Circuit diagram for #4 JIM ROOT

[bluesman8]

Hi, Just out of warranty our bands guitarist's lovely amp has packed up. I see that Orange have a policy of not suppling circuits to owners. We live in a very remote area of Europe with no service agent.......I am the roadie and a qualified electronics engineer (retired) and quite capable of repairing our unit. I would rather not spend time reverse engineering the device as we have gigs to do, can anyone point me in the right direction to get a circuit in a hurry please so I can get the damn thing fixed and the band back performing?
TonyE

[Jondog]

Haven't seen any yet of that amp floating around. Apparently it has the same dirty channel preamp as the Rockerverb and I'd assume it uses the same effects loop and power section as the Dark Terror. Pretty sure the Dark Terror is the same preamp as well, just a different tone stack.
Rockerverb preamp schematic: http://www.orangefieldguide.com/OFG_SCH ... sheet1.jpg

Dark Terrror schematic: http://guitar-gear.ru/forum/index.php?a ... h_id=22573

[bluesman8]

Jondog, my thanks am looking at it now.
TonyE

[Jondog]

Jondog, my thanks am looking at it now.
TonyE

What exactly happened to the amp?

[bluesman8]

Jondog I have retrieved the preamp, cct many thanks, the second link is giving a

Unable to connect
Firefox can't establish a connection to the server at guitar-gear.ru.

Do you have an alternative link....the fuses are ok but the amp is dead, want to 'scope the power supply internals..
TonyE

[bluesman8]

Aha, my MALWAREBYTES program is blocking the site as a
known danger...

[bluesman8]

Ok, disabled the blocking of the IP address for a few seconds and retrieved the cct without any ill effects. Will take the thing apart tomorrow...if this cracks it the beers are on me ....
TonyE

[Jondog]

[Jondog]

Tubes are OK?

[bluesman8]

Jondog...that is the cct, many thanks
TonyE

[bclaire]

Are you POSITIVE that the fuses are OK? I would swap them out anyway as I've noticed that a lot of blown fuses these days look OK but have blown despite the way they look....

[bluesman8]

Cracked it and back in business again making lots of musical noise...due entirely to your assistance with the circuit and related comments.........FYI yes it was a fuse, the one integral to the mains socket on the back of the unit rated at 500ma.
Never trust a lead guitarist that tells you he has checked all the fuses, he did not know that one was there !

A question. I have had the amp on soak test for 2 hours and no problems. Is this fuse a little under rated at 500ma? Will it go again and should I up-rate it to 750ma just be sure? The 3amp in the mains plug will take care of anything really serious enough to try and start a fire lol
TonyE

[Jondog]

I'd stick with 500 mA. It could of blown because of a power tube on it's way out, which may not be as evident when the amp is not being played through. Make sure one or both of the tubes aren't red plating.

[bluesman8]

Thank you, will run a current check on the output stage. Once again guys, magnificent response, have one on me !
best regards (till next time)
Bluesman

[timNZ]

So does anyone actually have the #4 JR schematic? Or know the component differences between it and the OR15 for sure? Basically I'm looking for an OR15 in a Terror box, and from what I've read maybe I can get that by changing a resistor and a couple of caps in the tone stack of the JR.
cheers, Tim