Re: Rock ola 474 amp

On 2020/08/12 12:26 p.m., Dave N. wrote:
> John Robertson;700563 Wrote:
>> On 2020/08/10 12:37 p.m., Dave N. wrote:-
>> I just pick up two Rockola 474's and the one I'm working on has static
>> in the right speaker all the time sometimes you can hear it over the
>> music. I have replaced most all of the electrolytic capacitors on the
>> driver board, the pre amp and the power board with no change in the
>> noise. has any one ever had this before.
>>
>> Thank you for your help
>>
>> Dave Niccum
>> Georgetown, Il USA
>>
>>
>>
>> -
>>
>> Unlikely to be a capacitor, more likely a resistor or transistor or even
>>
>> a noisy electrical connection.
>>
>> First, try unplugging the input to the amp. If that solves the noise
>> then check the cartridge and wiring.
>>
>> When you adjust the volume does the noise go up/down with it?
>>
>> If yes, then the problem is either the volume control or in the
>> pre-amp.
>>
>> If it doesn't change then the problem is most likely in the power amp
>> section.
>>
>> An audio signal tracer is what you want to track that down!
>>
>> John :-#)#
>>
> 
> Thank You I will check it out
> 


Hi Dave,

These tests are done when the machine is playing a record and you are 
hearing the noise...

John :-#)#

-- 
(Please post followups or tech inquiries to the USENET newsgroup)
                      John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
          (604)872-5757 (Pinballs, Jukes, Video Games)
                      www.flippers.com
        "Old pinballers never die, they just flip out."