Randall Music - Recent Questions, Troubleshooting & Support

The four speakers are split into two groups left and right. You connect the positive terminal on the upper left speaker to the positive terminal on on the bottom left speaker. Then repeat process connecting negative to negative on the same two left speakers. Then connect one wire from the upper left positive to the positive connector on the jack that is marked 4ohm LEFT on the plate attached to the rear of the speaker cab. The do the same connecting a wire from the negative terminal to the negative terminal on the same left jack. Now repeat the process on the right side in exactly the same way this time connecting to the 4ohm RIGHT jack. The switch that is in-between the two jacks can be set for either channel or for both together for stereo at 8 ohms HOPE THIS HELPS

check the receptacle its plugged into sounds like it may have a loose neutral.

Do NOT use it while this is going on... it may fry the power amp in it. This unit likely uses one of the TDA2050 power amp chips... I could NOT find a schematic. There is probably a failure of the high frequency feeedback loop OR a bad ground in the unit possibly due to a cracked circuit board. First thing is to get a schematic. The Fender frontman 25 uses the TDA1514 chip for the power amp and they have a series 5.6 ohm and .022mfd cap to ground at the output to roll off the response. Also any of the power byppass caps in the vicinity of the power amp would be suspect. This is likely a bad cap rather than a chip, but only troubleshooting will yoeld the answer.

What could be an issue is if the cabinet is a 4 ohm cabinet and you plug it into the 8 ohm output. of the RT100 ... IT WILL BE LOUDER that way... for a LITTLE while... till the power tubes get gassy from overheating and the sound will GO AWAY. VERIFY the impedance of the cabinet and plug into the correct jack on the RT100. Every RT100 will do this... it is GROSS abuse of the amp if you plug 4 ohm speakers into the 8 ohm jack. Some of the power tubes may conduct so heavily when they get gassy that they will cause a hum before total failure. The tubes will first get red, then orange plates and that drives metal ions out of the plates, then they get a purple glow and eventually blow the fuse or something in the power supply.

You may have damaged the variable resistors (the volume controls), you can purchase replacements from a local Electronics store (if UK based try Tandy). Otherwise have you checked the speaker itself for damage? You may have split the speaker which will need to be replaced.

Hi i believe the part number is RAN012

Hope this helps

Kind Regards

KnowHowRebel

Try this outfit:

http://store.amplifiercovers.com/

They do custom work and may already have ones for your units.

If the amp originally failed, it MAY have blown out a circuit protector or fuse in the stack. Check the stack resistance with an ohmmeter. It should probably be around 8 ohms.

The most likely case is that one of the main output transistors (if which there are many) is shorted. When the protect circuit senses DC on the final output, it will not allow the output relay to come on to protect the speakers from raw DC. With the power removed, you can check between each outputs Emitter and Collector and you will probably find close to zero ohms. From that point you need to unsolder each of the pins of the bad channel until you find the shorted device(s) and replace them.

'pianoforte'