cr 112 shorting out

[phatt]

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

Thanks Chum, Something strange happening  :loco as only *now* that I've submited another post did I see you actually posted part of the schematic.
WAS not there before???  Oh well no matter, thankyou for the clarification.
Cheers Phil.

[clamup1]

i only posted part of it to keep from getting in trouble with Crate. though the amp is 30 years old i doubt it would matter. that is the assembly schematic. i hope it helps.

[Enzo]

Post whatever you want on this amp, Crate won;t care.

[joecool85]

Post whatever you want on this amp, Crate won;t care.

This is actually true from what I gather.  Crate gives out schematics no questions asked.  Not like Danelectro  :trouble

[clamup1]

the letters on the pic are where i have the wires connected. i have one black from power transformer and the black from the power cord going to the switch. the green wire is attached to a bolt going into the side of the amp.



i hope you guys can see this.

[clamup1]

cool new layout.

anything you guys need to get this amp running?

Merry Christmas, Happy New Year.

[joecool85]

cool new layout.

anything you guys need to get this amp running?

Merry Christmas, Happy New Year.

I guess I'm a bit lost, what's not working on it at this point?

In reference to the TIP122/127 you put in, did you follow this advice?

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.

[J M Fahey]

Don't know on *your* computers, but on mine I click the poetsd schematic and partial layout and the stay stamp size, visible but unreadable.
Am I the only one?

[Enzo]

I thought we had already posted this, sorry, here is the CR112

[clamup1]

i put in the 122 and the 127 the same way the 110, 115 came out.
i was thinking that my prob was starting to sound like the op with the Marshall. i will investigate and get back with you.

*****update**************
the 122 is npn
127 pnp
i believe i got them in right.


here is that section of the board

[clamup1]

hey i was looking at the layout (data sheet) and i think that i have the pnp in backwards. what could or is blown? did i fubar some things up or is it fixable?

[J M Fahey]

did i fubar some things up

Maybe. Probably.

or is it fixable?

On our benches, in 15 minutes.
By remote control?? 
Anyway, it's a pity you messed with it to begin with, because it was originally a nice little garage amp; around 20 W at best, which can not drive 2 12" speakers.
To be more precise it can not drive 4 ohms.
Sorry 

[phatt]

Ouch,, Murphy's law says if there is a wrong way to insert a part then that's usually what's wrong when it refuses to work.

Might be time to invest in a light bulb limiter before you waste money on another set of transistors. 8|
Phil.

[clamup1]

so once i fix this thing, if i unplug one of the speakers it should work right? would having both speakers plugged in when i turn it on blow fuses?

[J M Fahey]

I think *today* your problem is electronic.
Driving 4 ohms will overheat it but might even not burn it, because the power transformer itself is weak.