Why not put another of the same type back in to get it going. The only way to increase the current, is to replace the copper, in the transformer/inductor with the correct area for conduction. The iron/ferrite is probably OK.
As "safe play" a 15-0-15 transformer will give you around +/-22Vdc in idle mode dropping to +/-20-21Vdc in use. The advantage of such a traditional transformer is that the simple design rarely fail. In countries where transformers are produced, they can be bought at very attractive prices. Here, the transformers are as such not expensive but shipping costs are high due to the weight.
You will need a 4-5 Amp capacity thus a 120VA-150VA transformer.
Listen first to the ideas about recovering the existing SMPS. Then, make your choice. If you had the schematic of the "old" SMPS I would consider reworking that one. Without a schematic, I fear it can be quite some work.
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The smps transformer isn’t damage, it was the same one that worked it. I’ve only changed the components that was driving the transformer. The specs on the transformer have the capability to give more, I simple just don’t know how to drive it harder.
Why you all can’t understand what I’m saying.
I know it’s a complex circuitry and I have limited knowledge but you guys keep saying I can’t get more and I need bigger transformer, it’s the same one that use to work and produce sufficient amperage for the outputs.
All I want is just some simple diy builds of different types of components driving a switching transformer built in-chip or external mosfet/regulator. Simple.
I believe Formas is right in that probably the old SMPS circuit was sufficient. Thus, that the SMPS transformer should be able to give the necessary output power as is. For some reason the primary switching circuit stopped working but that could be due to poor component quality.
Formas' request for more power relates to his attempt to use a TNY268 as primary switching circuit. The TNY268 IC did not drive the SMPS transformer in a way to deliver its maximum power (it was a gamble with the TNY268).
If we can find a primary switching circuit that drives the SMPS transformer as in the old circuit, it may work well.
But, that is not going to be straight forward.
We cannot just replace the old broken components as they are Asian rare. We will need to know the old SMPS circuit in order to know the original topology and in order to adapt component values. We can most likely find components to replace the old primary switching circuit if we know the topology. Finding the optimum switching frequency (and phasing of the windings) for the SMPS transformer is more difficult but depends on the topology as well.
Formas, are you willing to draw-up the old SMPS circuit from the PCB layout and the components mounted there (reverse engineering)? We will need that to find the right replacement switching circuit.
If not, replace the old SMPS circuit with a new power supply.
Formas' request for more power relates to his attempt to use a TNY268 as primary switching circuit. The TNY268 IC did not drive the SMPS transformer in a way to deliver its maximum power (it was a gamble with the TNY268).
If we can find a primary switching circuit that drives the SMPS transformer as in the old circuit, it may work well.
But, that is not going to be straight forward.
We cannot just replace the old broken components as they are Asian rare. We will need to know the old SMPS circuit in order to know the original topology and in order to adapt component values. We can most likely find components to replace the old primary switching circuit if we know the topology. Finding the optimum switching frequency (and phasing of the windings) for the SMPS transformer is more difficult but depends on the topology as well.
Formas, are you willing to draw-up the old SMPS circuit from the PCB layout and the components mounted there (reverse engineering)? We will need that to find the right replacement switching circuit.
If not, replace the old SMPS circuit with a new power supply.
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If that is required to get to rectify the problem at hand I’ll see how best I can get it done, I work for a store that sell a lot of these boxes and my observations is that mostly have power supply problems, and parts for them is not fully available especially the PWM IC probably the mosfet/regulator can be easier to substitute.
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For my friend's Polk subwoofer, I took the easier, more reliable and sensible way to fix it.
Apparently, these SMPS subs are crap, there are loads of complaints about them.
SO.......
OUT with the BAD (smps)......... and IN with the GOOD (pwr trans).
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He's not asking for more power than original.
The original driver blew. His homebrew driver is not doing the job. Likely a properly engineered driver would work with the original coils.
(But there is a chance the original coils were marginal and that's why the original driver blew, and the homebrew driver isn't doing the job.)
I’ve tested a fully functional one and the rail voltages are 13.6vdc+/-, can a 12-0-12 transformer at 3amp do the job?
Or give me your best calculations while keeping it affordable.
Hi Formas,
12-0-12 rectified gives you around 2x16Vdc idle rectified and some 2x15Vdc in operation. That is fine for TDA2030. You will have some 16W in 4 Ohm which requires some 25W per channel from the supply. With three channels, that means some 75W for the whole amplifier.
2x12Vac and 3A is 72W(VA) without taking any music crest-factor into account. 12-0-12 3A is a good choice. 10000uF(25V) on each of the two rails.
In one of your last postings you gave us another important information, that it is professional repair you do. That means, your customers must be able to rely on you providing a functionally reliable solution to their problem with an unreliable initial design. A traditional transformer supply is probably the most reliable replacement you can find.
Replacement of the defect old components with the same but new items will most likely leave the same instability as before. Replacing the old driver components with new and better ones is a lot of work and difficult to make guaranteed reliable. I would go for safe-play with a transformer if you can get it into the box.
12-0-12 rectified gives you around 2x16Vdc idle rectified and some 2x15Vdc in operation. That is fine for TDA2030. You will have some 16W in 4 Ohm which requires some 25W per channel from the supply. With three channels, that means some 75W for the whole amplifier.
2x12Vac and 3A is 72W(VA) without taking any music crest-factor into account. 12-0-12 3A is a good choice. 10000uF(25V) on each of the two rails.
In one of your last postings you gave us another important information, that it is professional repair you do. That means, your customers must be able to rely on you providing a functionally reliable solution to their problem with an unreliable initial design. A traditional transformer supply is probably the most reliable replacement you can find.
Replacement of the defect old components with the same but new items will most likely leave the same instability as before. Replacing the old driver components with new and better ones is a lot of work and difficult to make guaranteed reliable. I would go for safe-play with a transformer if you can get it into the box.
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I have to admit I share the same view. Back when I was still a youth, I was a staunch believer of switched mode power supplies, now I avoid them like the plague. Yes, they are power efficient, but they are complicated, and necessarily use a high switching frequency, putting undue stress on components. Switching stress with its unwelcome high voltage transients and ringing, stresses components lowering their life.
I am not at all against SMPS. Today, you will need very good arguments to give your boss if you use anything but an SMPS in an electronic product. They are compact, they are leight-weight (important for transport), they normally have voltage regulation integrated in the design, they are efficient etc. The problem with SMPS is that they need to be designed by people who know them well in detail. SMPS have to be produced with the same components as recommended by the skilled designer. As supported by "edbarx", the components in an SMPS are importantly stressed and you cannot just use another cheaper component in production without risk of hampering the overall reliability. My personal impression is that is what sometimes go wrong with Asian SMPS.
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By including my username in your reply, you are putting words in my mouth which I never said or intend to say in the future. Could you please, explain to readers, why you felt the specific need to include my username in your reply? Your reply gives the impression I am one who blatantly modifies switching power supplies expecting the impossible. This is a subtle form of mudslinging and is actually of form of personal attack.FauxFrench said:
I never ever modified an existing switching power supply. I don't even attempt to repair a failed one.
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Mr edbarx,
I refer to your posting stating: "......but they are complicated, and necessarily use a high switching frequency, putting undue stress on components. Switching stress with its unwelcome high voltage transients and ringing, stresses components lowering their life."
The reference to your username was in my sentence(s): "As supported by "edbarx", the components in an SMPS are importantly stressed and you cannot just use another cheaper component in production without risk of hampering the overall reliability [no reference to you but to certain Asian production]. My personal impression is that is what sometimes go wrong with Asian SMPS."
I fail to see any basis for your allegations of "mudslinging" and a "personal attack". I will take note of your protest against me referring to your username and apologize for any discomfort you feel this single reference to your username has caused you. I will refrain from considering your username in the future.
Yours sincerely,
FF
I refer to your posting stating: "......but they are complicated, and necessarily use a high switching frequency, putting undue stress on components. Switching stress with its unwelcome high voltage transients and ringing, stresses components lowering their life."
The reference to your username was in my sentence(s): "As supported by "edbarx", the components in an SMPS are importantly stressed and you cannot just use another cheaper component in production without risk of hampering the overall reliability [no reference to you but to certain Asian production]. My personal impression is that is what sometimes go wrong with Asian SMPS."
I fail to see any basis for your allegations of "mudslinging" and a "personal attack". I will take note of your protest against me referring to your username and apologize for any discomfort you feel this single reference to your username has caused you. I will refrain from considering your username in the future.
Yours sincerely,
FF
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Yet, these days, active speakers sold with traditional transformer supplies number zero, none, none at all. They are ALL SMPS powered and number in the tens of thousands.
So someone must have found a way to do it right.
Jan
I don't buy that, sorry.
Decades ago, when the SMPS supplies were first designed into products as an alternative to traditional transformer supplies, they always were troublesome and failure-prone.
This is a fact, since I've had to repair them thousands of times in many electronic products.
VCR's, CD and DVD players, Televisions, etc.....
And now audio equipment included.
As they've evolved over time, I still haven't seen much in the way of increased reliability from them, however, they seem to last longer without failures in products that don't require high amounts of current, like the VCR's and CD/DVD units.
Once noteworthy exception is for computer power supplies, however their designs are much, much different than say, a subwoofer amp.
This is why I strongly believe that a traditional transformer-style supply is better off being used, for ruggedness and reliability.
Well,you talk about 'decades ago'. You talk about repairing equipment that is obsolete: VCR's, CD and DVD players.
I don't know what you 'don't buy', but 10's of 1000's of people are buying those active speakers with build in SMPS. In an era where a single returned unit on warranty can wipe out the profit of 200 sold units, it seems your view isn't corresponding to the real world.
Things change.
Jan
I don't know what you 'don't buy', but 10's of 1000's of people are buying those active speakers with build in SMPS. In an era where a single returned unit on warranty can wipe out the profit of 200 sold units, it seems your view isn't corresponding to the real world.
Things change.
Jan
The power converters used on satellites, with ultimate reliability, and the power converters used on passenger airplanes are evidently of the SMPS type. The converters used there are thoroughly tested before use and the designs scrutinized before any production.
These are evidently not commercial items but just show that SMPS can be made very reliable.
For commercial designs, it seems that design teams or individuals are often hired temporarily to do the job and may afterwards leave. Then, the production engineers take over with their task of reducing the production costs as much as possible and without the design engineers around, they may be tempted to use some cheap components that appear to be similar. Then, the failure frequency may increase importantly.
Also, I doubt that many manufacturers of commercial electronics regret deeply if their products break down after some 5-6 year and force the owner to buy new. My suspicion is that the SMPS is a frequent reason for failure of a commercial electronic apparatus.
I have transformers up to 50 years of age and even electrolytic capacitors about that old. All my transformers still work and very few of the capacitors have importantly degraded performance. With the very simple net-transformer type of power supply, little can go wrong. Even replacement of components is simple if the most obvious ratings are respected.
These are evidently not commercial items but just show that SMPS can be made very reliable.
For commercial designs, it seems that design teams or individuals are often hired temporarily to do the job and may afterwards leave. Then, the production engineers take over with their task of reducing the production costs as much as possible and without the design engineers around, they may be tempted to use some cheap components that appear to be similar. Then, the failure frequency may increase importantly.
Also, I doubt that many manufacturers of commercial electronics regret deeply if their products break down after some 5-6 year and force the owner to buy new. My suspicion is that the SMPS is a frequent reason for failure of a commercial electronic apparatus.
I have transformers up to 50 years of age and even electrolytic capacitors about that old. All my transformers still work and very few of the capacitors have importantly degraded performance. With the very simple net-transformer type of power supply, little can go wrong. Even replacement of components is simple if the most obvious ratings are respected.
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