Rockola 1493 Princess amplifier help wanted

I am working to correct a problem on a 1493 amplifier. Symptoms are
are follows:

- When turned on, the amplifier emits a high pitch whistle.
- Sometimes this turns into a loud 'motorboating' sound
- I have disconected the input and connected up a CD player
- You can hear the CD playing but there is still the loud whistle
and sound qulaity is very poor. Volume control has little effect.
- Feeding a signal into either one of the two input pins, or both,
produces the same noise.
- The Bass/Treble & Hum contriols have little effect.
- Connecting a good ground between the two chassis has little effect.
- Hooking up external speakers to the stereo outputs and turning the
switch to 'Stereo' has the same effect. Poor sound quality from the
record playing or a CD from an external player.

What's next to help me diagnose this?

Paul

Paul West wrote:

I am working to correct a problem on a 1493 amplifier. Symptoms are
are follows:

- When turned on, the amplifier emits a high pitch whistle.
- Sometimes this turns into a loud 'motorboating' sound
- I have disconected the input and connected up a CD player
- You can hear the CD playing but there is still the loud whistle
and sound qulaity is very poor. Volume control has little effect.
- Feeding a signal into either one of the two input pins, or both,
produces the same noise.
- The Bass/Treble & Hum contriols have little effect.
- Connecting a good ground between the two chassis has little effect.
- Hooking up external speakers to the stereo outputs and turning the
switch to 'Stereo' has the same effect. Poor sound quality from the
record playing or a CD from an external player.

What's next to help me diagnose this?


You may not like the sound of this, but turn it off and don't turn it on
again until you replace every single capacitor in the amplifier. Also
testing and replacing bad resistors as you go along. Then test every
tube and replace any bad ones. If you are not up to this, there are
many people who rebuild these via mail order. If you feel up to this
task, there are people who sell capacitor kits.

--
Tony