Hi all , I have an Ampeg ba 108 that will power on but i cannot get any sound from the amp unless the amp is at 9 or 10 setting and even then it volume level sounds like it is set at 1 or 2 , guitar volume is on full.. Any suggestions . Also is there a fuse i should check , because i cannot find one on this amp.
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Ampeg ba 108 problems
- Thread starter CyberMan
- Start date
- Feb 12, 2006
- 60,963
- 5
- 220,655
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
It's not a fuse.
Have you tried a different bass?
Is there an effect loop ?
Have you tried a different bass?
Is there an effect loop ?
According to the block diagram in the manual the combo doesn't have an effect loop.
Maybe the -15dB pad is switched on.
Maybe the -15dB pad is switched on.
- Feb 12, 2006
- 60,963
- 5
- 220,655
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
I would certainly check for the pad switch being accidentally turned on. If it's not that, there's nothing user serviceable, additional diagnostics are necessary to CORRECTLY identify the cause of the problem so that the problem can be CORRECTLY repaired.
Hi , thanks for the reply's. Yes it does have an effects loop. But i unplugged it and tried it unplugged with no success. As for the volume pot , I tried a multi meter on it and it seems to cycle up and down ok. I don't have another bass guitar to try. Called a tech and he guessed at about a 100 dollars to fix it. They are only 135 plus tax new. It looks like new and i hate to throw it away. How could i test it to see if the -15 is not engaged.
- Feb 12, 2006
- 60,963
- 5
- 220,655
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
The -15d switch is a little black switch next to the instrument input jack. Press to engage/disengage. If it is the OUT position it is not engaged.
There'so no effects loop, but there is an AUX input.
I use one as my practice amp, it's a lovely little combo for bedroom practice.
There'so no effects loop, but there is an AUX input.
I use one as my practice amp, it's a lovely little combo for bedroom practice.
Do you get get good volume with something plugged into the aux input (CD/MP3 player, computer, etc)?
Try to play your bass through an effect pedal with a preamp (such as a sansamp or other, if you have one), plugged into the effects return (bypass the preamp section).
Try to play your bass through an effect pedal with a preamp (such as a sansamp or other, if you have one), plugged into the effects return (bypass the preamp section).
The BA-108 doesn't have an effects loop, this is a low cost amp. Even the BA-110 doesn't have one, and neither shares a preamp board with the more expensive BA series combos that do.
I'd remove the chassis and do a visual inspection after ruling out external components like the bass and cable. You be looking for obvious signs of burnt components or board. Assuming it's a V3, the preamp board is perpendicular to the faceplate. This will make visual inspection easy without removing the board. But it is also largely populated with surface mount components. A magnifying glass will be helpful, but not necessary.
I'd remove the chassis and do a visual inspection after ruling out external components like the bass and cable. You be looking for obvious signs of burnt components or board. Assuming it's a V3, the preamp board is perpendicular to the faceplate. This will make visual inspection easy without removing the board. But it is also largely populated with surface mount components. A magnifying glass will be helpful, but not necessary.
- Feb 12, 2006
- 60,963
- 5
- 220,655
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
Note that in probably 99% of the time, there will be no visually burned or obviously failed parts.
I am amazed that folks who know little to nothing about electronics assume that they can repair electronics by "replacing a couple of parts" without understanding what the parts actually do.
I am amazed that folks who know little to nothing about electronics assume that they can repair electronics by "replacing a couple of parts" without understanding what the parts actually do.
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My apologies as I missed OP's post where he stated the version. This is even easier to troubleshoot. As others suggest, take your line out and put that into your stereo amp or something. See if you are getting a proper signal there. Yes, it's not the preamp section but the return jack or power amp section, or no then it is the preamp.
A multimeter, low-end oscilloscope, basic function generator for a sine wave, and maybe a varian is all he'll need. Ampeg has the schematic online and it's rather basic amp circuit. Unfortunately, Ampeg's schematic that's online doesn't document the test points, but it should be hard to figure out.
Oh, and a steady hand plus good testing procedures so more damage is not create. This amp doesn't have high voltages. It won't exceed the telephone line voltage on the DC side, and of course, the wall outlet on the AC side.
- Feb 12, 2006
- 60,963
- 5
- 220,655
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
The AC primary is in fact defined by all safety standards as a hazardous (ES3) voltage. Proper safety precautions are required.
Yeah, a multimeter, scope and generator are necessary, but understanding how the circuit is supposed to work is kind of necessary to use those tools. The tools do not provide the knowledge, just like owning a scalpel makes you qualified to do surgery.
Yeah, a multimeter, scope and generator are necessary, but understanding how the circuit is supposed to work is kind of necessary to use those tools. The tools do not provide the knowledge, just like owning a scalpel makes you qualified to do surgery.
Tip to preserve your speaker:
Even if the sound coming out is very low, DO NOT turn the volume knob past the halfway point so you can hear something. If whatever is causing the low sound happens to clear itself it will come on at that high volume possibly killing your speaker.
Hi all, it did indeed turn out to be a bad volume pot. I did a swap of pots between the volume and the CD pot and to my surprise it works fine . Not worried about the CD pot as i would not use it much anyway . Thanks for everyone who replyed . And thank you filmtex for your suggestion , i figured that was a good place to start.
I'd still replace the CD pot. They're not expensive, and even if you only use it once in the next couple years, you're going to be annoyed that it doesn't work
