Film-Tech Forum ARCHIVE: Schematic/Diagrams for Ballantyne RX224 amplifier

This is topic Schematic/Diagrams for Ballantyne RX224 amplifier in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Doug Eisemann (Member # 782) on 03-19-2003, 06:34 PM:

Hello, a while back I asked about some mystery Norelco amps, which I think I have figured out. Now I have a more pressing problem. I have a pair of Ballantyne Royal Soundmaster RX224 tube amps with power supply problems. These are monster amps running 881A output tubes, and I don't really want to risk electrocution by powering them up to see what transformer windings are bad. If anyone knows where I could find a schematic or wiring diagram, that would be very much appreciated. I don't believe the manuals section here at film-tech covers the RX224, although I will do some more searching

Thanks
Doug Eisemann

Posted by Ken Layton (Member # 133) on 03-19-2003, 10:43 PM:

Fellow film-techer Dick Prather may have the schematics you need.

Posted by Dick Prather (Member # 1136) on 03-20-2003, 08:13 PM:

I am looking and so far finding nothing. Could you be more specific to tube complement. Sounds like a DI amp probably built by Altec. My older Ballantyne stuff in the 50's shows them using 4 of there regular power amps in parallel. Will keep looking.

Posted by Doug Eisemann (Member # 782) on 03-21-2003, 11:10 AM:

Hello, and thanks for the help so far. The amp has a tube complement as such:
6J5 to 6SN7 phase splitter driving push pull 6B4's interstage transformer coupled to a push pull pair of 5514 transmitter triodes running around 1250 volts on the plates I assume. The amp is a massive split-level design, with the amplifier section on top, and the power supply below. The previous owner said there were some bad power transformer windings, but he wasn't sure which, and I am not about to go sticking my meter in there without knowing exactly what everything in the power supply section is supposed to be doing. Incidentally, one of the amps had 811A tubes in the output section, yet the 5514 has a 7.5v filament instead of 6.3v like the 881A, making me wonder if someone just goofed, or actually modified the filament supply (which it does not look like)
Thank you for any help
Sincerely
Doug Eisemann

Posted by Josh Jones (Member # 447) on 03-21-2003, 11:25 AM:

Could you post a pic of the guts of this beast? My drool awaits [Wink]

Josh

Posted by Doug Eisemann (Member # 782) on 03-21-2003, 12:04 PM:

I will see about that picture. If this works, the pic does not do the amp justice. It weighs around 80 pounds and is actually very neat looking with the massive output tubes.
Not sure if this will work

Posted by Ken Layton (Member # 133) on 03-21-2003, 10:55 PM:

Wow! Now that's an amplifier. [Eek!]

Posted by Paul G. Thompson (Member # 655) on 03-21-2003, 11:07 PM:

Oh, those damned things....

Posted by Josh Jones (Member # 447) on 03-22-2003, 01:45 AM:

oooooooooo.......pretty:)

I likes tubes [thumbsup]

Josh

Posted by Kenneth Wuepper (Member # 1174) on 03-22-2003, 06:33 AM:

Hello, Doug,

I have not touched one of these beasts but have lots of experience with the RCA amps of this type in DI use.

You are lucky to have two units so you can A/B test them. That is you can compare the readings from one to the other. Does either of them work?

You can make preliminary tests of the transformers by:
1. Remove all tubes from the unit
2. Make a test cord for the AC by taking an extension cord and opening one of the leads and insert a lamp socket with switch. This places the lamp in series with the load connected to the cord.
3. Insert the amplifier cord into the extension cord.
4. Install a lamp (100 Watts to start) into the socket and turn it on
5. Observe the brightness of the lamp.
A. Bright light means there is a shorted transformer or line filter
B. Dull glow indicates little power consumption in the amp
C. If there is a bright light, you can determine which transformer is defective by disconnecting the power supply and then lifting the primary lead of each transformer individually, reconnect the power and observe the lamp. The transformer that makes the lamp go dim is the defective unit.

Although this does not always give definite results, it will allow you to service the unit without replacing hand fulls of fuses.

As you zero in on the problem, the wattage of the lamp can be reduced to give a better indication of the load you have created.

Hope this helps. It is also an effective way to test solid state equipment without damaging the unit or replacing lots of fuses.

Good fishing. KEN