts lots and lots of interesting stuff even links to Mikes original marquee posts.

[cmjohnson]

Update: I resoldered all connections and tried it out again.

Got stunk out immediately.


Took the HVPS back out and did a more careful inspection of the suspect resistors, which I verified by the touch test to indeed be hot
enough to burn a fingertip.

The bottom resistor was noted to be BURNED IN HALF. And the upper resistor is cracking and the red color band on it that was clearly
red last night is now turning brown from heat.


I tend to think that the lower resistor failed due to age and use and that greater load on the remaining resistor caused it to fail very rapidly. I think that there's nothing else wrong with the HVPS.

Incidentally, these resistors are 200 ohms, not 220. When I first looked at them, the band colors on the upper resistor were quite
clearly red, black, brown, gold. 200 ohms, 5 percent.

I will be replacing those and all similar resistors immediately, with properly rated replacements. I'm not very worried about the caps,
though, as they're not limited life electrolytics.

Man, those burned resistors STINK! The HVPS is sitting on a table behind me and I can smell it without any problem at all.

So what do you figure is the max voltage pulse that goes through those stacked resistors?



Hey, this is actually kind of funny. Just for the heck of it, about a week ago I stuck an AmPro badge on the power supply
bay cover on my 9500.


And the very next time I went to watch a movie, it did exactly what AmPros are known for: The Spellman power supply
crapped out!

What are the odds?


About even money....


Talk about a JINX.


Anyone want a bunch of free, NOS flexible clear rubber AmPro badges? Free?


CJ



CJ

[Fujifrontier]

i'll put one on my sony and see what happens

[CRT_Ben]

[Nashou66]

Chris

[AnalogRocks]

I think CM, you shouldn't even mention Amproxx in the same room as a spellman.

[AnalogRocks]

I think CM, you shouldn't even mention Amproxx in the same room as a spellman.

[stefuel]

Quick, everyone with a working AmPro HVPS put a Electrohome sticker on it.
That's my secret and how I'm able to wear out tubes in a 4600HD. All you need to do is convince it that it's a Marquee and it will behave like one

[cmjohnson]

Update II:

I elected to do a trial fix by replacing both cracked, burned 200 ohm 2 watt carbon composition resistors with two
ceramic body FIVE watt 200 ohm resistors, and it worked like a champ. Watched a movie tonight and not only did I
notice NO funny smells, but something has definitely improved.

Lately I was getting some not-too-faint streaking of on-screen menus. That's GONE now.

Imagine that!

But think about it...the HVPS DOES do just one job, which is to provide 34.9 KV to the anodes of the CRTs,
but think about it dynamically and you'll realize that the HVPS has to be absolutely stable regardless of whether
current demand is at maximum (all three tubes at full white) or current demand is at minimum (all three tubes
in cutoff) and the rate of those demand changes is the full video bandwidth of the signal. If you had alternating
full black/full white pixels displayed in a given scan line, then the power supply has to be stable enough to
provide the full current load without sagging when the electron beam is at full power.

Those resistors weren't doing their job as they slowly roasted. Though I'm not familiar with the circuit they're
in, it CLEARLY has an effect on the image.

So from now on, consider streaking to be a POSSIBLE indicator of a problem in the HVPS. Start by carefully checking
out those two big stacked resistors.


CJ

[Nashou66]

CJ your right. and those two resistors i don't think are part of the G2 circiut. wait till you change out the rest of those whimpy carbon composite resistors. with regards to your comment of full black/full whit pixels on a same scan line, its like a good amp in audio having to be stable and powerful enough to control the voice coil buy pushing and STOPING it on a dime. That is what gives you a tight sounding bass, as a more stable power supply in video will give you a more stable and cleaner picture. the streaking will be minimized.

Now go and change the carbon comp resistors on your neck boards and watch you focus tighten up some too!

Athanasios

[1031]

[Nashou66]

[1031]

[Nashou66]

Did the oscons make a difference?

Athanasios

[1031]

Not much, just little cleaner picture.

[Nashou66]

Cj have you got a chance to change out the rest of the resistors? just curious about any image inprovement and thoughts.

Athansios