BVP-4 schematics, service manual, or ICs?

[KentIverson]

Hello all,

I own a beige BVP-4. I’ve always wondered what the chips are as ALL of them have been brutally sanded down , scarily so in the cases of a couple of the 16-pin units.

I did a search here and didn’t see this question posed, thus, new thread. Does anyone have the service docs or schemes to this thing?

[BarryTheCrab]

I’m very interested in any answers as I have BVP+.
Although it runs very nicely it has a vertical line on the left side, that can be difficult to mask, depending on the capture card.
I’d love to get some paper on it.

[RobustReviews]

If this processes everything in the analogue domain it should be fairly easy to reverse engineer it, probably why the chips were sanded down otherwise it'd be an A Level electronics project to copy. If it's all analogue the parts were probably very common and available for a few currency units from your nearest electronics hobbyist shop.

Cascaded amplifiers and some filters I guess, what they are is anybody's guess but if you start probing you could probably take some guesses. My Google-foo isn't good enough to find anything relevant.

[lordsmurf]

Elite Video was somewhat cutting edge, in terms of being willing to allow such extreme correction.

Elite was mostly a one-hit-wonder (BVP4/BVP4+), then gone. There's not a lot of documentation out there. I do actually have all manuals, plus some other paperwork that came with the unit when new. Nothing overly useful, however.

The units had intrinsic issues, such as edge luma ghosting, NTSC only, overscan line creep, etc. I often wonder if some of that could be better addressed with undocumented tweaks.

Worst of all, lousy documentation, lots of undocumented features (board pots, etc).

I need to see if mine is sanded as well. Probably. That was just how video gear was done back in the late 90s and early 00s. Too much industrial espionage and reverse engineering in those days. Still is, but it's largely handled in other ways, not by sanding chips.

[KentIverson]

Thanks, all.

I do assume that the 8-pin units are all dual op-amps and that the 16-pins units are likely quads. I always (like everyone, I guess) prefer official service docs as time is so limited.

Fortunately, my unit is working well except that the HBF is often brutal.

[dpalomaki]

Just opened my BVP4. As to active components, I note the IC are color coded as follows:

8 "green" 8-pin DIP
7 "red" 8-pin DIP
1 "white" 8-pin DIP
1 "blue" 8-pin DIP
1 "white" 8-pin DIP

2 "green" 16-pin DIP
1 "red" 16-pin DIP
1-"gold" 16-pin DIP

There are 3 TO-220 case semiconductor devices
LT1089CT switch
TIP29C NPN power transistor
TIP30C PNP power transistor

1 MPF102 N-channel VHF amplifier JFET in TO92 case
1 2N4401A NPN general purpose transistor in TO92 case

I has 3 internal adjustment pots (1 is a 10-turn allowing precise adjustments)
It has two sets of jumper pins

The two internal boards are single layer with widely spaced traces on both side so making a copy of it would be relatively easy.

The boards are labeled COPYRIGHT 1994 VERSACHROME.

The front panel POTs are all branded MOUSER

http://www.digitalfaq.com/forum/vcr-...-bvp-bvp4.html is an old thread on the BVP-4

[RobustReviews]

Quote:

Originally Posted by dpalomaki

Just opened my BVP4. As to active components, I note the IC are color coded as follows:

8 "green" 8-pin DIP
7 "red" 8-pin DIP
1 "white" 8-pin DIP
1 "blue" 8-pin DIP
1 "white" 8-pin DIP

2 "green" 16-pin DIP
1 "red" 16-pin DIP
1-"gold" 16-pin DIP

There are 3 TO-220 case semiconductor devices
LT1089CT switch
TIP29C NPN power transistor
TIP30C PNP power transistor

1 MPF102 N-channel VHF amplifier JFET in TO92 case
1 2N4401A NPN general purpose transistor in TO92 case

I has 3 internal adjustment pots (1 is a 10-turn allowing precise adjustments)
It has two sets of jumper pins

The two internal boards are single layer with widely spaced traces on both side so making a copy of it would be relatively easy.

The boards are labeled COPYRIGHT 1994 VERSACHROME.

The front panel POTs are all branded MOUSER

http://www.digitalfaq.com/forum/vcr-...-bvp-bvp4.html is an old thread on the BVP-4

Interesting, this would be pretty easy to draw and recreate, I expect most of those ICs are simply Op-amps, possibly an old 8pin DIP active-filter IC or two (any crystals in there?) and... well... probably not a lot else. All project level electronics enthusiasts stuff in the first instance, although getting a reliable and noise immune design would be left to a proper EE.

Could even be using discreet active op-amp filtering, so a lot of those amps may be doing that duty.

Also, but the strict best practice you 'should' use a plastic pot-adjuster rather than a metal screwdriver, it's not especially critical in something done 'by eye' but in stricter environments, conductive screwdrivers should not be used to adjust potentiometers... in theory (!)... Sorta.

[lordsmurf]

I don't know that I'd seek to recreate the BVP4. Improve on in, yes. Just recreate, no. Too many issues.

I'd be far more interested in recreating the SignVideo proc amp (YUV), adding with Sima proc amps (RGB), and then taking a few nods from how Elite gave harsher/wilder abilities. The resolution boost on the BVP5 was crap, the detailer from SignVideo does it way better.

The BVP4 is an interesting device that can stay in the past. Use it for rarer restoration VHS projects when needed.

Yes, I've somewhat soured on the device in the past 15 years. Why, you ask? HDTVs, huge LCD computer monitors. Bigger screen, more obvious flaws. CRT hid some BVP4 issues, now not.

Tiny metal screwdrivers are fine, just don't be a hamfisted goon about it. I still like the old saying "tweak it like your lady's nipple", but it's probably very un-PC/sexist/whatever now (and maybe even very untrue these days?). Anyway, gentle, gentle, gentle!

[dpalomaki]

The different colors probably reflect different chips and same color are probably interchangeable within the same pin configuration. I suspect the pots on the board are used to set circuit bias points

The Studio 1 (Sign Video 1996 vintage) Proc Amp did not sand off the IC ID numbers and contained far more internal adjustments. I count 13 trim pots, 14 ICs (12 are 16-pin DIP), and about 20 TO92 transistors on each channel. (Excluding the power supply but including the level meter circuits.)

I'm thinking maybe I should sell the BVP-4 since I've not used it in years.