Schauer charger

[Mike(NEOhio)]

6/12 volt deep cycle model. No output and I get a spark when I connect the leads to a battery with the charger off. I'm trying to test and repair it but can't find a schematic for that model online. Schauer has not responded to my question. Can anybody help?

 

[Janicholson]

The spark is not allowable. Make sure the connection is in correct polarity Red+ black- . If it is connected correctly, The charger may need a new set of diodes. Check those with the diode disconnected at one terninal. Many new chargers assess the battery for some charge, even as low as 2 volts. If the battery is stone dead, they do not charge.

 

[Mike(NEOhio)]

The spark is not allowable. Make sure the connection is in correct polarity Red+ black- . If it is connected correctly, The charger may need a new set of diodes. Check those with the diode disconnected at one terninal. Many new chargers assess the battery for some charge, even as low as 2 volts. If the battery is stone dead, they do not charge.

I didn't think that spark was right. I'm not getting any voltage at the clamps either on 6 or 12. I went to use it on a six volt last week and it showed about 4-5 amps but tapered off to nothing quickly. If I wiggled the wires at the strain relief it jumped to 5 and dropped to 0 again. At the time I was getting 14.5v at the clamps on 12 and 10.5 on the 6 setting, way too high. When I opened the case I found on of the spade connectors of the output cord was burned. I put a new one on and now I get nothing.

 

[Mike(NEOhio)]

The spark is not allowable. Make sure the connection is in correct polarity Red+ black- . If it is connected correctly, The charger may need a new set of diodes. Check those with the diode disconnected at one terninal. Many new chargers assess the battery for some charge, even as low as 2 volts. If the battery is stone dead, they do not charge.

I tried again, got a small spark when I connected the leads to the battery and I heard a small click, I think the breaker. I get a spark when I brush the clamps together but I cant get a voltage with my meter. Which one is the diode? I'm not a wirehead. The lead coming down to the left end of the higher block is from the ammeter, the other to the lower plate comes from the transformer. The second on the lower, next to the insulated one is from the transformer. Can't get a reading at either one.

 

[Brownie450]

Top device is the circuit breaker.
Lower 2 wires are from the transformer. They connect
to the diodes on the heat sink. Unfortunately those are
"button" diodes used in many automotive alternators.
They tend to short upon heating from over charging.
You need to pull off the 2 transformer wires to check
what Voltage you are getting from the trans.
You should have a diode checker on your multimeter
down by the Ohms selector. With both trans leads off,
check the diodes by holding the leads one way, & then
reverse the leads. Each diode should read infinity in one
direction & around 500 to 600 in the other if good. Any
other readings indicate bad diodes.
I'd also check the battery leads for continuity using
your multimeter. Flex the leads especially at the strain relief
to see if there is an open or intermittent connection.
Jim

 

[Mike(NEOhio)]

Thanks for the help. The uninsulated connection on the left of the breaker comes from the transformer as well as the two on the diodes. I looks to me like that one is the common. Should I check the voltage from each of the two on the diode to that one, or across the two on the diode?

 

[Brownie450]

Yes, check Voltage on each wire to the negative single
wire from the trans, which is the trans negative [center
tap]. You can check Voltages from each "hot" lead to
each other. They will be 2 times what is found on the
hot wires to the center tap.
If nothing is found on the low voltage side, you might
see what incoming AC Voltage is at the power cord.
Should be on the order of 120 Volts.
Jim

 

[wore out]

I tried again, got a small spark when I connected the leads to the battery and I heard a small click, I think the breaker. I get a spark when I brush the clamps together but I cant get a voltage with my meter. Which one is the diode? I'm not a wirehead. The lead coming down to the left end of the higher block is from the ammeter, the other to the lower plate comes from the transformer. The second on the lower, next to the insulated one is from the transformer. Can't get a reading at either one.

Looks like you have the (+) charging wire AND a transformer lead on the diode on the right?

If so, that is NOT correct, the (+) charging lead should be connected to a common point on the circuit board where the cathodes of the two diodes are connected.

 

[Mike(NEOhio)]

The diodes seem to be OK but they look like both tabs on each one are a common piece.. I scraped the crud off the tops and there is a dot in the center of each one. I have incoming 120v because I can hear the timer motor running. Just can't find any voltage from the transformer.

 

[wore out]

The diodes seem to be OK but they look like both tabs on each one are a common piece.. I scraped the crud off the tops and there is a dot in the center of each one. I have incoming 120v because I can hear the timer motor running. Just can't find any voltage from the transformer.

Did U read reply #8, it CAN'T function the way you have it connected.

 

[Mike(NEOhio)]

Did U read reply #8, it CAN'T function the way you have it connected.

That's how it was when I opened it up. Pretty sure it worked last time I used it. I did read your reply but didn't quite understand it. The two prongs on each diode look like they're one piece but check OK with the multimeter. Left prong is the anode on both. Is that correct? The two wires are from the transformer, I assume one is 6v, the other 12v. The wire on the left of the breaker is from the transformer and wrapped around the ammeter. I replaced the battery wires and clamps a while back and was real careful to get the polarity right and I think I got the connections right. I always worked.

 

[Brownie450]

Show a front view of the charger. If there is a slide
switch for selecting voltage, they are prone to failure.
Prove out that you are getting 120 Volts into the
transformer primary leads.
You were talking timer motor, so check out that you are
getting 120 Volts at the timer contacts going to the
trans.
Jim

 

[Mike(NEOhio)]

Show a front view of the charger. If there is a slide
switch for selecting voltage, they are prone to failure.
Prove out that you are getting 120 Volts into the
transformer primary leads.
You were talking timer motor, so check out that you are
getting 120 Volts at the timer contacts going to the
trans.
Jim

It has a rocker switch for 6 or12 and I can hear or feel the timer motor running. There is a bunch of wires on the primary side of the transformer. I'll get some pictures later today.

 

[wore out]

It has a rocker switch for 6 or12 and I can hear or feel the timer motor running. There is a bunch of wires on the primary side of the transformer. I'll get some pictures later today.

Above is a diagram of how the diodes in a battery charger with a center-tapped transformer would typically be connected.

Here's how it looks to me you have connected yours.

 

[Mike(NEOhio)]

Got back to it today with a clear head and did some testing. I have 121.5v at the center post of the 6-12 selector.
With the switch at 6v I have 121.5 at the lower post and 76.9 at the upper post
With the switch at 12v I have 121.5 at the upper post and 191.8 at the lower post.
Then I had a DUH moment and realized when I previously got no voltage from the transformer I was looking for DC before the diodes. Using AC I get 8.1 and 12.9 at both leads to the common. So everything seems to be working up to there.
Checking the diodes again the left one is .5 ohms and I but the right one is .4 both ways.

 

[Brownie450]

Diode being ,4 both ways indicates a shorted one. Short your
meter leads in the Ohms setting & see what they read. The
resistance of the leads has to be factored in when checking
diodes or resistance. That's why the fractional readings.
Jim

 

[Mike(NEOhio)]

Diode being ,4 both ways indicates a shorted one. Short your
meter leads in the Ohms setting & see what they read. The
resistance of the leads has to be factored in when checking
diodes or resistance. That's why the fractional readings.
Jim

I see what you mean in your drawing. Seems that it would need a jumper between the two cathodes. I worked on this some years back but only replaced the battery leads and clamps. I wouldn't have removed anything ahead of those connections, just left everything else alone.

 

[Mike(NEOhio)]

I think I found my mistake. I got the diode off the base and noticed the red dot from a sharpie that I put on it when I replaced the leads. That tab on the plate is clean and tinned while the other two have black paint on them. I think I should have put the + battery lead on that tab. Is the the cathode for both diodes?

 

[Brownie450]

Both diodes are common to the heatsink & positive output lead.
Your first pic shows the wiring is as it should be.
Jim

 

[Mike(NEOhio)]

This morning I figured WTH and put the diodes back in with the output lead on the heat sink tab.
With selector OFF

Selector on 6v

Selector on 12v

Now I'm really confused. But it works.