MaCo 200 Ameteur - How to test it?

[eel_dahc]

Hello all, I just signed up to see what to do with this MaCo 200 Ameteur amp that I just received. It had been in the back of a great uncles office for over ? years. He didn't even remember what it was. He is 84 yrs old so I guess it's ok if he forgot.

This thing looks brand new and has the clear plastic protective covering on the front.

The thing is, when I looked it up online, I found this site and a thread about the settings and warming up the tubes and the post was conflicting. Well, I know nothing about these and when it comes to something that I don't know concerning old electronics, I try to get all the procedures so that I don't fry it. What I would like to ask you pros is :

How do I go about turning this thing on in a safe way to make sure that it works?

I haven't opened it up to look inside yet.

What should I do to begin?

 

[wavrider]

Hello and welcome to the forum.

I have rebuilt some maco 200 amps, sweet little amps.

There is a thread on this site titled how to tune an amp. Do a search and you should be able to find it. That will get you to the tune part.

The part about how to test it.

First look and see if the fuse is still good. That will at least let you know if the amp might have been in working condition when put away many years ago. Also look at the amp rating of the fuse. hopefully it is not a 20 amp.Somewhere in the neighborhood of 7 to 10 amp should be about right. the schematic will tell you exactly what it should be.

I would strongly recommend taking it to a repair shop, local cb place or if you know anyone that is in the radio hobby to have them look at it.

The filter capacitors, if original, will be old and need to be brought up slowly on a variac, a piece of equipment that allows you to vary the amount of input voltage to the amplifier. sort of like a dimmer switch on a light for an example.

If you plug it in and turn the power switch on it may or may not cause some arc and spark excitement. As the filter caps will show a dead short and probably take a few of the rectifier diodes out with the current draw. By slowly bringing the voltage up with the variac it allows the capacitors to build back up per say.

It would also be a good idea to have the tubes tested on a tube tester, you may or may not find that in a repair shop.

the schematic can be found at CBtricks.com website.

It is a sweet little amp and hopefully you will be able to get it tested and put back into service.

If you are not familiar with electronics then do not take the cover off of that amplifier as there are lethal voltages in the power supply section.

 

[eel_dahc]

Thanks Waverider. I'm thinking of selling it but, I am uneasy about that since, I really don't how it is. It might be fine, maybe not. But, I will check what you've mentioned.

 

[wavrider]

Thanks Waverider. I'm thinking of selling it but, I am uneasy about that since, I really don't how it is. It might be fine, maybe not. But, I will check what you've mentioned.

It is vintage equipment, you can put it on an auction site as is for parts and repair and then let the bids fall where they may.