VB 8 - A VIBRATOR test

Radio Telephone and Telegraph Transmitting and Receiving Equipment
Post Reply
Sergeant Major of the Gee
Sergeant Major of the Gee
Posts: 369
Joined: Sun Feb 01, 2009 11:15 am
Location: FRANCE

VB 8 - A VIBRATOR test

Post by packer » Thu Mar 14, 2019 3:23 am

Hi all how to test a vb8 a 7 pin vibrator 6 volt , and a vb- 9 - a ,,, 4 pin 2 volt vibrator out of the radio ,,,BC 728 radio thank you colin

User avatar
Posts: 1843
Joined: Fri Aug 05, 2011 10:45 am
Location: near Namur, Belgium

Re: VB 8 - A VIBRATOR test

Post by YLG80 » Thu Mar 14, 2019 6:22 am

VB-8-C : I would put 2V DC on pin 7 and pin 4
VB-9 : 2V DC on pin 1 and 2.

If it does not start vibrating you could try to shake the vibrator for a while in the palm of your hand.
1)Take the vibrator in your right hand from the pin side.
2) Knock the palm of your left hand and continue while rotating the vibrator.
3)When your hand is almost in flames you are likely done. (If you don't want to use your hand, knock the vibrator on a piece of rubber or the tire of your bicycle :))
If it does not vibrate again, restart 1) :D

It's always better to replace these old vibrators guts with semiconductors.
Not sure, but a 2 volts solid state vibrator has yet to be developed.
Why not with the modern low voltage electronics used in the portables devices? Difficult though.
See also: http://www.mapleleafup.net/forums/showt ... hp?t=28377
Last edited by YLG80 on Mon May 06, 2019 6:18 am, edited 2 times in total.
Ford GPW 164794 1/4T 12-7-43 - Frame# GPW*239762*
ACM I body#198443
Restored as 1st Army 759th LT B21

G-Private First Class
G-Private First Class
Posts: 11
Joined: Mon Dec 15, 2014 7:31 am
Location: Vegas

Re: VB 8 - A VIBRATOR test

Post by mkiispit » Sun May 05, 2019 11:29 am

I have 4 of these and they work flawlessly.

User avatar
CWO4 (Ordnance) USNR
Posts: 2029
Joined: Sun Dec 29, 2002 1:22 pm
Location: USA/TX/Houston

Re: VB 8 - A VIBRATOR test

Post by wa5cab » Thu May 16, 2019 10:28 pm

The instructions below for the VB-8-(*) are correct as far as they go.The coil was made to run off of 2.1 VDC, Pin 4 does go to the top of the coil, and pin 7 does go to the far side of the interrupter contact which is in series with the coil. If the vibrator already works, it will vibrate. However, something must be connected to four of the remaining five pins to indicate whether the other four contacts are working or not. It is quite possible for the interrupter contact to work but the power supply not to work because some or all of the other four contacts aren't working. So the AC Line and light bulb method should be used. If the vibrator is OK, it will give an immediate indication of that. If it isn't OK, in about 95% of the cases this method will eventually fix it.

However, the instructions for the VB-9 probably won't do anything and if it does, will short out the power supply or battery and probably weld one of the contacts closed.

First, the operating voltage range of the VB-9-A is 5 to 15 VDC, not 2 VDC. The VB-9 is the battery charging vibrator for the PE-157 and the BC-728, So it can be used with either a 6 or a 12 volt battery or battery charger or in either 6 or 12 volt vehicles.

Second, by about mid-War there were two basic types of vibrators in use, called Series and Shunt. Some vibrators were made only in one type, and others were made in both. The VB-9-A was made in both, and both had the same Signal Corps Stock Number. The power supplies that used both would run with either type without anything being changed in the supply (no switches, etc.). The Series type had one contact set for the coil and 2 to 5 sets for the power supply or supplies. Either type would work either with a separate rectifier or (if there were enough contacts) as self-rectifying (Synchronous).

The Series type has battery voltage applied directly to the coil, has one normally closed (NC) contact for the coil and two or more for the transformer(s). The shunt type does not have a coil contact. It draws coil current through the transformer primary. All of the contacts are NO. One contact that closes when the coil is drawing current is chosen as the coil contact. All contacts are connected to the transformer. When power is first applied, the coil starts drawing current and pulls the armature to one side, closing half of the contacts, including the one connected across the coil, which shorts out the coil. This releases the armature whose spring starts the armature moving toward the opposite set of contacts.

However, if you connect the battery to pins 1 and 2 on a VB-9, nothing will happen if it is a Series type (the coil is on pin 4). If it is a Shunt type, you will short out the battery or power supply. There is no way to test a Shunt type vibrator by simply connecting a battery to it.
USN Retired
MVPA 9480

Post Reply

Return to “Radio's and Communications”

Who is online

Users browsing this forum: No registered users and 50 guests