Diminuizione improvvisa del volume

[Cosimo]

Hi i’ m a very proud owner of Act-2 pre and a couple of Lp140m until today.
While i was listening a vinyl record suddenly i heard a big crack and the volume become lower.I’ve tried to hear a cd instead of vinyl and the volume is more high,but when i come back to phono(vinyl) it become lower again.
Anyone can help me in understanding what’ s happened?
Thank you
Ps:i don’t wanna hear compact disc

[admin]

If the volume change only happens with phono inputs, then it would be the preamp and not the amp. Also, if the volume is normal for everything else, then the damage would almost certainly be in the phone circuits of the preamp. Sounds like something blew. I would check the fuses 1st. After that, I would start checking the components of the phono circuit. I'm not sure if any of the tubes are strictly in the phono circuit as the manual for the ACT-2 doesn't say and I don't have the schematics, but I guess theoretically it could just be a bad tube as well.

You didn't mention whether you use a phono preamp or step up transformer (ie something that would be involved in the phono signal before it hits that ACT-2). If you do, then that could also be culprit. It would be easy to figure that out as you could then change the line level phono input into another input on the ACT-2 and it should have the same low volume effect.

If you open up the unit to inspect the circuit, make sure you do it safety with the unit unplugged. Look for burned out components, bulging caps, etc...

[AnotherJohnson]

There is nothing special about the aux/phono input on the ACT2 to distinguish it from another of the ACT2’s line level.

So move the CD input over to the aux/phono input and if it is good, then forget about troubleshooting the ACT2. It’s OK.

If turns out that the swap at the ACT2 does lead to continued problems with the aux/phono line level input, then the phono preamp and cartridge are probably OK. That’s the time to concentrate on the ACT2. It may be as simple as a fuse, tube, or (shudder ... a cap). It is really still early for cap failures in ACT2s.

If it’s not the ACT2, move to the next component upstream. You must have an RIAA equalization phono preamp there.

The problem is either in that unit (check the fuses first, then tubes if you have them, then caps), or it’s on the TT, probably a failure of the cartridge (which is rare). Look at the cantilever. Does it stand off with other it’s usual vigor? If it’s collapsed, which can happen (don’t ask me how I know ), it would give diminished output, but might or might not still allow the stylus to ride the groove.

Good luck with your troubleshooting!

[roberto]

Hola Chicos...

Reading the problem, also could be a power supply failure at the phono section. Because the problem is on both channels, and the problem was on both at the same time. An open resistor suppling the working voltage to the phono stage is my guess, but also could be other thing as you pointed out.

I will do an optical search inside and look for a possible open resistor. This resistor could be over heated and it´s colors could be deteriorated. Also, a double triode tube, could be the culprit. One side of the tube for each channel. Touch the tubes and all of them should be hot. The one that is not hot, it is not working. You can see also, the filament to be lit.

Happy listening!

[Cosimo]

Thank you,another question.Where are the fuses located?
On the rear side or inside the Act2?

[roberto]

Hola Cosimo,

The fuses are located on the input/output pc board at the back of the chassis. F1, the fuse for the tube circuit transformer is located nearest the back panel. F2, for the control circuitry, is located nearest the front panel. The correct fuse values are:

If configured for 100 or 120V:
F1 1 amp, slow blow
F2 1/2 amp, slow blow
If configured for 220 or 240V:
F1 1/2 amp, slow blow
F2 1/4 amp, slow blow

The tubes are: 4 tubes 6N30P.

Perhaps your problem is located at your phono preamplifier. The ACT-2 is a line stage Hi Level input only. Admin already pointed out this. My previous comment was not right, because I did assume that there was a phono preamplifier built in into your ACT2. There is not any phono preamp into your ACT-2. It is a line stage only.
Happy listening!

[Cosimo]

[Cosimo]

Hi everyone,just a little update.
Change pre phono=Zero result
Change pre ampli valves (all 4)=Zero result
Change exit for pre phono (tried in all exit of Act2)=Zero r.
Change cables from pre phono to pre amp=Zero result
The result is a background noise at lower level,and some “radio “ interference,
a very low volume when i hear the vinyl.
So i assume the problem is inside Act 2.
Thanks everyone

[admin]

What happens when you put the output phono preamp RCA cables into another input (other than phono) on the ACT2?

[Cosimo]

When i change input for pre phono (i.e. cd)the noise is the same.

[admin]

So that would indicate an issue that is independent of input pathway... which unfortunately makes it harder to identify.

You mention some "radio interference", there is a chance this could be a RF or EM interference issue and you need better shielding which could be cables or any other component in the line (unless it's only with vinyl in which case it could be a source component problem).