Arcam AVR200 problems

[OXAUDIO]

To be more specific, the original fault was that the center channel would work
for maybe 10-15 minutes, then cut out. Operation could be restored by(quoting
the owner's words!)banging on the R H side, but the fault would recur.
I haven't yet pulled any circuit boards from the main chassis, but, does anyone have any idea as to the cause of this problem? At the moment the receiver
isn't working at all. A puff of smoke came from it, then it cut out. Since then
the mains(power)protection circuit trips a few seconds after switching on.
I suspect a filter capacitor across the Live & Neutral to be the cause of this,
but could be wrong! When this happened a pair of 8 ohm speakers were connected, plus a 15 ohm center speaker, although the speaker impedance switch was set to the 4 ohm position, but I wouldn't think that could cause
the unit to trip out.
By the way, does anyone have, or know where I can get, a schematic diagram
for the AVR200?

[jaycee]

Re schematic, Arcam themselves should supply it by email - they are really good with this.

Banging to make it work sounds like cracked solder joint. This has probably now fried the dodgy channel, which is why the unit no longer works. Arcam, like many, typically only put in a primary side fuse, so a channel being dead short might well trip your breaker if its sensitive.

[OXAUDIO]

I'll email Arcam, jaycee, thanks for the suggestion. As to the cause of the fault, you may well be right. I'll investigate further tomorrow. Just a small point, though-it's the
protection circuit in the receiver which is tripping. You may know that there is a relay
on the mains input PCB(on the rear L H side as viewed from the front, which is in the mains
supply line. That trips out. It even caused the 3A fuse in the mains plug to blow twice, although, given the rating of the AVR 200(1.7A @ 230v), a 5A plug fuse is probably a better choice.

[OXAUDIO]

Received a service manual via email today. Many thanks to the good people at Arcam. If only all manufacturers/Importers were that helpful!. Anyway the fault in the AVR200 turned out to be totally short circuit output transistors in the center channel amplifier, plus a fried 0.25watt resistor(R5103-330 ohm)I will get a new pair of 2SA1941/2SC5198
which, when fitted should get this receiver back to working order. No sign of any dry solder joints or fractured print connections, although I haven't(yet)checked the main P C B

[OXAUDIO]

Originally Posted by OXAUDIO

Received a service manual via email today. Many thanks to the good people at Arcam. If only all manufacturers/Importers were that helpful!. Anyway the fault in the AVR200 turned out to be totally short circuit output transistors in the center channel amplifier, plus a fried 0.25watt resistor(R5103-330 ohm)I will get a new pair of 2SA1941/2SC5198
which, when fitted should get this receiver back to working order. No sign of any dry solder joints or fractured print connections, although I haven't(yet)checked the main P C B

5 March 2011-Having obtained and fitted the new o/p transistors(and 330R Resistor!), there is still a fault in the center channel, which causes the amplifier's protection circuitry to trip, shutting it down completely, if a test
signal is applied to the center channel's i/p point on the 'AMP 1' PCB.
As some will know, this is not an easy item to take measurements on-the main amp. PCBs being virtually inaccessible when screwed in place. I have now removed the 'AMP1' board, on it's heat sink, connected it to the AC Supply from the mains transformer, and to 2 x 6 and 1 x 4 ohm speakers
ready to make further measurements, etc., on it. In the meantime can anyone suggest what might me the cause of the problem. The other transistors in the center channel check out alright 'cold', and no other components appear to have suffered. In addition to this, there is very little volume from any channel from either the internal AM/FM radio, or from
an external CD Player, or signal from an audio generator. Does this suggest
problems in an earlier stage, given that the front and rear channel power amplifiers are working normally?

[Chivvyp]

Originally Posted by OXAUDIO

Received a service manual via email today.

Don't suppose it's in a format that you could forward on to me? They didn't respond whan I requested one from them.

Regards

Pete

[OXAUDIO]

Originally Posted by Chivvyp

Don't suppose it's in a format that you could forward on to me? They didn't respond whan I requested one from them.

Regards

Pete

Evening, Pete,
I obtained the manual as a free download fromHiFi Engine | Download Free User/ Service Manuals, Amplifier, Receiver, CD, Tape, Tuner, Video You have to register
as a member, but, once having done so, you have access to service and owners manuals for a wide range of audio equipment, though you are not permitted to reproduce or otherwise use the manuals for commercial purposes
Michael
P.S. I've just realised that I obtained my manual direct from Arcam, so I don't know why they didn't reply to you, Pete. However you should have no problem downloading a copy from HiFi Engine

[OXAUDIO]

As a follow-up to my post #5 above, besides the faulty output transistors, one of the dual
emitter resistors(R5107-2 x 0.22 Ohm) was o/c. Replacing that, along with the 2SA1941 &
2SC5198, solved the problem. I completed the repair some months ago, and the amp. has
been working perfectly ever since. How I missed the o/c emitter resistor I don't know,
possibly because they seldom, in my experience, fail.
Incidentally Arcam can be contacted at http://www.arcam.co.uk