Hi
I have a WADIA 12 that was plugged in with incorrect input voltage and the transformer got damaged. I really like the sound of the DAC and would like to fix it is possible. Does anyone has the transformer specs for it? The transformer is marked as EL48/16.8 10 VA. I found some suitable ones but need to know secondary voltages. If someone that has a working unit can measure the secondary voltages would be much appreciated. Looked everywhere for the schematics without any luck.
Thank you
I have a WADIA 12 that was plugged in with incorrect input voltage and the transformer got damaged. I really like the sound of the DAC and would like to fix it is possible. Does anyone has the transformer specs for it? The transformer is marked as EL48/16.8 10 VA. I found some suitable ones but need to know secondary voltages. If someone that has a working unit can measure the secondary voltages would be much appreciated. Looked everywhere for the schematics without any luck.
Thank you
Perhaps the voltage ratings of the voltage regulator chip and filter capacitors can provide some clues.
https://www.eratransformers.com/product-detail/18#
https://www.eratransformers.com/product-detail/18#
Thank you for your reply and the link.
I think the type 3 or type 4 from the link would be suitable but just wanted to be on the safe side…
Regulators are 7805, 7905, 7810 and LM337
Would be great if someone has a WADIA 12 and could measure the transformer outputs
I think the type 3 or type 4 from the link would be suitable but just wanted to be on the safe side…
Regulators are 7805, 7905, 7810 and LM337
Would be great if someone has a WADIA 12 and could measure the transformer outputs
Edit: Sorry.. I found a bad link
It looks like type4, with two secondaries. As you have a pair of 5v regs for +/- voltages. Then a 10v reg, which could well be a sumation of the two outputs. It's the 337s use that has me rubbing my chin. There is a wadia player drawing around here, that could shine some light on that. I guess it's a non-standard voltage, but with your board alone, you could likely see what caps are on the output of the 337. Giving an upper limit of the tx in use.
Edit: I'm guessing you had a pair of 110 primaries in parallel, instead of series when you used 220. Is one of these primaries still alive?
I must sleep.. I hope I'm not talking nonsense
It looks like type4, with two secondaries. As you have a pair of 5v regs for +/- voltages. Then a 10v reg, which could well be a sumation of the two outputs. It's the 337s use that has me rubbing my chin. There is a wadia player drawing around here, that could shine some light on that. I guess it's a non-standard voltage, but with your board alone, you could likely see what caps are on the output of the 337. Giving an upper limit of the tx in use.
Edit: I'm guessing you had a pair of 110 primaries in parallel, instead of series when you used 220. Is one of these primaries still alive?
I must sleep.. I hope I'm not talking nonsense
Last edited:
Just a wild guess:
I would expect that the analog stage at the output is driven from a separate voltge. +5V and -5V may be it.
You should be able to follow that.
The ten volt may be filtered, somewhere on the board, again and serve the digital stuff.
The 337 could drive a clock.
All these circuits may be driven by 2x12V AC, but in most cases I found them to be 2x15V . So the unregulated voltage should be around 22V DC, with 35V capacitors.
Have a look at the secondary winding, how many points are there. I expect 4, two joined in the middle.
I would expect that the analog stage at the output is driven from a separate voltge. +5V and -5V may be it.
You should be able to follow that.
The ten volt may be filtered, somewhere on the board, again and serve the digital stuff.
The 337 could drive a clock.
All these circuits may be driven by 2x12V AC, but in most cases I found them to be 2x15V . So the unregulated voltage should be around 22V DC, with 35V capacitors.
Have a look at the secondary winding, how many points are there. I expect 4, two joined in the middle.
The second from the left in the upper row may just be a screen. Check the resistance of the secondary windings.
I'd suggest taking the DAC along trafo to a qualified mechanic, they used to put a wire fuse inside transformers back in the day. If this trafo has the same wire fuse it could be fixed.
Two bridge rectifiers are being used on the positive side its 7805, 7810 and 337. Realizing that there is an altera chip in the DAC my hunch is that 337 is probably configured for 3.3 volts. As for negative side regulator no idea.
Two bridge rectifiers are being used on the positive side its 7805, 7810 and 337. Realizing that there is an altera chip in the DAC my hunch is that 337 is probably configured for 3.3 volts. As for negative side regulator no idea.
3.3 Volt makes sense, too.
If you can get a transformer with such a screen between primary and secondary, that would be fine. Anyway, I don't think there will be much of a difference if you only use a 2x12V AC transformer without screen.
I don't know how much you know about that stuff. If you want to keep the DAC 100% origional, you need a quite rare transformer. You could use a 120V primary just as well, but disable the voltage changing thing. So you may get away with a quite cheap, basic transformer.
If you can get a transformer with such a screen between primary and secondary, that would be fine. Anyway, I don't think there will be much of a difference if you only use a 2x12V AC transformer without screen.
I don't know how much you know about that stuff. If you want to keep the DAC 100% origional, you need a quite rare transformer. You could use a 120V primary just as well, but disable the voltage changing thing. So you may get away with a quite cheap, basic transformer.
I do have handy a small toroidal with secondary 15vx2. I will try it
The original transformer got really hot and smells awful. Is cooked
The original transformer got really hot and smells awful. Is cooked
https://somanytech.com/lm337-calculator-online-external-resistor-calculator/
It appears to my uneducated eye, that the output of the 337 circuit isn't related to the input. Instead, it uses an internal reference, so differences in the supplied voltage, don't effect it's output. This online tool can perhaps tell you right away, what voltage it will produce, and so what transformer would be most suited. We don't want to go too high, or excess dissipation will warm the regs. Though I suspect they will all take this 15v transformer for the brief time it takes to see what the 337 creates. Thus verifying what an appropriate transformer would be. My only concern is where the 10v reg lives. I'm seeing 35v max for 5v ones, but some of them 10s are 25v max. A 15vac is getting a bit close. I would have my meter in place as I power on, and get my figures instantly, and power off. Or, I would use my variac, which is always handy.
It appears to my uneducated eye, that the output of the 337 circuit isn't related to the input. Instead, it uses an internal reference, so differences in the supplied voltage, don't effect it's output. This online tool can perhaps tell you right away, what voltage it will produce, and so what transformer would be most suited. We don't want to go too high, or excess dissipation will warm the regs. Though I suspect they will all take this 15v transformer for the brief time it takes to see what the 337 creates. Thus verifying what an appropriate transformer would be. My only concern is where the 10v reg lives. I'm seeing 35v max for 5v ones, but some of them 10s are 25v max. A 15vac is getting a bit close. I would have my meter in place as I power on, and get my figures instantly, and power off. Or, I would use my variac, which is always handy.
After installing the 15x2 transformer the dac powers up ok. I measured this values
337 output -1.9v
7810 9.98v
7805 4.98
7905 -2.4
Everything stays cool and does not get hot.
After leaving it for some time I connected the dac to my system
No sound from optical
Spdif outputs sound but low in volume and very thin
337 output -1.9v
7810 9.98v
7805 4.98
7905 -2.4
Everything stays cool and does not get hot.
After leaving it for some time I connected the dac to my system
No sound from optical
Spdif outputs sound but low in volume and very thin
It seems that the 7905 may be damaged. Have you measured the input voltage of the 7905 and the output voltage of CR2 and CR3?
7905 input voltage is -3.5v
CR2 20v on the positive 0 on negative
CR3 18v on positive -3.5 on negative
CR2 20v on the positive 0 on negative
CR3 18v on positive -3.5 on negative
The 7905 must output - 5V. You have to review that part to be sure.
Maybe IC 7905 is defective, check with IC 7905 to see if it works.
Please post in English.
@vintagejapan
Have you measured the resistance of the left secondary winding of the fried transformer if the second pin from the left is actually the screen or center tap?