B61 Electrical Help

[wingman]

Hi, I bought a 1959 B-61 that I need a little help to determine what voltage and ground it's supposed to be. It is currently wired for 24v and positive ground. Is this correct? It has a rebuilt starter and works very well, almost too well as it turns the engine over very fast. Makes me think it should be 12 volts. It shows no charge on the ammeter, and when I put a volt meter on it, also no charge. I haven't as of yet found a manual or wiring diagram for it, so until I do can anyone give me some insight? Thanks, Bob

[Rob]

Hi, I bought a 1959 B-61 that I need a little help to determine what voltage and ground it's supposed to be. It is currently wired for 24v and positive ground. Is this correct? It has a rebuilt starter and works very well, almost too well as it turns the engine over very fast. Makes me think it should be 12 volts. It shows no charge on the ammeter, and when I put a volt meter on it, also no charge. I haven't as of yet found a manual or wiring diagram for it, so until I do can anyone give me some insight? Thanks, Bob

Naw, she is 12VDC with 24VDC start. It should be positive ground unless it has been changed. With the engine wanting to fly off the mounts when you hit the button says the series/parallel switch under the cover on the floorboard is working well. You will appreciate that fast starter if trying to start the truck in cold weather not plugged in.......

Chances are your regulator on the firewall on the driver's side is the issue. Whether the problem lies in wiring, or actual parts I do not know at this point. If the vehicle sat for a long time without being ran, the electrical generator may need to be repolarized. First thing I would do is while the truck is idling, clip a wire on the post that holds the cable running to the battery negative post, (if positive ground). Momentarily touch this jumper wire to the "F" terminal on the generator, (you may see a spark) then check for a charge condition at a high idle. Once you apply voltage to the terminal you have "excited" the fields within the generator and the soft iron core of the armature will retain the magnetism so it won't need repolarized again.

If this doesn't get you to charging start to trace out the wiring and don't rule out replacing the voltage regulator. They are not that expensive and a new one will be pre adjusted to proper voltage and current output. Best nowadays to convert to an alternator but it's not necessary.

Barry has posted a wiring diagram of the electrical in the help sections within the website.

Rob

[wingman]

Naw, she is 12VDC with 24VDC start. It should be positive ground unless it has been changed. With the engine wanting to fly off the mounts when you hit the button says the series/parallel switch under the cover on the floorboard is working well. You will appreciate that fast starter if trying to start the truck in cold weather not plugged in.......

Chances are your regulator on the firewall on the driver's side is the issue. Whether the problem lies in wiring, or actual parts I do not know at this point. If the vehicle sat for a long time without being ran, the electrical generator may need to be repolarized. First thing I would do is while the truck is idling, clip a wire on the post that holds the cable running to the battery negative post, (if positive ground). Momentarily touch this jumper wire to the "F" terminal on the generator, (you may see a spark) then check for a charge condition at a high idle. Once you apply voltage to the terminal you have "excited" the fields within the generator and the soft iron core of the armature will retain the magnetism so it won't need repolarized again.

If this doesn't get you to charging start to trace out the wiring and don't rule out replacing the voltage regulator. They are not that expensive and a new one will be pre adjusted to proper voltage and current output. Best nowadays to convert to an alternator but it's not necessary.

Barry has posted a wiring diagram of the electrical in the help sections within the website.

Rob

[wingman]

Thanks for the help Rob. It gives me a little more insight as to what I'm dealing with. I am new to the site and was unable to find the diagram you mentioned in the help section. I searched for B61 wiring diagram and nothing came up. Any ideas? I can see I have my work cut out for me with this beast. I am used to military 24v systems, which are more cut and dried, but I always like learning something new!

[rhasler]

Thanks for the help Rob. It gives me a little more insight as to what I'm dealing with. I am new to the site and was unable to find the diagram you mentioned in the help section. I searched for B61 wiring diagram and nothing came up. Any ideas? I can see I have my work cut out for me with this beast. I am used to military 24v systems, which are more cut and dried, but I always like learning something new!

It's under the wiki tab at the top of the screen. Click wiki, click antique and classic Mack truck articles, click antique and classic Mack info. It should be the last entry on the first page.

[wingman]

It's under the wiki tab at the top of the screen. Click wiki, click antique and classic Mack truck articles, click antique and classic Mack info. It should be the last entry on the first page.

[wingman]

It's under the wiki tab at the top of the screen. Click wiki, click antique and classic Mack truck articles, click antique and classic Mack info. It should be the last entry on the first page.

Thanks, I found it. Always ready to learn something new.

[wingman]

Rob, is the voltage regulator and generator supposed to operate at 12v or 24v? Is there an easy way to convert the whole mess to 12v, either + or - ground? I read your reply on polarizing the generator, but I'm not sure if you polarize it with 12v or 24v. Kind of a confusing setup!

Thanks for your help, Bob

[Rob]

Rob, is the voltage regulator and generator supposed to operate at 12v or 24v? Is there an easy way to convert the whole mess to 12v, either + or - ground? I read your reply on polarizing the generator, but I'm not sure if you polarize it with 12v or 24v. Kind of a confusing setup!

Thanks for your help, Bob

All is 12VDC. The series/parallel switch puts the 12VDC batteries in a series configuration to supply 24VDC to the starter motor. The voltage regulator, and generator is 12VDC and most likely positive ground if original.

Rob

[wingman]

All is 12VDC. The series/parallel switch puts the 12VDC batteries in a series configuration to supply 24VDC to the starter motor. The voltage regulator, and generator is 12VDC and most likely positive ground if original.

Rob

Thanks Rob for the help. Everything appears to be original except the previous owner had spliced a wire with 24v to the bat side of the regulator. It probably fried the regulator but until I can get the time to play and connect the proper wire using the wiring diagram, I won't be able to tell what's damaged. Also looking at the wiring diagram I got in the wiki section, the wire connections to the batteries don't show the polarity of the battery posts. Not to trouble you but can you tell me from that picture the polarity of which wires to which posts so that I can first make sure the batteries are connected properly. Always start at the source and work your way out! Thanks again for the help, Bob

[Rob]

Thanks Rob for the help. Everything appears to be original except the previous owner had spliced a wire with 24v to the bat side of the regulator. It probably fried the regulator but until I can get the time to play and connect the proper wire using the wiring diagram, I won't be able to tell what's damaged. Also looking at the wiring diagram I got in the wiki section, the wire connections to the batteries don't show the polarity of the battery posts. Not to trouble you but can you tell me from that picture the polarity of which wires to which posts so that I can first make sure the batteries are connected properly. Always start at the source and work your way out! Thanks again for the help, Bob

If you will PM me a fax number i'll send you a diagram that is easy to follow for hooking these up. I've made a "cheat sheet" for just such a purpose. Not sure what you mean with the ancillary wire mentioned as there is not 24VDC available in the system until engine crank is initiated. Then that voltage is only applied to the starter motor and nowhere else.

Rob

[wingman]

If you will PM me a fax number i'll send you a diagram that is easy to follow for hooking these up. I've made a "cheat sheet" for just such a purpose. Not sure what you mean with the ancillary wire mentioned as there is not 24VDC available in the system until engine crank is initiated. Then that voltage is only applied to the starter motor and nowhere else.

Rob

Not sure what you mean by "PM", but how about scanning as an attachment by E-mail? I do have a fax but it uses my home phone and have to set a time to snd so I can turn the machine on.The wire that was attached to the Batt terminal on the regulator was clearly not original and was reading 24v on a volt meter, so that alone makes me suspect how the batteries are connected. I haven't had time to trace back the cables to the switch, but I want to make sure everything is connected correctly. Electrical fires aren't fun. Bob

[Rob]

Not sure what you mean by "PM", but how about scanning as an attachment by E-mail? I do have a fax but it uses my home phone and have to set a time to snd so I can turn the machine on.The wire that was attached to the Batt terminal on the regulator was clearly not original and was reading 24v on a volt meter, so that alone makes me suspect how the batteries are connected. I haven't had time to trace back the cables to the switch, but I want to make sure everything is connected correctly. Electrical fires aren't fun. Bob

I don't have a scanner that works or that would be my preference also.

"PM" means private message. I don't mind sharing my phone number but others don't care to for privacy reasons.

I can't think of a reason you would have 24VDC available unless something is connected incorrectly. Most regulators have the voltage either silkscreened, or stamped into them but due to age this could be very difficult to ascertain.

Thanks,

Rob

[wingman]

I don't have a scanner that works or that would be my preference also.

"PM" means private message. I don't mind sharing my phone number but others don't care to for privacy reasons.

I can't think of a reason you would have 24VDC available unless something is connected incorrectly. Most regulators have the voltage either silkscreened, or stamped into them but due to age this could be very difficult to ascertain.

Thanks,

Rob

How do you send PM on this site?

[Rob]

How do you send PM on this site?

Under the avatar photo to your left there is a photo that looks like an envelope with the flap open. Click on that to send a message.

Rob