Federal Signal PA70 No Sound Output

Hello,

I have an old Federal PA70 that powers on and does emit a sound when I listen really closely to the amp itself, but refuses to emit any sound from a speaker. I don't have the actual 6 pin harness itself, so I've been going off of what I can see from the inside of the controller.

Does anyone know why I am unable to get the siren to emit sound from a speaker? Also, if anyone could let me know where I might be able to find a service manual for it, as I have been unable to locate one online for a wiring guide?

Lastly, if anyone could point me in the right direction for securing or making my own harness that connects to the 6 pin port that have the blades exposed. I already have the other two harnesses, those being the radio integration harness and the controller-to-amp harness.

Thank you for your help.

 

[shues]

Does the connector look something like what appears in this thread but with six pins? If so, then your search terms should include Beau, Cinch, and Jones.

 

[Escalator Slinky]

Does the connector look something like what appears in this thread but with six pins? If so, then your search terms should include Beau, Cinch, and Jones.

After looking at the links provided, it does appear to be a connector for a Cinch Jones Plug/Socket 306-CCT. So thanks for providing the link to that! That only solves one of my problems though.

 

[shues]

Take several high-quality photos of the siren's main circuit board. Folks here can help identify components from the photos. Someone can probably suss out what's what.

 

[Escalator Slinky]

Here's a bunch of photos of both the siren controller and the amp itself. Upon further diagnostic testing, I found that the siren-to-controller cable harness is messed up. You can see in the pictures how it looks like someone messed with the wiring pin ups, it had tons of electrical tape on the harness and plug itself prior to me taking the pictures. The controller itself seems perfectly intact on the inside with no obvious missing or broken connections.

 

[Escalator Slinky]

 

[Escalator Slinky]

Hopefully someone can tell me how the plug is supposed to be wired. Ideally if anyone could link some schematics, that would be most appreciated!

 

[Escalator Slinky]

So after a lot of trial and error, I've found what was the ultimate cause of it not working. The wire that was attached to what appears to be an audio transformer was hanging on by a literal thread of copper. Here are the photos of the component after I took out of the amp since I managed to accidently damage it while de-soldering the old wire. There are no manufacturer marks anywhere on it, only a set of part numbers.

Does anyone know where I can get a replacement for this part? I don't know any of the values (ohms, resistances, outputs, inputs, etc. whatever this thing needs) nor who would still manufacture something like this.

 

[shues]

I see that 120B123 is a Federal Signal part number, and it appears in several service manuals including https://www.fedsig.com/sites/default/files/resource_library_document/255A112.pdf

 

[Escalator Slinky]

I see that 120B123 is a Federal Signal part number, and it appears in several service manuals including https://www.fedsig.com/sites/default/files/resource_library_document/255A112.pdf

Well, it's a good start! It would've been nice if Federal had listed who manufactured the part itself. Trying to search that part number on google gets virtually nothing except for the PA15 and PA20 service manuals, which don't give any more info about the part.


edit: bump
I thought hitting the "bump" button would've actually just done a separate new message that says "bump" instead of re-posting this message again over the original. This reply was originally posted on ~November 25 / 26

 

[Escalator Slinky]

Still looking for a replacement. Does anyone have any more information on who made the original transformer? Or at the very least, a modern equivalent that will work?

 

[shues]

This may sound silly considering the age of the siren, but seriously, try calling Federal Signal. Exercise patience and you might get access to more documentation than can be found online.

 

[shues]

I looked again and found Federal part number 120B123 in six manuals currently on fedsig.com: PA-15A Series 1E, PA-20A Series B, PA-20 Series 2E, PA-150, PA-200, and JetSonic.

In each of these sirens, the 120B123 seems to be used for the radio rebroadcast function. Is the 120B123 in the radio rebroadcast circuit in the PA-70? If not, in which circuit is the 120B123 used?

 

[Escalator Slinky]

I looked again and found Federal part number 120B123 in six manuals currently on fedsig.com: PA-15A Series 1E, PA-20A Series B, PA-20 Series 2E, PA-150, PA-200, and JetSonic.

In each of these sirens, the 120B123 seems to be used for the radio rebroadcast function. Is the 120B123 in the radio rebroadcast circuit in the PA-70? If not, in which circuit is the 120B123 used?

Very very very late reply, but I will look into calling federal to see if they have anything on it. As for the circuit, from what I can tell based on when I testing it to make it work, that transformer seemed to be linked in somehow. When the original wire that was on there was moved around, it would make it work sometimes. So it very well could be for the radio function, but until I mess around with it more, I can't be certain.

 

[Escalator Slinky]

If you look at "Amp Top Down View Open.jpg" you will see the transformer itself with a silver wire coming off of it, just above the large transformer with the black "TEST" written on it.

 

[Wailer]

Well, it's a good start! It would've been nice if Federal had listed who manufactured the part itself. Trying to search that part number on google gets virtually nothing except for the PA15 and PA20 service manuals, which don't give any more info about the part.

Those manuals are actually for the PA15A series 1E and PA20A series 2E, both of which were manufactured in the 1970s. Federal made a lot of them, and that is likely why the service manuals are still available. The PA70 and PA100 were manufactured from about 1972 to 1978, and they weren't as popular.

 

[Jack Jones]

Hello,

I have an old Federal PA70 that powers on and does emit a sound when I listen really closely to the amp itself, but refuses to emit any sound from a speaker. I don't have the actual 6 pin harness itself, so I've been going off of what I can see from the inside of the controller.

Does anyone know why I am unable to get the siren to emit sound from a speaker? Also, if anyone could let me know where I might be able to find a service manual for it, as I have been unable to locate one online for a wiring guide?

Lastly, if anyone could point me in the right direction for securing or making my own harness that connects to the 6 pin port that have the blades exposed. I already have the other two harnesses, those being the radio integration harness and the controller-to-amp harness.

Thank you for your help.

On the PA70, this symptom usually points to the 6-pin harness not properly enabling the amp rather than a failed output stage.
These units typically need more than just power and ground the 6-pin plug also carries an “enable/remote” line and mode/control signals. If the enable pin isn’t correctly set, the amp can power up and produce faint internal audio but keep the speaker output muted.
Before building a harness, it’s important to confirm the exact pinout for your PA70 variant, as Federal Signal changed assignments across revisions. Without the correct enable/sense wiring, the unit will stay in standby or mute mode even if everything else is working