Oa-6 type 2a ...again

[Villee]

And I know that ZZ top perhaps is not the best sort of music to bass-energizers, but I also listen schubert, bach and so on But I have one idea, It would be perhaps a good idea to somehow improve bass-energizers cooling system with some kind of cooling element connected to the original cooling plate? Of course, there are not much room to do these additional cooling systems but I think that the original cooling plate is too small and perhaps this is some kind of mistake when someone designed this energizer, or a cost issue... Am I right when i assume that this poor cooling is the main cause why energizer´s transistors dies and make a short-circuit which then makes, for instance, smoke? And if you cool these main transistors and the whole circuit better, you have perhaps a chance to listen these speakers perhaps louder or does the 9710 then say "I cannot handle this anymore":D
Or is this volume problem mainly caused that the energizer has limited power what it can supply to the "bass" 9710?

I don´t have any more questions! : D

Ville

[svempa]

OK, so your transformer have dual secondary windings. The 0 cord as you call it is then made by connecting together the two wires closest to each other. That is the bottom wire of secondary 1 should be connected to the top wire of secondary 2. The outer wires of secondary 1 and 2 is then connected to the diode bridge. However if your transformer is exactly the one you linked to the secondary voltage is nominal 30V AC on each winding. Then I'm afraid the voltage after the diode bride will be something like +- 45V DC which is much too high for the amplifier.

[Villee]

Well thanks for the advice. I hope that we can cope with the possible 45 volts voltage. I haven´t this problem, when I connected secondary windings in parallel to the diode bridge, then the voltage was about 28 volts but now I understand that it´s highly expected that the coltage could be something like + / - 45 volts and then we have another problem, what a nightmare! But if we have this 45 volts voltage, are we going to again destroy the transistors and perhaps the whole circuit?

Ville

[Villee]

Hey all, I installed the transformer to the diode bridge as you advised me and the result was this: 30.7 volts between diode bridge´s + and 0. Is this something which is acceptable?

Ville

[Villee]

So i make things clear, the voltage was now +/- 30,7 volts after the diode bridge without anything else connected.

Ville

[jansch]

Villee, connect the elyt. capacitors and check the voltage again (DC). Dont connect the amplifier! You are probably NOT measuring peak voltage. When You add the capacitors you will have the "peak" Voltage in DC (30,7 x 1,41 = 43 Volts)

[Villee]

Okay so, if I have measure something like 43 volts it should be then pretty okay, eh?

[Villee]

Well electrolytics connected i measured something about 45 volts DC but my multimeter is a cheap biltema one so i assume that it´s not so precise?
So the voltage is perhaps not too bad? Well what should I do next, connect the amp or do some modifications to the power supply before it´s suitable?

Ville

[jansch]

It is to much! The DC voltage should be, according to specs, +32Volts and -32 Volts. ITs OK with 35 but not 45Volts! I have not checked what can go wrong....

If i understod, you don't have any theoretical background? If you have AC you normally measure the average voltage, the peak voltage is 41,2% higher if it is a sinewave. When you rectify, you use the peak voltage to charge the capacitor.Therefore, the specified AC output voltage from the transformer should be 23 volts AC ( + losses) in your case. A 2 x 25 Volts transformer is still OK and will give you +34 Volts and -34 volts DC.

So if you ask me.....Sorry, you should replace the transformer with a 2 x 25 volts transformer.......

[Villee]

Well, the reason why I chose too much voltage giving transformer was that I understood falsely the diagram, i understood that the 32 volts voltage should come from the rectifier as 32 volts voltage and that led to misunderstanding when i didn´t understand this peak voltage. But, so, when this energizer has 80 watts power consumption, is a transformer about 2x23 volts and 2x40 VA perhaps a adequately working replacement or is this also too effective to the amplifier?

Have to admit that I´m not an expert when building power supplys. I have earlier just repaired old tape decks, record playes and so on, chanced som caps and some potentiometers, tone arms and cardridges here and there, and some transistors but I have never had to replace a transformer so mistakes happen but you always learn something:D

So if I´m right I should spent some 50 euros and order new pair of transformers with dual secondaries, and then just build the power supply and i should have then suitable power supplys to the amplifier?

Sorry for bothering you all with my stupid questions