Amp Gurus HELP!

So I have a Reinhardt 18 combo. All of the sudden the amp has no gain. I changed all of the tubes, and there was no change. I took it to a tech in town, and they said that there was definitely something wrong, but they can't find a problem. This thing used to push cranked Superlead territory. Now it sounds almost like a Deluxe Reverb. It's loud, theres no issue with volume. It's just that it doesn't have any crunch at all.

Thoughts? I can't really afford to ship this thing back to Reinhardt, and don't want to spend a boatload on repairs to not fix it

When you said you changed all the tubes did you use the same kind of tubes and have it rebiased? Different power tubes have different gain, and that manufacturer uses several different brands of tubes to get their tone. Its basically a Marshall 18w with some mods. A tech should be able to use that schematic to find his way around. There can also be a voltage loss due to a cap or a bad solder joint. I wouldnt rule out a bad guitar cord either. If someone used the cord as a speaker cord it can melt the sord inside and increase its capacitence. It may also be a guitar issue, but since you said it was all of a sudden you have to check all those simpler things first. Then you would signal trace the circuit and see where its loosing gain of not stepping up in gain properly. If the tech didnt find the problem, find a better tech. Theres always an answer, you just need someone competent enough to find it.

I have an old bassman blackface that lost its power in the bass channel. The bass channel was actually louder than the normal channel years previous. I finally got around troubbleshoothing it when I was doing a refurb replacing power caps. I found a bad cap in the tone circuit that was sucking the volume down. i also found a cracked solder joint that would make that channel crackle. A combo is subject to alot of vibration. You just have to be a good tech to find some things. Have you asked the manufacturer? maybe thay have some common things the techs come across.

The tubes are the same spec. Also I've tried different cables and different guitars. Even with a high output Seymour Duncan JB equipped guitar I have to utterly crank the amp and dig in hard to get any gain. The only guess I have is the caps like you were saying. The weird thing is it lost no volume, it just refuses to breakup now:mad:

Also talked to Reinhardt. He said this one is not done like the current 18s so he wants me to send it back. I can't really afford to do that, so I would like to find someone local or do it myself. I just don't know where to start

Have you worked with this tech before? Are you certain they are good? Took me a long time to find a shop I trusted for amp service.

I'd try taking it to another shop for a second opinion.

Thats it. If something fails completely you can usually find the problem fairly easily. From your discription it sounds like a voltage drop thats causing less gain staging. Troubbleshooting involves injecting a signal into the front end and testing the results step by step with an oscilloscope, meter and or audio probe. You have to know the technology to know whent the gain stages are supposed to be and judge what you get to know if its within tollerance. If its off too much then you have to use some math to know if the parts that support the tubes amp stages are feeding the right voltages, then if the things hot rodded like yours you have all kinds of variations that push tollerances of those components. When you push tollerances parts can fail. You can have an open resistoror cap and its just not feeding the right signal.

If you had a schematic with the voltages marked out you might be able to localize the problem but that still takes some major understanding of electronics. Its not something someones going to be able to walk you through over the internet. Its dangerous and it requires trusting someone to take proper readings with test tools. I did tech support for techs for years and even then it was a tough thing to do on the phone. The person on the other end of the line may be a tech but doesnt spend all day analizing circuits to tie it all together.

I would have them use the meter and make specific tests and help them localize the problem based on the results. I was however an extert who taoght those circuits and knew them blindfolded and the tech at least know how to test voltages.

Unfortunately thats it in a nutshell. Most tube amps are a simple design used over and over by different companies and pretty simple to those trained in electronics. They are rocket science to those with no experience. It takes at least 6 months in formal classed to to begin understanding enough to grasp how amp variationa work. Then it can take years to understand all the possible variations from a symptom.

A symptom can have thousands of causes. Experience with different amp types narrows down those possibilities to a handful, but that handful still takes an experienced tech to find the cause. I didnt really begin to understand all that till I had my diploma and started repairing music equipment full time for a year. Even then I left that business before I became a world class tech because there wasnt enough money in it to earn a decent paycheck. People, especially in music just dont have alot of cash and want things fixed for free and that doesnt put food on a techs table. You got to find someone who knows their shi(t) and can do a quality repair that wont fail again. They should also be able to tell you why the fault occured. It may be a crappy build, faulty design, cheap components, abuse by the user, or an act of god. Thats the bottom line. dork around there and make a mistake and you can do more dammage then good.

Try to switch off and restart .!!!

Been there done that^^

I have a different tech that I trust more, but he's backed up 6 weeks

I know that sucks, but perhaps it's a good sign. Good service is worth waiting and paying for IMO.