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post #1 of 7 Old 04-04-2019, 09:56 AM - Thread Starter
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Yamaha DSP-A1 home cinema amp - losing channels

Hello forum,

I've got two (long story!) Yamaha DSP-A1s and I'm having the exact same problem with both. When I first switch them on, I often get no sound through the centre or surround channels (not sure about the mains because I use the pre-outs to send the signal to a separate stereo amp). In general I can fix this by turning the volume up high - the sound suddenly appears from the missing channels (one after the other), and continues to work ok when I turn the volume back down. They work fine until I switch the machine off, but as soon as I switch it back on again the problem usually reappears.

No scratchy sound when I adjust the volume so I'm guessing (?) that the volume pot is ok. Loud clunk sound when I turn the amp on and a second clunk a few seconds later (which is when the sound comes on) - are there some relays making that noise? Do relay switches get stuck?

It's not fatal but it's a nuisance. In particular, I'm hoping to sell one of them soon and it'll be much more attractive to buyers if I can fix this. Just wondering if anyone knows what the problem might be and whether or not it's an easy fix.

Grateful for any advice, suggestions, etc.

Thanks
Alan
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post #2 of 7 Old 04-04-2019, 10:19 PM
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If it clunks before the sound comes, and it takes around 30 seconds or less, it's called an anti thump delay. Most good amps have them - they prevent the speakers from emitting a loud thump on power up, which could destroy them. This is solved by a circuit that disconnects the speakers from the amp - when the amp powers up, the speakers are disconnected. This allows the amplifier output to settle before the circuit connects the speakers, usually identified by a click coming from the amp.

It's a normal thing to happen. Big and beefy amps can have some serious power on transients as the power supply charges up and the transistors start getting their bias voltage and currents set and regulated. You want to keep these from the speakers themselves to prevent accidentally blowing them out.
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If it clunks before the sound comes, and it takes around 30 seconds or less, it's called an anti thump delay. Most good amps have them - they prevent the speakers from emitting a loud thump on power up, which could destroy them. This is solved by a circuit that disconnects the speakers from the amp - when the amp powers up, the speakers are disconnected. This allows the amplifier output to settle before the circuit connects the speakers, usually identified by a click coming from the amp.

It's a normal thing to happen. Big and beefy amps can have some serious power on transients as the power supply charges up and the transistors start getting their bias voltage and currents set and regulated. You want to keep these from the speakers themselves to prevent accidentally blowing them out.
Thank you. Yes, the clunks happen before the sound comes on. Do you have any advice on the problem of the disappearing channels? (would love to fix the problem)
Alan
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post #4 of 7 Old 04-05-2019, 11:15 PM
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Your problem sounds very much like an issue I had (along with many others, as it turns out) with my Yamaha RX-V1 receiver. It was behaving in the same manner as you describe for your DSP-A1. It relates to some internal switching that is built into the pre-outs to disconnect the internal amplifier when it believes you have connected it to an external amplifier. The switches apparently get dirty & don't connect. Turning the volume up sends a stronger signal, and can make the connection, until the next time of course. I also found clicking the speaker selector button on & off a few times on the receiver often cleared it up - temporarily.
I wasn't up for trying the more complicated solutions folks offered. I unplugged my unit, and used some tuner spray along with running the right size jack in and out of each of the pre-out rca connections to reduce any corrosion or dust build up inside - and that seemed to help a great deal.

Below are notes & advice from folks I found on-line and saved. I highlighted the basic approach I came across that worked for me . .

Yamaha RX-V1 Audio Channel Cutting Out Fix

Background: The RX-V1 uses an input board and RCA jacks that basically disables the internal amp when you use the pre-out jacks and try to use the Receiver as a pre-amp/processor Only. Needless to say, RCA jacks were never intended to have switches as part of their design. Yamaha, for reasons that I still don't understand, decided to make such jacks and implement this configuration.

Problem: The input board on the RX-V1 senses a marginal contact at these strange RCA switches for reasons such as loss of tension, corrosion..whatever. When you pump up the volume, the channel "bursts" back to life because the increased signal level suddenly becomes "valid" to the input board because the increase overcomes the marginal connection from the jacks. This is why people are reporting that "playing" with the jacks fixes it...for a while.

Solution: Using basic soldering skills, you simply need to jumper across the signal pins of each of the pre-out and pre-in jacks. I did it directly on the input board using neatly routed shielded wires while keeping the lengths to a minimum. This mod also allows you to use the RX-V1's internal amps while being able to use the pre-out connections for additional amps. In my case, I use a tube amp for my fronts driving fairly efficient speakers (JBL Jubals) while I use the internal amps to drive my front B&W 602s. The combination of the two is so sweet to my ears that I can not describe it beyond saying that the world class Jubals deliver a soundstage when driven by my Jolida while the Solid State amps in the RX-V1 and B&W 602s "fill in the blanks". This configuration requires some sort of attenuation in series with either of the amps in order to get the balance that the fronts need to please your ears and taste. I use the volume control on my Jolida to accomplish this.


One of the problems with the Yamaha RX-V1 and the loss of output to the various speakers..
(Main L&R, Rear L&R, others)on the back of the unit under preout/mainin jacks, most of these have switches on the back of the RCA jack's for channeling signals in or out.
I have two RX-V1 units and had problems with both.

The cure I used was to clean these switches using a good electronic spray that will not damage plastic components, then inserting a male jack into each one a few times to work the switches and believe me it will cure the problem. Obviously these switches become contaminated and need a good cleaning on occasion.

If you have access to the RX-V1 Maintenance Service Manual on page 64 (schematic Diagram) you will note the switch's on the back of the various RCA pin jacks.

The RX-V1 is a great AV Receiver and built like a tank.


Yes, there are relay type switches associated with those outputs. Your RX-V1 is not dying.
Just plug a pin plug in and out of the dead channel to bump the switch. You will hear the speaker
come on. If it doesn't come on,do the plug jack in an out of the pre out again. It will come on.
You can use the test tone to check all channels and rebalance volume levels. You are making the
pre out connect to its power amp. It seems the problem got better when activating those switches. Most likely a cleaning issue. You can also jump the mains and center, and there is also
a modification to jump all channels. I bought my RX-V1 very cheap because of this and love it.
Of course outboard power amp would solve all, but getting this reciever to connect to it's own
power amp has been thrilling as far as bang for the buck. I do use the front effects also, and like
them. It may seem like a pain, but it is worth it to get those channels going.
You can try all these temporary solutions but it is a real pain to lose you audio in the middle of a great movie.
I just fixed by RXV1 which was losing Center, Left and Right Surrounds. Mains never had a problem and Sub never had a problem.
Go to yamaha24x7(dot)com and buy 2 pcs of V806700 (black RCA connectors in PreAmp connctor bank); 4 pcs of V454850 (red/white RCA connectors in PreAmp connector bank).
Move the RXV1 to a sturdy work table (very very heavy!!). -Remove 4 screws from left chassis panel. Lift panel up and pull away from chassis to remove. -Remove right chassis panel the same way. -Remove top cover by unscrewing two top screws and two screws in top-rear corners. -Lift cover off and set aside. -Remove bottom panel by resting the RXV1 on right side and unscrew 12 screws holding in bottom plate. -While the chassis is tipped up, remove the black screw in near the middle support bar. This screw is found on the green circuit board near the support bar and is securing the audio board which you need to remove from the chassis. - Set the RXV1 back down such that all cards are up and visible. - There a a long string of black philip head screws between the PreAmp output connectors in the back (between the red and while RCAs). Remove all of them to be able to take out the audio card. - At this point, you will need to attach a ground strap from your wrist to the chassis to control static discharge and ruining your electronics. - The audio card is made up of two cards connected together. At the junction between the larger card connected to the main board, and the small card with all the connectors, gently separate the two cards by pulling the large card away from the small card. - remove the small wire connector at the top of the small card with all the connectors. -remove the large card from the main board by gently lifting from back to front (two inserting connectors in main board holding card). -I DID NOT remove the ribbon connector from the short connector card. I just place a board across the RXV1 chassis and did my unsoldering and soldering on this board. -I used a solder wick to remove the solder from lowest two (red/white) connectors, the next two black/black connectors, skip the connect with Black body (only one in this line), remove last two red/white connectors. - each connector is held in by 6 metal solder points plus 2 plastic holding tabs through the audio board. - Wick out all the solder from the 6 solder holes, and use a small flush cutting diagonal wire cutter and razor blade to cut off the plastic holders flush with the circuit board holes. - once loose, pull firmly to remove completely. Set this component aside and do not mix in with new components. - remove all of the lower RCA connectors except the 5th from the bottom. The solder pins on this is also different. - when reinserting the new RCAs, work from the one left up and down toward the outsides. This will make insertion easier. - Use a PC grade solder with resin and solder all the pins to the audio card. If pin is not visible, remove connector and straighten the pin to feed through the hole. - reinstall and reconnect the boards, - screw in card holding screw. -reassemble chassis.
Done. Good luck.


I recently gutted my RX-V1 to do a mod that gives me a pre out loop send and return for all six channels. What I found is that the pre-outs for each channel is a switched connector. When you plug in a RCA jack into the pre out, it lifts a blade in the jack that routes the signal from the pre amp back into the amp. So, when you plug in a cable, the amp input is lifted. Then, on the L,C,R channels, when you plug the cable back into the "in" receptical, the signal is routed back to the amplifier. I found that these switched connectors are made out of a chrome plated tin material and are suseptible to dirt and dust build up. IF you have a sudden volume loss in the future, you may want to try just plugging in a rca cable from the affected channel out to the affected channel in. If the level increases, then the dirt is your problem. You can leave the cable in permanently, or get some contact cleaner and spray it into the jack. While it is still wet, insert a rca connector in and out a few times. Make sure the contact cleaner you get is safe for plastics as some of them will destroy plastic. The ones that are safe for all plastics will say so on the label.
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Last edited by Rich86; 04-05-2019 at 11:20 PM.
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post #5 of 7 Old 04-06-2019, 02:01 AM - Thread Starter
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Originally Posted by Rich86 View Post
Your problem sounds very much like an issue I had (along with many others, as it turns out) with my Yamaha RX-V1 receiver. It was behaving in the same manner as you describe for your DSP-A1. It relates to some internal switching that is built into the pre-outs to disconnect the internal amplifier when it believes you have connected it to an external amplifier. The switches apparently get dirty & don't connect. Turning the volume up sends a stronger signal, and can make the connection, until the next time of course. I also found clicking the speaker selector button on & off a few times on the receiver often cleared it up - temporarily.
I wasn't up for trying the more complicated solutions folks offered. I unplugged my unit, and used some tuner spray along with running the right size jack in and out of each of the pre-out rca connections to reduce any corrosion or dust build up inside - and that seemed to help a great deal.

Below are notes & advice from folks I found on-line and saved. I highlighted the basic approach I came across that worked for me . .

Yamaha RX-V1 Audio Channel Cutting Out Fix

Background: The RX-V1 uses an input board and RCA jacks that basically disables the internal amp when you use the pre-out jacks and try to use the Receiver as a pre-amp/processor Only. Needless to say, RCA jacks were never intended to have switches as part of their design. Yamaha, for reasons that I still don't understand, decided to make such jacks and implement this configuration.

Problem: The input board on the RX-V1 senses a marginal contact at these strange RCA switches for reasons such as loss of tension, corrosion..whatever. When you pump up the volume, the channel "bursts" back to life because the increased signal level suddenly becomes "valid" to the input board because the increase overcomes the marginal connection from the jacks. This is why people are reporting that "playing" with the jacks fixes it...for a while.

Solution: Using basic soldering skills, you simply need to jumper across the signal pins of each of the pre-out and pre-in jacks. I did it directly on the input board using neatly routed shielded wires while keeping the lengths to a minimum. This mod also allows you to use the RX-V1's internal amps while being able to use the pre-out connections for additional amps. In my case, I use a tube amp for my fronts driving fairly efficient speakers (JBL Jubals) while I use the internal amps to drive my front B&W 602s. The combination of the two is so sweet to my ears that I can not describe it beyond saying that the world class Jubals deliver a soundstage when driven by my Jolida while the Solid State amps in the RX-V1 and B&W 602s "fill in the blanks". This configuration requires some sort of attenuation in series with either of the amps in order to get the balance that the fronts need to please your ears and taste. I use the volume control on my Jolida to accomplish this.


One of the problems with the Yamaha RX-V1 and the loss of output to the various speakers..
(Main L&R, Rear L&R, others)on the back of the unit under preout/mainin jacks, most of these have switches on the back of the RCA jack's for channeling signals in or out.
I have two RX-V1 units and had problems with both.

The cure I used was to clean these switches using a good electronic spray that will not damage plastic components, then inserting a male jack into each one a few times to work the switches and believe me it will cure the problem. Obviously these switches become contaminated and need a good cleaning on occasion.

If you have access to the RX-V1 Maintenance Service Manual on page 64 (schematic Diagram) you will note the switch's on the back of the various RCA pin jacks.

The RX-V1 is a great AV Receiver and built like a tank.


Yes, there are relay type switches associated with those outputs. Your RX-V1 is not dying.
Just plug a pin plug in and out of the dead channel to bump the switch. You will hear the speaker
come on. If it doesn't come on,do the plug jack in an out of the pre out again. It will come on.
You can use the test tone to check all channels and rebalance volume levels. You are making the
pre out connect to its power amp. It seems the problem got better when activating those switches. Most likely a cleaning issue. You can also jump the mains and center, and there is also
a modification to jump all channels. I bought my RX-V1 very cheap because of this and love it.
Of course outboard power amp would solve all, but getting this reciever to connect to it's own
power amp has been thrilling as far as bang for the buck. I do use the front effects also, and like
them. It may seem like a pain, but it is worth it to get those channels going.
You can try all these temporary solutions but it is a real pain to lose you audio in the middle of a great movie.
I just fixed by RXV1 which was losing Center, Left and Right Surrounds. Mains never had a problem and Sub never had a problem.
Go to yamaha24x7(dot)com and buy 2 pcs of V806700 (black RCA connectors in PreAmp connctor bank); 4 pcs of V454850 (red/white RCA connectors in PreAmp connector bank).
Move the RXV1 to a sturdy work table (very very heavy!!). -Remove 4 screws from left chassis panel. Lift panel up and pull away from chassis to remove. -Remove right chassis panel the same way. -Remove top cover by unscrewing two top screws and two screws in top-rear corners. -Lift cover off and set aside. -Remove bottom panel by resting the RXV1 on right side and unscrew 12 screws holding in bottom plate. -While the chassis is tipped up, remove the black screw in near the middle support bar. This screw is found on the green circuit board near the support bar and is securing the audio board which you need to remove from the chassis. - Set the RXV1 back down such that all cards are up and visible. - There a a long string of black philip head screws between the PreAmp output connectors in the back (between the red and while RCAs). Remove all of them to be able to take out the audio card. - At this point, you will need to attach a ground strap from your wrist to the chassis to control static discharge and ruining your electronics. - The audio card is made up of two cards connected together. At the junction between the larger card connected to the main board, and the small card with all the connectors, gently separate the two cards by pulling the large card away from the small card. - remove the small wire connector at the top of the small card with all the connectors. -remove the large card from the main board by gently lifting from back to front (two inserting connectors in main board holding card). -I DID NOT remove the ribbon connector from the short connector card. I just place a board across the RXV1 chassis and did my unsoldering and soldering on this board. -I used a solder wick to remove the solder from lowest two (red/white) connectors, the next two black/black connectors, skip the connect with Black body (only one in this line), remove last two red/white connectors. - each connector is held in by 6 metal solder points plus 2 plastic holding tabs through the audio board. - Wick out all the solder from the 6 solder holes, and use a small flush cutting diagonal wire cutter and razor blade to cut off the plastic holders flush with the circuit board holes. - once loose, pull firmly to remove completely. Set this component aside and do not mix in with new components. - remove all of the lower RCA connectors except the 5th from the bottom. The solder pins on this is also different. - when reinserting the new RCAs, work from the one left up and down toward the outsides. This will make insertion easier. - Use a PC grade solder with resin and solder all the pins to the audio card. If pin is not visible, remove connector and straighten the pin to feed through the hole. - reinstall and reconnect the boards, - screw in card holding screw. -reassemble chassis.
Done. Good luck.


I recently gutted my RX-V1 to do a mod that gives me a pre out loop send and return for all six channels. What I found is that the pre-outs for each channel is a switched connector. When you plug in a RCA jack into the pre out, it lifts a blade in the jack that routes the signal from the pre amp back into the amp. So, when you plug in a cable, the amp input is lifted. Then, on the L,C,R channels, when you plug the cable back into the "in" receptical, the signal is routed back to the amplifier. I found that these switched connectors are made out of a chrome plated tin material and are suseptible to dirt and dust build up. IF you have a sudden volume loss in the future, you may want to try just plugging in a rca cable from the affected channel out to the affected channel in. If the level increases, then the dirt is your problem. You can leave the cable in permanently, or get some contact cleaner and spray it into the jack. While it is still wet, insert a rca connector in and out a few times. Make sure the contact cleaner you get is safe for plastics as some of them will destroy plastic. The ones that are safe for all plastics will say so on the label.
Rich - thank you very much for taking the effort to put all that together. I’m very grateful. I don’t believe the RX-V1 was ever sold in the UK (unless it was given a different name here) so while I’ve google searched various Yamaha amps, I had missed all of the info you’ve been able to find.

Busy now but I’ll take the time to read through everything slowly and carefully as soon as possible.

Regards
Alan.
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