OR120 Help

buxtonsarethieves · Post by **buxtonsarethieves** » Thu Jul 31, 2008 9:43 pm

Hey everybody, this is my first post as today I acquired an Orange OR120 either from 74 or 75 with a master volume mod. Now unfortunately this post is not on such a happy note. I won this amp on ebay, and when it came to my door today I was super excited. I was informed that this amp was in excellent working condition and had just been retubed and biased.
So I plugged it in (16 ohms into a 16 ohm cab) and fiddled around for a bit. Then I decided to crank it, I turned everything up all the way, and right after I turned up the master volume the sound started getting quieter and quieter until....nothing. Which is what I'm left with right now, an amp that I just dropped a ton of money on which does nothing except hum slightly (not through the cab, the actual head is humming).
Any advice people could offer would help me out a great deal, I'm feeling pretty bummed right now. I emailed the guy I bought it from but have yet to hear back.
Thanks in advance.

chrismathewsjr · Post by **chrismathewsjr** » Thu Jul 31, 2008 10:32 pm

Transformers physically humming are not too uncommon, but they are usually pretty quiet - how loud does the head itself hum?

Assuming the amp was ACTUALLY retubed and biased and in working condition, it's possible the power tubes have failed early.

First thing I would do is take it to a tech and have him give it a good good look over. See if there are any original caps in there that need to replaced (most likely filter caps, if they haven't) and for any other repairs/mods that have been done to it.

When I bought my '74 OR120, it had some crazy modified bias circuit that was drifting and took out a few quads of mine before I realized I needed to change it back to stock.

buxtonsarethieves · Post by **buxtonsarethieves** » Thu Jul 31, 2008 10:40 pm

Thank you for the response!
Ok so here is an update, the HT fuse had apparently blown, so I went to radio shack and picked up some new ones. Put one in. YAY!! Cranked it. SWEEET! And then it did the same thing again. Including the one that came with the head I have now blown 3 HT fuses. Anybody have an idea what that means?

Simon Wicks · Post by **Simon Wicks** » Thu Jul 31, 2008 11:11 pm

Yeah, likely the power tubes got knocked during transit and they just shorted out. Dont replace the fuse too much otherwise you may cause serious damage to the amp. New tubes, and new bias time i'm afraid but all should be well after that!

buxtonsarethieves · Post by **buxtonsarethieves** » Thu Jul 31, 2008 11:33 pm

The tubes were taken out of their sockets during shipping and seemed to be packaged well, but this seems to almost certainly be the issue as I did not blow any fuses when I removed the power tubes.
Well looks like its time to scrounge up some money for new tubes and a bias. Can I have just anybody who knows stuff about amps do this? I don't know that there are a lot of people around here (south jersey) too familiar with oranges.

Ryan Rapp · Post by **Ryan Rapp** » Fri Aug 01, 2008 5:26 am

hey there. is your problem only at high power (playing very loud)? i had a similar issue with an 100w JMP i have. turns out - at high volume and power, there was a small arc of current in the power section which would pop the fuse every time i cranked it up.

i know a good tech in NY. i don't know how SOUTH you are in Jersey. but he is worth the trip or ship. I buy all my amps broken down or beat up and have him bring them up to speed. Great price too. he fixed up my OR120. thing was destroyed - totally didn't work at all. he had it all fixed up - new ohm selector, new tube sockets, half power switch, standby switch, new caps, couple of other minor things - including all new tubes. all for under 400 bucks. which is damn good. sound like you have considerably less problems. let me know if you want his info.

buxtonsarethieves · Post by **buxtonsarethieves** » Fri Aug 01, 2008 6:05 am

From what I have tried out, the amp seemed to work fine when messing around at lower volumes, but as soon as I turn up loud the fuses blow. It does sound like your problem with the JMP. Is that a cheap fix?

As far as where I live, I am actually 15 minutes outside of Philadelphia. My last amp I never had a problem with and had a fixed bias so I don't really know anyone around my area who does this sort of thing (esp with Oranges). I don't really know that I'd want to ship this thing out, it seems like kind of a hassle and I don't know if I have that kind of money right now.

I'm hoping its just a matter of new power tubes. Would that also explain the cranking=blown fuse while being able to play fine at low volumes? It would be a real pain to keep dishing out money for something I already paid a lot for and was told was in excellent working condition.

Is your tech in or around New York City? I have a friend who goes up there to see his g/f all the time maybe I can just stick it with him heh.

Simon Wicks · Post by **Simon Wicks** » Fri Aug 01, 2008 8:21 pm

It should just be power tubes but arcing can never be ruled out. If thats the case it will fry your power tubes again and throw the HT fuse. Easily enough fixed by replacing the socket.

Any valve amp tech should be able to bias the amp. Its not hard to do but the amps can be a bit of a funny one as the circuitry is somewhat different to normal Fender type amps. Its not hard to figure out though once you have the schematic in hand.

buxtonsarethieves · Post by **buxtonsarethieves** » Thu Aug 07, 2008 10:04 pm

Ok, so update. I took it to a local amp tech yesterday and he said I'd have it back today. Well I just got it back and after dropping over 400 dollars (he said it needed new tubes, the power tube sockets modified to prevent arcing, and the bias circuit needed a serious rebuild) the thing is still blowing fuses, faster now than ever actually. I can't even flip the power switch now without blowing them.

I'm taking it back to him tomorrow, I'm assuming the rest of the work will be free (considering he really didn't *fix* anything). Even so I'm seriously about to try and cut my losses and sell this thing off for as much as I can get. Even before the fuses blow, I couldn't really get into the tone of this thing anyway, it was really, REALLY "farty", I'm not sure if this is how it's supposed to sound... And for as loud as this thing is supposed to be, with it totally dimed it's really not that loud at all...

Ugh I'm just so frustrated already having dumped 2 grand into this amp and it's given me nothing but grief.

chrismathewsjr · Post by **chrismathewsjr** » Thu Aug 07, 2008 10:38 pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by buxtonsarethieves
 Ok, so update. I took it to a local amp tech yesterday and he said I'd have it back today. Well I just got it back and after dropping over 400 dollars (he said it needed new tubes, the power tube sockets modified to prevent arcing, and the bias circuit needed a serious rebuild) the thing is still blowing fuses, faster now than ever actually. I can't even flip the power switch now without blowing them.

I'm taking it back to him tomorrow, I'm assuming the rest of the work will be free (considering he really didn't *fix* anything). Even so I'm seriously about to try and cut my losses and sell this thing off for as much as I can get. Even before the fuses blow, I couldn't really get into the tone of this thing anyway, it was really, REALLY "farty", I'm not sure if this is how it's supposed to sound... And for as loud as this thing is supposed to be, with it totally dimed it's really not that loud at all...

Ugh I'm just so frustrated already having dumped 2 grand into this amp and it's given me nothing but grief.
<hr height="1" noshade id="quote"></blockquote id="quote">

That's a bummer, looks like the tech must not have tested it out very much. Is he a trusted tech in the area?

Don't give up just yet, you're holding onto a pretty tasty amp when it works.

buxtonsarethieves · Post by **buxtonsarethieves** » Thu Aug 07, 2008 11:15 pm

I had him recommended to me by two friends, although now I'm finding out the one had one bad experience with him (why he didn't tell me that in the first place I don't know, I think he just forgets things haha) and apparently so have a few other people.

So I guess he gets one more shot to fix it (for free) then I'm gettin my money back.

Gladmarr · Post by **Gladmarr** » Thu Aug 07, 2008 11:29 pm

Sounds like you got screwed by a hack amp tech. If he rebuilt your bias circuit, he might have messed it up trying to make a Marshall bias circuit out of it. I'd get my money back from that tech for sure and take it someplace better. Good luck, man.

Damn-Deal-Done · Post by **Damn-Deal-Done** » Fri Aug 08, 2008 1:24 am

A rule of advice. Make sure you lay the rules down to amps techs before handing over your amp. Always ask to keep the replaced/faulty parts and get details of the work done. If you can take a photo at home of the amp inside and out so you can confirm they have done work. I've been taken once by a so called reputable amp tech, don't take their s---.

I had a SWR bass amp mended a while back, this guy had the amp for months, cost me about Ã‚Â£60. He fixed the amp and said there was some strange things going on with the circuit that he "corrected", this was after he'd fixed it. Maybe SWR intended those strange things. I got the amp home and played it for about a minute before I accidentally ripped out the jack and broke the socket.

I took the amps back to have all the sockets replaced with new metal ones. He replaced only one. Then said he noticed other things wrong with the circuit which he just fixed without asking, this cost me another Ã‚Â£50, and he never did what I asked. I had my suspicion that all that was originally wrong with it was one component had burnt out, when open you could see the component that was faulty.

Before this fiasco, I asked him if he modded pedals to true-bypass. Told him I had a vintage pedal which needed doing. He argued with me that it was already true-bypass. He was wrong.

Moral of the story, never trust anyone, ever.

buxtonsarethieves · Post by **buxtonsarethieves** » Fri Aug 08, 2008 10:34 pm

Hey, I have another update but first I just want to thank everybody for all your help and input, you guys are awesome!

After a fight with my tech we settled on him getting one more shot to fix it (he says he thinks the problem was arcing, which perturbed me a little since it seemed to be a fairly obvious front-runner from the people on here, and something I thought he should have checked from the start) and if it still doesn't work, I get a full refund both parts and labor.

I did take pictures as per suggestion of the inside of the amp ,but not until after I got it back. Do you think just by looking at these pictures you guys could tell if anything looks fishy or not right? I really don't know too much about all of that stuff, and it could be a big help.

Post by **bclaire** » Fri Aug 08, 2008 10:48 pm

I've heard plenty of horror stories about amp techs that think an Orange is just a colorful Marshall and start replacing stuff, screwing up the amp in the process.

I'd get it back from him- find a REAL tech- and have them go through it and fix what has been messed with. If the current tech replaced any parts, tell him you want the old parts. Then tell him you want the money back if the new guy finds it was hacked...

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