Arcam 2 Tuner

[Eaglesbush]

Just got hold of Arcam 2 Tuner ~ no manual ~
Everything seems to work except Volume output is very suppressed & requires threequarter turn before half decent volume is achieved

My other tuners all work to similar volume with just one quarter volume

Is this likely to be normal with this tuner? If not what is likely to be the problem?

Any advice appreciated

Cheers

[FrankGales]

Hi,
I have very good experience with the ARCAM service. They have sent me a service manual viy mail of a Delta 60 amp when I had a question. So you could contact them.

Good luck,
Frank

[Eaglesbush]

Thanks

Already done ~ I'll wait to see

[Peter_commtech]

Did you make any progress on this?

I have exactly the same modle and have the same fault only worse - turning up the volume on the amp to max means you can /just/ hear something.

I have investigated and found there is a FET which mutes the output right by the back pannel socket (one for each channel). This is permenantly 'active' ie muting the output. If I had a circuit diagram I could probably work out what's happening, but have not found one yet.

Cheers

[Eaglesbush]

Sorry No it never got solved

I did not think the effort of fixing it would be worth the time or expense so I bought another Tuner ..... Onkyo Integra T4970 .. which is superb sound .. but I don't have manual so I cannot program for remote control

(actually have German manual but translation is awful)

So if anyone has English manual / or can give me a copy / or can tell me where to get one I would be very grateful

Thanks

[Peter_commtech]

I did a bit more investigating after my last post and established that one of the muting FET's (Q2, Q3) was duff. ( These are on the PCB right next to the output sockets.) If one is faulty it will drag down the gate drive from R33 and so both channel will be affected (gate needs to be high to turn the FET off and bring the system out of mute mode.)

So, Like me you need probably one, and possibly two P channel JFET's type J174 (made by Phillips and others). I have not found a supplier yet. Significant characteristics are 30V rating and 85 Ohm Rds-on. I might try a 2N3820 that Farnell stock, it is only rated at 20V which is probably ok but the ON resistance is higher and not directly shown in the datasheet.

Good luck!

[anatech]

Hi Peter,
Consider using a small signal relay for this. Cleaner sound. Works whether the signal gets shorted to ground or passed through the fet. You just wire it differently. Drive the coil from the switching circuit, possibly add a transistor buffer if you need to.

-Chris