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Ampeg B25B-- No Output! Next troubleshooting step?

#21
Tom Gallo said:
Do you feel better now that you've hammered OP a couple of times?
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Tom - since you seem to know do much about this topic, how would YOU propose to help the OP?

I would like to hear some factually accurate (and safe) advice as to how he should start identifying the cause(s), and without the benefit of the most important tool for this kind of work.

While you might see this as hammering the OP, based on my experience I'm trying to help him understand that he has a much bigger challenge ahead than he obviously realizes.

One of the greatest talents a tech can learn is knowing when to stop and get suitable assistance. IMO, the op has gone way beyond this point.
 
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#22
agedhorse said:
As far as you accusing me of being a bully, just because you don't want to hear an opinion (from somebody who taught university level classes on "structured troubleshooting") that doesn't affirm your own beliefs doesn't make the messenger a bully when its honest, accurate and factually correct.
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We all know you're a genuine expert and we all respect that. OP explained what he did and your expertise could be used to at least provide some guidance. Instead of that, you're using the opportunity to get up on your soapbox to tell us how you feel about what OP did.

There are people in this thread who are actually trying to help.
 
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#23
Tom Gallo said:
We all know you're a genuine expert and we all respect that. OP explained what he did and your expertise could be used to at least provide some guidance. Instead of that, you're using the opportunity to get up on your soapbox to tell us how you feel about what OP did.

There are people in this thread who are actually trying to help.
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Tom - the exact point I am making is that because of what he did, there's no way to provide any meaningful or helpful guidance. It's likely that something he did in his attempt to fix the amp by replacing parts and modifying things has caused new problems. Mistakes get made all the time when replacing parts like that which completely changes the diagnostic methodology. NO assumptions can be made about the state of the circuitry because of the potential for errors.

For example, troubleshooting in a production line environment is entirely different than troubleshooting a piece of gear that was known to work originally. You don't have to worry about wiring errors, incorrect parts, fundamental errors in previously functional equipment until you start changing things out.
 
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#24
Please point me to the terms I accepted that specify that posters need to have college-level troubleshooting courses under their belts. Your attitude is elitist and unhelpful regardless of what undergrad night class you taught. Again you didn't even ask about troubleshooting performed along the way nor did you call out any specific steps as problematic (please don't at this point). I'm trying to learn and keep several old amps alive at a music nonprofit where I volunteer my time. And doing so by researching, performing basic tasks, and seeking advice.

Empirically, you are, in fact, being a bully. Believe me I have two kids who do it to each other all the time. I hope you don't treat your students this way. I would never tell a motivated learner that they can't learn because they don't own an oscilloscope, and I would not return to a teacher who said that. Use your knowledge to advise and mentor, not to talk about yourself and cast negativity without anything helpful to add. Please exit this thread so I can fix our damn amp. lol.

agedhorse said:
How do you propose anybody help with no way to know what you might have done inadvertently?

The first step is to understand how the circuits are supposed to work and use a scope to verify step by step... but you don't have the most basic of tools to do this.

There are guys here who want to learn how to troubleshoot and repair amps, my comments are just as specifically stated for their benefit as anybody else. I always encourage them to learn how the individual stages work, why they are designed that way, and then how to investigate step by step each stage to verify that what they see is the same as what they expect from the circuit. This is all done BEFORE changing ANYTHING in the amp. You provided a classic example to them of what not to do, and why.

So frankly, people can pull guesses out of their collective butts in an attempt to help, but that's no better than your initial attempt and potentially more dangerous.

As far as you accusing me of being a bully, just because you don't want to hear an opinion (from somebody who taught university level classes on "structured troubleshooting") that doesn't affirm your own beliefs doesn't make the messenger a bully when its honest, accurate and factually correct.
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#25
I've received several PMs from folks following my posts who learn from the information that I provide. Some are guys who are studying to become service tech and some are guys in engineering programs who want to gain access to real world experience on these kinds of topics. This is something that I fully support and encourage, and it's rewarding to see these guys graduate and become successful in the field.

Based on something I obviously don't know about the OP, they have suggested that walk away from this thread and I am going to take their advice.
 
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#26
It isn’t bad to seek help, no matter how far down the rabbit hole you are. Talking things through helps you to look at it differently and organize complex issues in your mind. I used to talk to my dog while we were walking. Clarity would often follow.
 
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#33
beans-on-toast said:
Replacement output transformers are sold here: Output Transformer OT319/471 for Ampeg B25/B25B/V3/B22X/B42X - Product Details. They might be willing to provide the DCR's for you to test.
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Thanks for the tip, I called Fliptops and the guy was really helpful. His first question was what the resistance readings are on the OPT windings with all the leads detached from the amp and power tubes out. He wanted to know load between red center tap of the primary windings and the windings themselves. Turns out all values are infinite between red and any of the windings. Sounds like the OPT needs replacing. Sound logical to you?
 
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#35
oldsmobuick said:
Thanks for the tip, I called Fliptops and the guy was really helpful. His first question was what the resistance readings are on the OPT windings with all the leads detached from the amp and power tubes out. He wanted to know load between red center tap of the primary windings and the windings themselves. Turns out all values are infinite between red and any of the windings. Sounds like the OPT needs replacing. Sound logical to you?
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Yes, there should be a readable resistance between the red and the plate wires, blue and (often) brown of the primary.

They sell Heyboer replacement transformers. Very good quality, made in the USA.

If the output transformer is the problem, a concern is what caused it to blow. There are many possibilities. What you don’t want is to install a new one and then damage it as well. Everything needs to be checked and rechecked. Don’t forget about the power tubes, there can be a short there.
 
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#36
There’s definitely nothing readable between red:brown or red:blue. The fliptops link you sent earlier is the Heyboer? or is that elsewhere? Thanks for the assist!

beans-on-toast said:
Yes, there should be a readable resistance between the red and the plate wires, blue and (often) brown of the primary.

They sell Heyboer replacement transformers. Very good quality, made in the USA.

If the output transformer is the problem, a concern is what caused it to blow. There are many possibilities. What you don’t want is to install a new one and then damage it as well. Everything needs to be checked and rechecked. Don’t forget about the power tubes, there can be a short there.
Click to expand...
 
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#37
Hindsight is 20/20 folks. If we all did "what we were supposed to do", the world would be a much better place. There probably wouldn't be a virus having its way with most of the world right now. Put yourself in the OP's shoes and respond in a way you would like to be treated if you were in need of help. Half the battle is asking, right?

At this point, the advice should be given to the OP to have the amp fixed by a certified professional. I for one am very thankful for the help I've received through this forum. It's best to keep in mind that some of us are artist and players and simply lack the technical knowledge that many possesses.

All the education and technical know-how are useless if we can't learn how to respectfully communicate with our audience. These tech questions come up far too often and the "Amps and Cabs" section is a mishmash of gear debates, acquisitions, should I buy, and other topics outside of "Troubleshooting".

We could make this forum a better place by asking the mods to create a troubleshooting section for amps with plenty of stickies on 'do's and don'ts'.
 
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#39
That’s great, thanks. I feel good about buying from them as they were pretty helpful on the phone. I’ll report back when I get it installed. I’ll double check everything in circuit and use the dim bulb tester as I have been after every change. Thanks guys!

beans-on-toast said:
Fliptops sells only Heyboer transformers for Ampeg replacements, so the one in the link was from them. The link indicates that the B25B replacement is made by Heyboer.
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#40
Raw N Low said:
Hindsight is 20/20 folks. If we all did "what we were supposed to do", the world would be a much better place. There probably wouldn't be a virus having its way with most of the world right now. Put yourself in the OP's shoes and respond in a way you would like to be treated if you were in need of help. Half the battle is asking, right?

At this point, the advice should be given to the OP to have the amp fixed by a certified professional. I for one am very thankful for the help I've received through this forum. It's best to keep in mind that some of us are artist and players and simply lack the technical knowledge that many possesses.

All the education and technical know-how are useless if we can't learn how to respectfully communicate with our audience. These tech questions come up far too often and the "Amps and Cabs" section is a mishmash of gear debates, acquisitions, should I buy, and other topics outside of "Troubleshooting".

We could make this forum a better place by asking the mods to create a troubleshooting section for amps with plenty of stickies on 'do's and don'ts'.
Click to expand...

Very well said.
Falls under the "not what you said but how you said it" category.

Here's some advice I was given that I try to remember.
Does it need to be said?
Does it need to be said now?
Does it need to be said by me?
 
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