cr 112 shorting out

[clamup1]

hey i rehoused a cr112 and made it a cr 212. i have it wired up like this


i dont know if i have it grounded right or whats going on. i dont know anything about amps and didnt know they would be this much trouble.

i have the little black wire from the fuse going to a screw in the side of the box.

the green wire was attached to the chassis before i tore it apart. the pc board was atttached to the chassis.

i took a wire from the screw hole that attached the pc board to the metal and ran it to a screw. the green wire from the power cord is attached here also.

[phatt]

You say you know Nothing about Amps?

Yet you are playing around with the mains :duh

I sense another Darwin Award coming soon 0:)

Take a breath and check you are still alive,,, if so take some better pictures of the wiring then We all have a better chance of helping.

THE GREEN Wire is connected to the case for Safety reasons,,, it's not just their to confuse the ignorant. :trouble

That fuse and White/Black/Black Are mains wires and if you mess up you can kill yourself.
Phil.

[joecool85]

You say you know Nothing about Amps?

Yet you are playing around with the mains :duh

I sense another Darwin Award coming soon 0:)

No need to be rude.  But you do have a good point, it can be very dangerous playing around with mains - even worse if you don't know what you are doing.

[clamup1]

I sense another Darwin Award coming soon 0:)

yes im still alive. lol. i have read the shock hazard warnings on every amp forum ive been to.

that is all the wiring. this is a better pic


the speaker wire is the output for the speakers

this is all the wiring. its all on the left side of the board. there is one black wire from the ps going to the switch and a black wire from the power cord going to the switch

[bry melvin]

The power cord should have black green and white wires:

White goes to fuse
black goes to switch
green goes to chassis

The power transformer black leads go to:

the Other side of the switch
The other side of the fuse

That transformer side of the fuse also goes to a .0027 capacitor which in turn also goes to ground
Hope this helps:

[phatt]

Thanks Joecool point taken,, but I just cringe when I see bad design (i.e. the mains fuse on the edge of a pcb only mm from the audio circuitry)

Then someone with little knowledge trying to modify same can easy leed to premature death. 8|


OK lets get on with it best we can.
Clampup,
I can't see the wiring clearly enough but Bry Melvin may see more than myself.

That Capacitor looking device could be a *Varistor* which would be in series with the mains and not to ground.
If it's a Capacitor then it would be across the mains wires and not to ground.

Here is a pic of what would be close to the wiring you have there.

The secondaries are obviously 2 reds and a black but the primary side you will have to track that yourself, so use my pic as guide only.

If this Amp was in my shed that Mains fuse would be *Permanantly removed* from the Audio PCB and put in a sealed jiffy box away from harm.

But the Main switch is still (I assume) on the front panel which (I assume) is Metal?
If so then the *EARTH* wire needs to be connected to that panel to be safe.

BTW that board looks like it is hanging it's weight from the pots?
If so it won't last long.
Best of luck, Phil.

[bry melvin]

can't see the wiring clearly enough but Bry Melvin may see more than myself.

Actually the info is USING A SCHEMATIC

That Capacitor looking device could be a *Varistor* which would be in series with the mains and not to ground.
If it's a Capacitor then it would be across the mains wires and not to ground.

Again the schematic shows it as a cap and to ground.

I'd post the schematic but the forum keeps telling me it's here already so you might want to search for it.

[joecool85]

I'd post the schematic but the forum keeps telling me it's here already so you might want to search for it.

You could rename the file and then post it.

[clamup1]

thanks for your help. i have the schem on paper and the assembly schem(this one lists the values of caps and resistors) i have this on pdf but i dont know how to post it and i dont think Crate would appreciate it very much.  i talked to Crate and they dont have much info on any of the amps from the early days.

so let me see if i understand you guys correctly

-the green wire from the power cord needs to be connected to the metal panel i have attached to the front of the amp
-i need to figure out which black wire is the main. (on the pic from the led. there is a red wire, red, black from tranny. this black wire is attached to the busy end of the fuse and a .0027uf cap(c40)

Bry- thats how i have it hooked up except for the green wire. thats attached to a screw on the side of my amp(wood)

im wondering if the green wire is why it keeps shorting out

heres the schem

[phatt]

A suggestion.

Open the pdf.
Magnify the area of confusion.
Print screen button (top of keyboard)
Open paint.
Hit Control V.
Save as Jpeg.

Post.

well that's how I do it?
Phil.

[Enzo]

Point of information:

A varistor is a transient suppressor and would not be in series with the mains, it would be across them.

What you are thinking of is a thermistor, an resistor that drops in resistance as it gets warmer.  Those ARE wired in sereis with the mains to reduce inrush current.

ANd this little amp has neither, as pointed out above, that is just a cap.


And on the amp,

WHich black wire is the main?  The one that came up your power cord.  The "mains" is another term for the power in your walls - what you get from the wall outlet.

The green wire from the power cord should be screwed directly to the metal chassis - the primary chassis, not some little sub-panel or extra hunk of metal.  Screw it to whatever the power transformer is bolted to.   Not having the green wire connected represents a possible shock hazzard, but it is not going to make the amp blow fuses.

[phatt]

Thanks for that correction Enzo.

Whoops My thermals are getting mixed with my mistors.

In light of your timely correction then the mustard disc next to fuse is likely a *Thermistor* which are wired in *series with the mains, unless I'm way off again.
(I'm just going on the PCB pic on the first post where the tracks seem to follow that series path)

Either way without better pics or schemo of amp not a lot can be done by anyone.

As to chassis,, My concern is that there is none.
Phil.

[bry melvin]

amp doesn't have a thermistor...just a cap

[clamup1]

hey heres part of the assem schem

from left to right. red wire, red, black tranny. running up right side- black ground, white-power cord
thanks phat. i hope Crate doesnt get mad

what part of the schem do you guys need?


hey on the assem schem they list the TIPs as 120 and 125 (q5 and q6). i put in 122 and 127. found this here
http://www.harmonycentral.com/products/84348
4th and 5th psot down.

if they put these TIPs in and it worked why wont mine work?

[phatt]

Hi,
Well that helps a bit but still I have no idea where the extra black wire went or should go.
Schematic should tell you.

I'd leave it off as (I assume) the amp will work without that cap connected.

As to the power transistors swapping
If you put them in the wrong side the amp will surely blow fuses.

one will be a "npn" device and the other a "pnp" They are polar devices and only work one way.
Make damn sure you get them the right way around.
Phil.