Anyone intrested how far we can push a 800. Maybe not worth the effort or just a fun project.

Greg

801 rgb amps, switcher and driver would be easiest 60->75Mhz upgrade.

Do you know how to get rid off that "chassis noise" that 500/800/1200 have?

I mean those vertically moving thin lines that can be seen near screen, I have seen that in every 500/800/1200 some level. But not in 801s/808...

Does noise have something to do with onesided circuit board in old smps and bare transformers?

I'm refurbishing my BG1200 and like to get rid of that noise.

Lets start discussing the upgrades. I have done many 1200 units.

WE can start at the convergance tray caps the 1200 has a small daughter board inside the chasis that holds the filter caps on it.

You mean that small four caps board between mobo and convergence board? I try to remove it few days a go to recap, but it seem to be stuck. I think I have to remove tubes and that aluminium plate to get it out. Maybe I leave it until I get R/G C-elements, so I can make modifications at same time.

What kind modifications daughter board need or is just recapping enough?

This far I have recapped smps, convergence, mobo (I make it without removing) and etc.
I have used Sanyo MX-AX caps in filters/smps...

I think they should be fine. I use low esr nichon.

OK lets move onto what you need to do to improve convergance stablility and noise on the 1200.

The 1200 has all the same video boards the 1208 has so what you need to do is up the power rail caps on all the video boards. Including the neck boards.

I can provide a schematic if you need it. When recapping the power supply it does not hurt to move up on some of the UF amounts keep the voltage the same or a higher voltage.

In the neck cards I use a higher voltage lower esr on the Brightness circurts I can show you where to improve the responce.

Greg





BTW

When doing C-elements make sure you take the tubes out of the unit. I had a person who left them in and got coolant on the boards. It shorted everthing.

Also when doing the C-elements wash the chamber well and polish the glass of the CRT well.

This glass can get foggy and cause a unfocused picture. Use new coolant!

GREG

I have 1208 schematics so I can find those power rail caps from those separated power sections.

Is about +50% bigger uF caps ok for those power rails?

That would be nice, because I'm not following. Is there needed some extra cap or something?

Thanks!

Yes you can replace the power rails on each board with 2-3X the value also use a poly type in parellel to get rid of high frequency noise too. 1uf is ok or .47 poly.

But to make it realy good you need to add filters to each amp stage RGB and the final output necks.

Most noise is created from the input secton and them maginifyed as it gets to the necks.

GREG

Funny how i just came across this topic, i got a pristine BG800 with like new everything. Going to go all out in every regard, i dont care how long it takes me to be honest.

So far i have done the following:

Recapped all bipolar caps to Muse-Es 50v 33uf (Shiny green), recapped Rgb amps to panasonic FC. Replaced many stock lytics to FC. Replaced silver mica with much bigger and better kind.
Bypassed power input with Wima Mkp10; seems i might have issues upgrading the LVPS caps since mounting is troublesome (caps got positive center(?) wich means new big caps will be offset from the holes).
Rewired yellow leads from imput switcher card to very high quality Gigabit dual shielded massive copper cable (just barely fits in stock cable clips).
Ground shielded every big IC on all cards with thick copper foil. Even the convergence tray.

To do list:

Replace every last cap on every board to FC or FM. old Mkt to Mkp-10 / Mkp1837 (high grade bypass) all small cheap mica to bigger better type. Since the set is getting old im going to do it.
HD144/5 clear lenses with adapter (got nice tinted glycol already)
Might change to one piece aluminium Rgb amplifiers, didnt know they were exchangable before i did the sheet metal ones.
Rewire most cheap yellow wires to Lanmark-6 Utp-6 (specially those carrying Rgb)
Sandwich shield many electromagnetism prone areas, mesh and foil shield all HV leads.
Change Bnc receptables to very high grade gold plated type, rewire coax leads that go from them into mainboard with larger trishield type.
Change out all Motorola 2n2905 and PH Bsx20 to higher BW (if possible)
extreme silver contact enhancer on all tube pins and connectors
Sand blast and copper dip the entire steel chassis (got the gear for it)
Sand down, plastic prime and paint the entire case piano black.
Change steel vent mesh to copper mesh with ground

Futile and stupid some might say but i dont care to be honest, it like the extra work instead of just going out to buy a 9" LC Em focus set.