crate:
loudtechnologies.com
25001h4_.pdf (511.6 KB)

Hello teemuk,I dont know If I can post this schematic or down load it to this forum.The information (above) is Adobe Reader.I obtained the schematic through loud technologies.Its a crate,GTX410 triode .Yes the amp is functional,I can play it but it makes one heck of a hissing noise.Im just a guitar player,but Im leaning toward the opamp also or at least that has crossed my thoughts.I havent done a volt test on the transformer and power supply yet!I will do that!I was working on my Boss me 50 and traced it down to a cracked board in between the inputs (mono and stereo)female inlets.Someone stepped on the 1/4 jacks.Its (trash).I had to pull off the crate to give that some attention.Hey, I really appreciate your efforts,You know what your talking about.When I first bought this amp,It had a hiss in it when I played it.As time has gone by,The hiss is more prominent.Im not a tech but willing to learn.Im going to read over your last post again and take it to heart.If you can get a chance to look up the schematic I would be grateful ! Thanks alot for your help.  ADV

Hello, Thanks for the response,Nashville Bill,Teemuk, and Jack1962.The amp has a loud hiss with the speakers hooked up,with amp on.Then I unhooked the speakers and there is a slight faint hiss.Yes, I turned off the amp when I did each test,Tube,speakers and etc...I found a site from Keen@eden.com(de-bugging a amp).I followed his instruction format.I already have a schematic from Loud Tech.I did a visual on the P.C. Board for buldging caps.bad resistors,and etc.I dont see anything on a visual base on any defects.The fuse in the amp is good! I bought this amp for the educational purpose of repairing it and when I play (low rent gigs) I want to use it for the purpose of stage drunks and or people looking for a easy rip off of equipment! I have tube amps also that Im partial to.I like too cover my bases also.Ha! I wasnt clear on dis-charging a solid state,That it is done the same way as a tube amp! Yes,It doesnt matter if I turn either the gain,master volume,or go from clean to dirty channel,The amp hisses ,no matter which knob I turn( the hiss noise gets louder).I have looked into a lot of eduacation forums,you tube tutorials and etc! on electronics.Im looking into future eduacation on a degree level.I really appreciate the input from you people.Im trying to limit and narrow down the defects of the amp.I dont have a oscilloscope,but iI do have a digital multimeter.Once again Thanks  ADV

Hello,This is first time to post!I bought a used crate 410 triode.Im having probelms with it though.The amp has a hiss in it which amplifies when I turn the volume knob up,and the hiss amplifies on every knob I turn,(The hiss sounds like a pink nose mic on which is used on a Rain E.Q.) The amp has two pre-amp tubes(ax-7 s ).I pulled the tube fatherest away from the input and the hiss became very faint,and then I pulled the tube closest to the input and the amp went dead,not even a light came on the front of the amp.I would like to repair it myself and Im a newbie in electronics.I need to know,since this is solid state with pre amp tubes,How do I dis-charge(De-Zapp) the amp? I would appreciate If an experience person could give me some pointers on repairing the amp.I would be very grateful for the input. Thanks  ADV