well guys you got me

I tried to put the three switches in parallel and that works for any one of them turning it on
but none can turn it off

and then the opposite if i put all three in series..

so then i started drawing different combinations progressing to a delta and or wye

so no i dont know.....

but i dont want to cheat and look it up

so I will continue to work on it while watching hockey

 

Quote from: Untilitkills83 on May 08, 2023, 12:58:21 PMGreetings all. Hoping someone might be able to point me in the right direction. I own a Crate BX 160 amp, it is a beast. Recently, when it is powered on, regardless of a bass guitar being plugged in, there is a consistent for lack of a better term 'raspberry' sound coming through the speaker and a minimal / intermittent crackling effect think listening to a record / turntable. All the input and master volume could be turned all the way down and it is still present. When I plug my bass in, all noises remain. If I turn the main volume master and input up, the noise is there but it doesn't get louder. More often than not, the bass can drown it out. I thought I had confined the source to the cable that connects the speaker itself to the main input Jack on the electrical board. After getting a new cable, nothing changed. I've even tried the line out into my preamp interface for recording and luckily it is clean, no raspberry sound or crackling so it would seem that the issue is the connection on the circuit board from where the input Jack is to the main electrical component. Hoping someone might know of a fix for this. Thanks in advance.

I'm re-reading this now and realize that you said the line out is clean.  If this is the case, then it couldn't be related to input whatsoever as this would be evident in lineout.  I'm thinking something is up with the output transistors.

If the volume doesn't change with position of the knobs or anything, I'd be questioning the power supply caps and maybe output transistors.

One of the things you do in early electric/electronic class is learn how to analyze simple circuits usually with a battery, a switch or two and several resistors or light bulbs. You learn how to apply Ohm's Law to calculate Voltages, currents and equivalent resistances. If you skip this step or don't know how to do it, you can look pretty stupid on an internet forum.

Do you know how to hook up a light bulb so you can flip it on of off from two different switches no mater how the other switch is flipped ? How about three switches ?

I have to agree with Phil, too much theory can get in the way if you don't do a lot of practice with real circuits.

I think what would be good for you is to get a breadboard and start building small circuits like stomp-boxes and even small SS amps, and then you can modify them to see what happens in real life with the signal.

You would not need to spend a fortune on parts because you will be able to re-use all the components, just build up a common variety of parts and off you go.

A bread board needs to be a good size to start with, I would buy one with at least 800 points on it.
You can always get another one and use several breadboards for a single build if the circuit is big.
Here is a link to a well priced one: https://www.taydaelectronics.com/hardware/breadboards/830-point-solder-less-plug-in-breadboard.html

I get most of my components from Tayda, if I order resistors I get 50 at a go and then slowly order more values as I need them.
any components that are regularly used I order multiples of them, and if there are better ones for the same price I get the better ones.
One part comes to mind, 1N4001, 1N4004 diodes are used a lot, I get the 1N4007 instead as they have a higher voltage rating but are the same size and price.

Cheers
Mick

Hey chum, unless you intend to build the next space shuttle leave that really hard stuff till later.
If all you want to do is understand Analog Audio Amps then you will learn faster by reading stuff on pages like this;
https://www.sound-au.com/

Open up Articals.
Learn some basics first mate, such as transformers and rectification then move on to basic transistor circuits.

Scroll down to *Beginners Luck*, a lot of good stuff to find there.
Stuff there will help you get your head around the basics.

Be warned you will need weeks to absorb it all as it's a massive site with heaps of good info.
Phil.

I just started another book and it is really good but they immediately had me doing Thevenin and Norton exercises.

I was like "oh no not again plugging and chugging exercises.."

but I guess i will work through it and get to the good stuff...lots of circuits...yeah 

I reckon knowing it will help me somehow down the line

 

All I have is the power amp schematic, I have never seen the pre-amp schematic.
It shows there is a send and return jack so that might be good news.

If the noise disappears when you plug a patch cable from the line out to the line in jacks as Loudthud suggested it means the line in jack is dirty.

The line in jack has a switch in it that disconnects it from the line out jack when a plug is inserted into it, no plug and it is connected to the line in jack.

A quick spray with Deoxit and then insert a plug several times might dislodge the dirt and restore the amp to normal.

You cannot view this attachment.

If the amp has an Effects Loop, try plugging a short patch cord between Send and Return.

sorry I cant help

but welcome to the site

hopefully someone will come along and know how to fix this