Philips FA930 becomes silent

[A K Bhattacharjee]

Hi everybody,
Hope all of you are doing well. The problem in my amplifier has started some 2/3 months ago. Sometimes output was normal & sometimes too low. Rather I can say volume was fluctuating. Sometimes one channel was OK but the other one was silent. Putting fingers below the amplifier & moving around helped bringing the volume back. The technician who looks after my electronics equipment tried to solve the problem by re-soldering some parts. In two occasions volume came back & the amplifier started functioning in a normal way. But after a day or two the problem started again. Now it is totally silent. Amplifier section is absolutely ok & all switches are functioning well. Only there is no output or sound is hardly audible.
Any help?

 

[lifewater]

100% your amp has got a track cut somewhere. If you have the requisite patience you can check all the tracks starting from any side of the amplifier. BTW was the amplifier shipped or had it suffered a fall.. a knock ?? because track cuts dont normally happen in a amplifier if it is not exposed to any knocks or mishandling.

On the hindsight you can check for dry solder too. Solder points should be shiny and not faded white with dry powdery appearance..

 

[efernand1]

Hi everybody,
Hope all of you are doing well. The problem in my amplifier has started some 2/3 months ago. Sometimes output was normal & sometimes too low. Rather I can say volume was fluctuating. Sometimes one channel was OK but the other one was silent. Putting fingers below the amplifier & moving around helped bringing the volume back. The technician who looks after my electronics equipment tried to solve the problem by re-soldering some parts. In two occasions volume came back & the amplifier started functioning in a normal way. But after a day or two the problem started again. Now it is totally silent. Amplifier section is absolutely ok & all switches are functioning well. Only there is no output or sound is hardly audible.
Any help?

How old is the amp? My neighbour has a Yamaha stereo amp which was purchased 25 years back and similar to what you described, same issues cropped up since the last 5 years....it seems to be failing components / capacitors etc. Neverthless, last round of servicing and repairs done and nothing much can be done should anything happen in the near future...right now it works..touchwood!

 

[A K Bhattacharjee]

How old is the amp? My neighbour has a Yamaha stereo amp which was purchased 25 years back and similar to what you described, same issues cropped up since the last 5 years....it seems to be failing components / capacitors etc. Neverthless, last round of servicing and repairs done and nothing much can be done should anything happen in the near future...right now it works..touchwood!

Yes, you are right. Myne also 25 years old. Although I have another amp but I love the sound of this amp. Technician has taken it to his workshop for repairing.

 

[reubensm]

Hi everybody,
Hope all of you are doing well. The problem in my amplifier has started some 2/3 months ago. Sometimes output was normal & sometimes too low. Rather I can say volume was fluctuating. Sometimes one channel was OK but the other one was silent. Putting fingers below the amplifier & moving around helped bringing the volume back. The technician who looks after my electronics equipment tried to solve the problem by re-soldering some parts. In two occasions volume came back & the amplifier started functioning in a normal way. But after a day or two the problem started again. Now it is totally silent. Amplifier section is absolutely ok & all switches are functioning well. Only there is no output or sound is hardly audible.
Any help?

As simple as it seems, from my experience with amplifier fixing, the key to being able to fix intermittent problems would be:
1) diagnosis - the ability to zero down on suspects based on the given symptoms
2) knowledge - experience with component failure, or partial failure or with components which will eventually fail and the associated symptoms
3) some basic test equipment, amplifier schematics (or comfort levels with typical designs)
4) access to spares
In your case, from my experience again, it can be due to"
1) dry solder on the PCB (usually not very dramatic and is often missed by the untrained eye)
2) PCB tracks will not break or fall off unless - some area of the PCB is getting hot during play, someone who does not know how to use a soldering iron or desolder pump/wick, desolders and solders, if you have sockets for inputs and outputs soldered directly to the PCB, harsh use may cause parts of the PCB tracks to fracture. You will have to dig into the history here.
3) corroded input sockets, output binding posts, etc
Only someone with component level diagnostic skills will be able to fix this issue. I once received a NAD 3020 amplifier which was very hard to fix. It had a PCB track fracture. One just could not locate the problem and it just kept blowing the output transistors of the right channel. After a lot of component level tracking and tracking, i managed to fix it. Here is the video of the fix.

 

[A K Bhattacharjee]

As simple as it seems, from my experience with amplifier fixing, the key to being able to fix intermittent problems would be:
1) diagnosis - the ability to zero down on suspects based on the given symptoms
2) knowledge - experience with component failure, or partial failure or with components which will eventually fail and the associated symptoms
3) some basic test equipment, amplifier schematics (or comfort levels with typical designs)
4) access to spares
In your case, from my experience again, it can be due to"
1) dry solder on the PCB (usually not very dramatic and is often missed by the untrained eye)
2) PCB tracks will not break or fall off unless - some area of the PCB is getting hot during play, someone who does not know how to use a soldering iron or desolder pump/wick, desolders and solders, if you have sockets for inputs and outputs soldered directly to the PCB, harsh use may cause parts of the PCB tracks to fracture. You will have to dig into the history here.
3) corroded input sockets, output binding posts, etc
Only someone with component level diagnostic skills will be able to fix this issue. I once received a NAD 3020 amplifier which was very hard to fix. It had a PCB track fracture. One just could not locate the problem and it just kept blowing the output transistors of the right channel. After a lot of component level tracking and tracking, i managed to fix it. Here is the video of the fix.

Hi Reubensm,
According to your suggestions, the technician who was trying to repair the amp went through every aspects but failed. Sound came for a day but went off the next day.
I want an expert advise from you. As I have already mentioned that my amplifier has become silent although other functions are normal. After receiving the service manual I wanted to check the amplifier according to the service manual. Service manual says press mute & loudness buttons simultaneously & press the on button. This will reset the system & will check the processor. When I did this the all the l e dsI(input lights e.g tape, phono etc) started blinking one by one. This was right, it was mentioned in the manual. Manual also says that the motorized volume control will go one step up & then will come one step down. Volume control knob went up one step but didn't come down one step. After this action, whenever the amp is switched on volume control starts malfunctioning. Motorized volume control knob automatically starts rotating whenever a button on remote is pressed.
Now the problem is, my tape deck is attached with this amplifier through ESI bus & I use to control the deck by remote since physical buttons of the deck start malfunctioning whenever I try to use them. since no technician in my town is able to repair the amp, I thought to use the amp to control the deck only. Obviously output of the deck to be connected with another amp. Now a new problem has started can u recognize the problem? or is there any way to stop rotating the volume control knob?
Regards

 

[reubensm]

I am more of a NAD guy but my suggestions were based the generic approach, which mechs normally take while repairing amplifiers. In this circumstance, one would need to run component-level checks internally to ascertain the actual root cause.