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Ampeg BA600 power amp issue

Sparkl

Sparkl

Apr 23, 2011
1,710
1,443
Europe
#1
Hello folks!

I have stumbled upon this nice little combo and upon plugging it in I realised that there was no sound coming out of the amp. I tried isolating the preamp (via headphones) and it works, so my conclusion is that it must be the power amp. The amp has been sent into numerous repair offices but to no success. I just got the amp back under the explanation that the technician couldn't figure out the cause and fix it.

So now after a year of repairs it sits in my room again.

It is obvious that I might probably need to replace the whole power amp module. Problem is I don't know where to get one. If I type the power amps serial or model number google gets nothing.

I already wrote to Ampeg and only got a response that I should contact my local Ampeg dealer in Europe. I called a couple of stores and they couldn't help me out, each one of them referring me back to the Ampeg tech support.

If this power amp is no longer obtainable, is there a viable alternative to swap it with?

Here are some photos I took just now for you guys to see. The only thing that is obvious to me is the burnt molex.

What else happened with the amp and under what conditions is unknown to me since I am not the original owner but since I got it for free, I might as well try to fix it. :)

Looks like a nice and powerful combo.

Thanks in advance!
 

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#4
That's Ampeg's proprietary parts, something that I think you will probably have a difficult time finding service unless you have access to a VERY qualified and knowledgeable service tech. The average tech is going to struggle, and parts may not be available. You will need to have them contact the manufacturer for availability. There are several different boards involved, any one (or all) might be at fault. There's the SMPS, the class D power amp and what looks like a small switching regulator board for control voltages.

After being ridiculed by a couple of "experts" on TB for "foolishly" choosing ICEPower as a power supply/power amp module in the past, I mentioned that there is a distinct advantage to using a module manufactured by a LARGE off the shelf specialty supplier who supplies multiple manufacturers in the MI, pro audio and consumer audio industries. These IcePower modules are not proprietary to any single amp manufacturer (other than IcePower itself) but are spread across multiple industries, so when replacement parts are needed there are more options for a service center to choose from. This is a good example IMO of the benefits of such a multiple use part. I still stock in large quantities (and have access from multiple sources) IcePower modules going all the way back to the beginning (almost 20 years ago). The same may not be true of sole source sole use parts.
 
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#5
It’s unfortunate that you can’t find anyone to fix your amp. There’s plenty that a tech can investigate. The schematics are available, they have reference voltages for checking out the amp. A tech can trace a signal through the amp, from the pre through the power amp. The amp is repairable, you just need to find the right tech.

Start by patching an instrument cable between the effect send and receive. See if that helps.

Next, if you have a regular two button foot pedal with a TRS plug, try it in the footpedal jack. One button is a mute, the other selects the amp voicing. There may be a problem with the mute circuit. If you don’t have a pedal, try quickly cycling a ¼” plug in and out of the footswitch jack a dozzen or so times. If there is oxidation on the jack shunt contacts, this can sometimes clean them a bit.

If anything improves, have a tech clean the jack shunts with deoxit.
 
#6
beans-on-toast said:
It’s unfortunate that you can’t find anyone to fix your amp. There’s plenty that a tech can investigate. The schematics are available, they have reference voltages for checking out the amp. A tech can trace a signal through the amp, from the pre through the power amp. The amp is repairable, you just need to find the right tech.

Start by patching an instrument cable between the effect send and receive. See if that helps.

Next, if you have a regular two button foot pedal with a TRS plug, try it in the footpedal jack. One button is a mute, the other selects the amp voicing. There may be a problem with the mute circuit. If you don’t have a pedal, try quickly cycling a ¼” plug in and out of the footswitch jack a dozzen or so times. If there is oxidation on the jack shunt contacts, this can sometimes clean them a bit.

If anything improves, have a tech clean the jack shunts with deoxit.
Click to expand...

Educated guess, but there's probably more to this problem.
 
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#17
beans-on-toast said:
The european supplier doesn't have any, search here: Your favorite place for ordering Mackie and Ampeg spare parts.

Did you try what I suggested with the footpedal jack?
Click to expand...

Invalid Link Removed

Based on this, they only have a replacement driver and some casters :P

I did an extensive search on this before already and couldn't find a thing on the internet. I will write them an email just in case, thanks!

Forgot about the footswitch thing, will try! I tried the FX loop and it didn't make a difference but as the others say, I don't think that this is an issue when I actually have a burnt molex. Doesn't hurt to try though!
 
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#18
Sparkl said:
Ok so I wrote to Thomann and they might be able to get the module I am seeking. Hopefully this fixes it for good. :)
Click to expand...

How do you know what part or module is in fact bad? There's a lot going on between modules on your amp, without properly troubleshooting this you might very well end up with a destroyed new module. Most parts suppliers will not warranty parts sold to non-authorized service centers and individuals.
 
#19
The molex connector burned up for a reason. So yes you could literally replace the whole board n torch the thing again.

It does have safety features so youd assume it shut down before you see a torched molex.

Could be very very lucky. And that molex and crimp connections were poopy. And it was arching like hell. So few new wires and clean up you could have working amp. I doubt it. But yah never know. I've seen countless arching molex connections on crossover modules on pegs. Maybe the guy that's been making crappy crimps at Ampeg finally retired...lol.

A good tech can actually repair a board not shot gun the whole thing

Not saying bad on your part. Just few basic tests make sure you don't loose out. Or go through hell buying something you don't need.

Could pull board see if any traces lifted or heat damage. If not could be simple bad connection and only arching.
 
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#20
The burned connector is almost certainly the result of the fault, not the cause of the fault.

There may be a power supply problem as well as an amplifier problem, and often there are interlocks between the amp and the power supply that can enable or disable parts of the supply in the event of a fault. All of this is much more complicated than an internet wild ass guess can solve. A qualified tech experienced with this model or line of amps is your best bet, but if the damage involves both the power supply and the power amp, it's likely that you can find a used one for less than (or close to) the cost of repair.
 

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