Ampeg BA-115 power transformer, HELP needed!

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Giacomo79

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Dec 3, 2017
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Seattle, WA
#1
Hi,
I'm trying to find a replacement part of my bass amp Ampeg Ba-115.
The original is an SLME 94-291-01
Can you help me to find the specs of this transformer?
I would like to know especially the secondary output voltage, to find a possible replacement online without spending a lot of money.
The schematic report a 100VAC 50/60Hz with a 2A thermal fuse for USA models I think, I suppose the voltage out of the secondary, should be +40 and -40 Volt I suppose, 40 VAC.
Thank a lot for your help!
 
#4
Hi Paul,
Nice to meet u!
To answer your question: there is not secondary output voltage when the primary of the transformer is powered on by the board or AC. I also replaced the thermal fuse of the transformer but the result is still the same. I also checked the amp board with the multimeter applying a voltage to the circuit with an external power supply. When the power line from the transformer is bypassed everything is fine and I have voltages coming out from speaker connection.
 
#5
The amp is a USA model and not Japanese, it worked with 120 AC volt US.
As for the service manual: The Power requirement is 100-120 VAC 50/60Hz, 50W.
I'm just trying to find:
1- the specs of the original transformer SLME 94-291-01, especially the secondary voltages.
2- The VA of this model (70 I suppose but I'm not sure)
3- I cannot find a replacement online, neither the original. I would like to try with mouser/digikey, but I need some help to find a replacement then could fit in the amp and be a good choice instead of the original.
4- I also know that some Create bass amp could share the same transformer, but I do not know which models.
 
#7
Giacomo79 said:
The amp is a USA model and not Japanese, it worked with 120 AC volt US.
As for the service manual: The Power requirement is 100-120 VAC 50/60Hz, 50W.
I'm just trying to find:
1- the specs of the original transformer SLME 94-291-01, especially the secondary voltages.
2- The VA of this model (70 I suppose but I'm not sure)
3- I cannot find a replacement online, neither the original. I would like to try with mouser/digikey, but I need some help to find a replacement then could fit in the amp and be a good choice instead of the original.
4- I also know that some Create bass amp could share the same transformer, but I do not know which models.
Click to expand...
Is there a reason that you are trying to source a replacement that is not Ampeg OEM?
I'm pretty sure the folks at Ampeg would help you either with a replacement, or the info you want.

Welcome to TB also.
BTW, if you list your location it might be helpful for folks offering advice.
 
#9
I'm trying to search for a replacement since online I don't know where to find the original. I contacted the suppliers in Seattle that are suggested by the Ampeg support webpage. They suggest me to look into another website where I didn't find the original transformer for BA-115.
 
#12
Giacomo79 said:
I'm trying to search for a replacement since online I don't know where to find the original. I contacted the suppliers in Seattle that are suggested by the Ampeg support webpage. They suggest me to look into another website where I didn't find the original transformer for BA-115.
Click to expand...
Check an outfit called Full Compass.
They carry a lot of other OEM replacement parts for other amp companies.
Don't know about Ampeg, but worth a try.

Also, another check of your transformer...
Completely disconnect all leads and check primary and secondaries for continuity.
This would tell you if a winding is open. If no open windings but no voltage at the secondaries, there may be a problem elsewhere and not with the transformer. It would be a pretty expensive proposition to buy a new transformer only to find out that wasn't the problem.
 
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#14
From what you have posted, which is full of errors, I'm going to suggest that you get some professional help from somebody familiar with this specific transformer (which is similar to a few other Ampeg transformers for amps of this style).

The factory transformer is not 100V for the USA market (they use a universal primary transformer that is differently wired than most applications), the 100V wiring is strictly for Japan, the fuse for domestic & Japan is not 2A, etc.

If you have the service manual and understand it, the data is there but you will have to do the calculations backwards to find out.
 
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#15
yeah crate BXR100 uses same transformer and mercury magnetics has a replacement CRT-BX100-P unfortunately its a 175 $ part

search shows a Kustom KXB100 amp uses same part number. think that amp is still in production.

Schematic shows 40 volt +- rail on the amplifier, with 2.5amp norm blo fuse on the AC

so what we talking here with 110/120 volts 190 to 270 ish volt amps or plain jain 250 VA.

with a 30-0-30 volt transformer id expect usual 40/44 volts after bridge depending on transformer VA
 
#16
BogeyBass said:
yeah crate BXR100 uses same transformer and mercury magnetics has a replacement CRT-BX100-P unfortunately its a 175 $ part

search shows a Kustom KXB100 amp uses same part number. think that amp is still in production.

Schematic shows 40 volt +- rail on the amplifier, with 2.5amp norm blo fuse on the AC

so what we talking here with 110/120 volts 190 to 270 ish volt amps or plain jain 250 VA.

with a 30-0-30 volt transformer id expect usual 40/44 volts after bridge depending on transformer VA
Click to expand...
Except that this is incorrect according to the Anpeg docs I have.

The OP really needs to find the correct part. Since this is a safety related part that's located across the primary supply. And because the primary winding is not standard nor typical, I will not attempt to lead the OP down a path that may put him and others in a dangerous situation.
 
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#18
This transformer will work but you MUST contact them about the correct 120V connection which is not shown. Do NOT use the 100V connection.
 
#20
As suggested, contact Ampeg customer service, ask for a power transformer primary wiring diagram for the -40 transformer to verify. Also ask what fuse you should use.
 
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