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Anyone know what B+, VCP and ABL markings mean?

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Steve Hobley

Tue Dec 21 2010, 12:50AM

Registered Member #1731 Joined: Thu Oct 02 2008, 02:22PM
Location: Indiana
Posts: 52

I have a flyback taken from an old Gateway monitor - it's marked

6174Z-1038A
1AJ 09

On the PCB the terminals are marked with output voltages and ABL, VCP and B+.

Anyone know what they mean?

Steve

Dr. ISOTOP

Tue Dec 21 2010, 01:18AM

Registered Member #2919 Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652

Here's the answer, according to Yahoo Answers:

1.180V------------------------supply to video circuits
2.Heater----------------------tube's heater supply
3.nothing
4.25V------------------------- etc
5.B+---------------------------main supply voltage from power supply
6.ABL--------------------------beam limit
7.COL-------------------------collector of HOT
8.AFC------------------------ etc
9.GND
10.nothing

Steve Hobley

Tue Dec 21 2010, 09:54AM

Registered Member #1731 Joined: Thu Oct 02 2008, 02:22PM
Location: Indiana
Posts: 52

Hey thanks for the reply - I did see that, but does anyone know what beam limit actually does, and VCP is not mentioned

Antonio

Tue Dec 21 2010, 01:32PM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

Find the schematic of the board. Usually the pins below are the primary coil, several other coils to generate other voltages, one of them used as feedback to regulate the output, and ground pins for the main coil, potentiometers, filter capacitors and bleeder resistors.

Steve Hobley

Tue Dec 21 2010, 01:44PM

Registered Member #1731 Joined: Thu Oct 02 2008, 02:22PM
Location: Indiana
Posts: 52

I've been looking for a schematic, but the usual places aren't turning anything up - I can see it listed as a part on the manufacturer's site, but no schematic.

Antonio

Tue Dec 21 2010, 08:30PM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

Try this site for the schematic:

Xray

Tue Dec 21 2010, 09:54PM

Registered Member #3429 Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288

Steve Hobley wrote ...

I have a flyback taken from an old Gateway monitor - it's marked

6174Z-1038A
1AJ 09

On the PCB the terminals are marked with output voltages and ABL, VCP and B+.

Anyone know what they mean?

Steve

The marking labeled "B+" originated from the old days when vacuum tube circuits were battery powered. The filament supply was called the "A Battery", the plate (anode) supply was called the "B Battery", and the grid bias supply was called the "C Battery". When TV's became powered by the AC line, engineers continued using the B+ designation for the high positive voltage (generally a few hundred volts) that fed the plate circuits. Since the filaments were powered by a low voltage winding on the power transformer, the "A" designation was no longer used. Also, the "C" designation was no longer used for the grid bias supply.

ABL stands for Automatic Beam (or Brightness) Limiter. It's a circuit that limits the brightness of the CRT in order to prevent the phosphor from getting burnt. You can find patents and other detailed information about it's function by searching on Google.

Th3_uN1Qu3

Sat Dec 25 2010, 11:27AM

Registered Member #2614 Joined: Sat Jan 09 2010, 08:57AM
Location: Bucharest, Romania
Posts: 26

Now coming to what you're actually interested in - the B+ winding is of use to you only if you plan on using a mains-powered driver as it needs to get at least 130 volts to generate any useful HV. If you intend to power your driver from 12 volts, you need to do your own primary winding. Most flybacks have some of the core exposed for deriving the heater winding, so that won't be a problem. Start from 6 turns and go down - the less turns the higher the output voltage, but go too far and you'll ask for too much current from the switching device and blow it.

I used to run a flyback from a 17" monitor with a IRF640. I used 4 primary turns and never fried the MOSFET, but the heatsink it was installed on used to cool ALL the power transistors in that monitor so it was quite big.

UbuntuNinja

Tue Dec 28 2010, 04:07AM

Registered Member #2677 Joined: Mon Feb 08 2010, 03:06AM
Location: Palo Alto, California, USA
Posts: 64

While we are on the subject of flyback transformers, does anyone know any good tricks for figuring out which of the many sequences of numbers marked on a flyback transformer is the specific part number (i.e. the number that could be used to find a datasheet)?

Ash Small

Tue Dec 28 2010, 04:23AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Can you post some photos of it (including numbers)

Do you know the make of the flyback?

(the make of the TV/monitor it came from may also be useful)

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