Greetings!

I am having a problem with my SCRs on my car battery charger. Its a 12v/6v combo. I have narrowed down my problem to the SCRs on the negative side . I can connect a multimeter pos lead to the postive clamp at the end and then negative lead to the ground on the rectifier by the transformer. This gives me the voltage i am looking for.

I can change the SCRs but it wont be easy! The board is hard to remove or get that. If i bypass the SCRs (connect negative cable to the rectifier) do you guys think i could have problems? I usually just use it for starting.

 

What does the subject SCR do?

 

If you can post pictures of the inside of the charger, any wiring diagrams,or measure the output of the bridge rectifier, that will give you an idea if you can bypass the Thyristor, chances are the Thyristor is for the 6V battery.

 

Greetings!

I am having a problem with my SCRs on my car battery charger. Its a 12v/6v combo. I have narrowed down my problem to the SCRs on the negative side . I can connect a multimeter pos lead to the postive clamp at the end and then negative lead to the ground on the rectifier by the transformer. This gives me the voltage i am looking for.

I can change the SCRs but it wont be easy! The board is hard to remove or get that. If i bypass the SCRs (connect negative cable to the rectifier) do you guys think i could have problems? I usually just use it for starting.

SCRs are fairly likely to have failed short circuit - so they may have already bypassed themselves.

Gate failure isn't impossible - as long as the gate isn't transformer driven; you should be able to inject a small DC current in and see if it triggers.

That will circumvent any regulation, so you need to be careful what you use as a load.

 

Here are the pics

First is the unit, 2nd is the scr that i suspect are dead and 3rd is the scr on the positive side.

 

What does the subject SCR do?

Probably not much after using that charger for starting.................

 

The SCRs read as OL on the meter. The positive one reads around 500 ohms . Will it be a problem if i just by pass them?
get the voltage i need to the battery?

As far as i can tell the scr controls the ground connection.

 

Shorting out the thyristor A/K terminals, will make the AC go directly to output voltage, this would damage the circuit, replacing it with standard diodes like 1N5404 types would be better.

Can you possibly draw a rough diagram of how your battery is connected to the thyristor circuit?

 

The SCRs read as OL on the meter. The positive one reads around 500 ohms . Will it be a problem if i just by pass them?
get the voltage i need to the battery?

As far as i can tell the scr controls the ground connection.

Its probably a bridge rectifier with 2 or all 4 of the diodes replaced by SCRs - linking them will most likely let the magic smoke out.

Patching the SCRs with equally rated rectifier diodes would be less destructive, but the output will not have any regulation and the voltage could be high enough to damage the feedback sensing.