Ampeg SVT-350H Stopped Working

[Brain Inepstein]

Hi, I'm new on here so hello to everyone!

My Ampeg SVT-350H, which I bought from new about 10 years ago, has broken down. Never had a problem with it before and it is always subjected to heavy use (100 gigs + per year, every year).

I was playing in a gig on Sunday when suddenly there was no sound. I turned round to find the peak LED was on constantly. The amp was on, there was power but no sound. There were no pre-breakdown symptoms and this happened without warning.

I obviously know how to set up the input gain/master volume/peak etc as I've used this amp for years and it was only running at half volume through my Ampeg 410HE cab. I've never run it with anything other than Ampeg cabs (410HE/15E/810E).

I emailed Ampeg tech support yesterday and the only advice I got from them was "take it to an authorised Ampeg Service Centre" - great help!!!

I'd be massively grateful if anyone knows what might have happened to my amp and if it's repairable and/or if it's costly.

PLEASE HELP!!!!

[Arjank]

Is the peak LED also on when no bass is plugged in?
You also can check the fuses, one is probably on the back of the amp and maybe there are one or two inside the amp.

[MuzikMan]

Don't be too hard on Ampeg's tech support. I don't think it would be in their legal best interest to advise people to go poking around inside their equipment.

[Brain Inepstein]

Hi Arjank,
Thanks for your quick reply. Yes, peak LED is on even when jack lead is taken out. As soon as I turn on the amp the peak LED comes on and stays on. Fuse on the back is ok because it's powering up but I don't know of any other fuses???

[Arjank]

Yes, peak LED is on even when jack lead is taken out

The peak led is for the pre-amp section. Did you also try the "pad" button?

Check page 7 of the manual http://www.ampeg.com/pdf/SVT-350H.PDF

There is also a wiring diagram, the fault might be in the pre-amp gain section.

Also check this thread:
Ampeg SVT-4PRO peak light stuck on

[Brain Inepstein]

Thank you for your Help Arjank.

I will look into what you've suggested. I tried seeing if the pad in/out did anything but it didn't unfortunately. Really strange as all my settings were as per normal and there were no warning symptoms.

I'll let you know how it turns out.

In response to MuzikMan, I fully agree with you. Ampeg have to think about the risk elements (safety and legal) when offering advice to owners and could never condone DIY repairs for obvious reasons. This is not what I asked them however. I simply asked, in their educated opinion as the manufacturer, whether they could offer any suggestions on what they thought might have gone wrong being mindful that they might have come across this problem before.

Not a lot of money to them, but I've spent over £4,000 of my hard earned cash with Ampeg over the years and I don't think I'm being unreasonable to expect more than a one sentence reply from them just telling to take it to one of their authorised repairers! I had already worked that out for myself but just wanted to see what they thought before I spend out even more!!

It felt like they hadn't even read my message and just selected one of their default replies to be honest.

And I'm an extremely vocal supporter of anything Ampeg to anyone I speak to. Just felt a little short changed yesterday when reading their response.

[Jerrold Tiers]

The peak is a pretty simple circuit, which looks at a couple stages in the preamp and lights an LED if the peak level is too high.

If one of the stages has a problem and goes "DC", then the light may light all the time.

Could be any of several things.... problem with 16V power supply, problem with teh actual preamp stage, or (much less likely) a problem with peak light circuit. Even a problem with a connector, since the 16V comes from power amp on a connector and harness.

Try plugging into power amp input..... you may get sound, if so, the problem is in preamp. if not, problem could be in power supply or..... But since power amp uses the 16V supply, a problem there can look like a big problem when it really is a $4 part.

In any case, probably NOT expensive, probably an hour's tech work and low cost parts. Some small chance of a larger problem, impossible to tell for sure. The power amp check will tell more

[Brain Inepstein]

Thanks for your experienced advice Jerrold. Invaluable to speak to someone who has this knowledge. Really appreciate you taking the time to respond to my problem.

Update: I took it to a repairer who had a look, found a number of dry joints in the preamp circuitry and a few other things that were either about to go wrong or contributing to this particular problem (sorry, he did tell me but I'm no tech-head) and the amp is now working fine again. Cost was under £50. Phew!!

And an update on Ampeg: The UK distributor (LOUD Tech) replied to me yesterday. I must state here that their response was very good and very helpful. They have restored my faith in humanity (and Ampeg). Well done Ampeg, I still love you!

On reading many other posts on here over the last few days, even though my particular head is considered by many as not being a genuine Ampeg model, I will say that the 350H has always delivered for me. I've owned many amps over the years from Trace Elliots, an old HiWatt through to a lovely early '70's Fender Bassman stack - all of them valve bass amps - which I ultimately think sound better than the solid state stuff (personal taste) but if you're gigging all the time you've really got to look after them very very carefully and I went for the solid state 350H for live use purely because it could be slung in the back of the van at the end of the gig and didn't need to be treated like a new born baby... to a certain extent! I loved the look of the Ampeg stuff and didn't want that flashing light 'Close Encounters' look of some of the other solid state/rack mounted equipment on the market.

I've used it in various outfits with my 810E cab from a three piece Cream/Experience/Beck Bogert Appice type '70's rock band, through a five piece hard rock band with 2 guitarists each using 4x12 Marshalls stacks to one of my current bands where everything is mic'd up (so I only use my 410HE). Even in theatre session work for an Elvis Tribute Artiste! If EQ'd properly and hooked up to a 'real' Ampeg cab and using a decent instrument it can deliver so much oomph I've had the two 4x12 Marshall wielding guitarists asking me to turn down! Which is always nice

Ampegs are great in my opinion and for the price, the 350H has been a bargain for me and has done at least 500 gigs without stopping for breathe until now which has got to say something about the quality of what in essence is a budget product from them.

Anyway, Thanks to everyone who responded. Hope I can return the favour some time