Can failing relays cause audio to drop out in an amp in addition to dirty switches?

onanysunday

Listen carefully
Hello,

I just recapped an Akai AM-73 Reference Master Integrated amp. Before the recap, it had issues with audio occasionally dropping out on one of the channels that could (temporarily) be fixed by repositioning or jiggling one of the dials on the front. So, when I was in there doing the recap, I also cleaned all those switches on the front panel with deoxit. This did seem to help a little, but the audio still drops out on occasion but not as much as it used to. I am always able to get it back by jiggling that same switch a little. I am wondering if this issue may be caused by a dirty or worn out switch in ADDITION to failing relays.

I am wondering whether replacing the two relays could resolve any remaining issues. I should mention the relays always "click on" 100% of the time on start-up AND the audio is still ALWAYS restored by repositioning the same, one switch- so it is very likely that the switch is 100% the culprit unless the relays are somehow tied into those switches where adjusting them also impacts (or effects) the relays as well. The relays are still available for purchase while the switches are not. I'm aware it may be a lost cause, but wanted to mention it to see if anyone with more experience on these matters could chime in. I will purchase and solder in those relays if it could help my issue. Thank you.
 
It could be the relay. Which switch causes the audio to come back? Sometimes if a relay is getting poor contact, hitting the loudness switch or increasing the volume will bring sound back in an intermittent relay. Could also check for bad solder connections for that switch. It can take a few deoxit cleanings of your controls if they're being pesky, so maybe start by cleaning another time.
 
It is the "Direct Operation Switch". It has 3 positions on it: D/A, Off, and Source. I mainly listen on D/A and when I slightly move it to the right towards Source and then move it back to D/A it always temporarily restores function. I did clean out that switch with three separate applications of deoxit while I was in there..

I haven't tried the loudness button experiment, but increasing volume will restore function about 20% of the time. Come to think of it, it does seem to act up more often at lower listening volumes and isn't as much of a problem when I am listening louder.
 
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It could be the switch going bad, but I'd still not rule out a relay. Could be that moving that switch jolts the relay a little. Next time it drops out, see if bumping the volume control brings sound back. If it's only responding to that one switch, then it's probably not the relay. If volume brings sound back too, then I'd look at the relay.
 
I will re-iterate the already posted sentiments. Clean the control again, and then investigate the relays--when relays get old and/or dirty, it takes a certain level of signal for them to "click"--and that can result in "drop-outs".
 
Be for cleaning again just for an experiment run the unit with the top off wait for the audio to drop out the tap on the relay (with a plastic or other non conductive piece) and see if the audio comes back on.

Any time I've had a dirty speaker relay when the audio drops out if the volume is turned up it suddenly comes back on. Very good sign of a dirty relay.
 
Ok, I will go back in there and clean the switch again and maybe tap on the relays if can get them to act up again with the top off. It sounds like it is a good idea to just go ahead and buy those relays anyway and install them because it couldn't hurt. FWIW, I did two applications of the deoxit red followed by a final application of the green faderlube..
 
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That would be great if I could fix this issue by re-cleaning the switch and/or soldering in new relays. I am hoping that it is not the switch itself that would need to be replaced, otherwise I would be out of luck. It is a very clean sounding amplifier with more headroom after the recap using carefully selected caps for the various sections.

UPDATE: Just ordered a new relay set from Germany. We will see how that works when it arrives.
 
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The "clicking" noise of a relay is the actual relay activating. Relay coils very seldom go bad. The more then likely suspect is the relay contacts themselves. These contacts will carbon up with age due to arcing. If so, they need to be cleaned and carbon removed. Another source of problems like you are having is the tape monitor loop, which seldom gets used, but can have major effect, causing drop outs. These should be cleaned with Deoxit once in a while, but more importantly, should be run thru a bunch of times (like 25 or 50 times) to clean the contacts. That whole chain of switches are in the preamp section and because they are seldom used, are a big source for problems.

'ner
 
If you can't find a replacement for the relays, if you can get the cover off you can draw a piece of paper soaked in deoxit through the contacts. In one case that did not work for me and I had to use 2000 grit sandpaper with deoxit but I would not recommend that. If that relay fails again I will have to either find a NOS or used one from a part out or else adapt a new relay with a different pinout.
 
I have a similar problem with my Marantz 16s. Cranking up loudness solves it temporarily. Relays need to be cleaned. These were never dustproofed when made.
 
I hope the replacement relay cures the OP's problem but if not, the switch that was jiggled to bring the sound back, could be making poor contact on the circuit board and a little solder would be all you need. (Fingers crossed)
 
My audio has been dropping out worse and worse since I've recapped it, cleaned the switches and have been using it more. Now, instead of just the left channel dropping out, both channels are dropping out at the same time and more often than they used to. I am pretty much convinced it IS those two relays. When it drops out, I press and depress the muting button and audio always comes back, so I know the volume level has the effect of either restoring or cutting the audio signal. Sounds like carbonized or pitted relay contacts (to me) from the helpful advice I've gleaned from contributors on this thread. If I recall, the relays are rather hard to access from when I had everything torn apart for the recap (I was looking for them and couldn't even find them on the board for quite a while) so I will just need to take my time with this project when they arrive in the mail.

Also, does anyone know why since the recap, my volume level has increased drastically compared to the same position on the listening dial than before? Once again, it could have to do with the relays, but I am not sure. Before, I would turn it up to about 10 o'clock on the volume dial to reach a reasonably loud volume. Now, I can't even go past about 8 o'clock before it gets Extremely loud. I am not complaining as it sounds terrific and clear (when the signal isn't cutting out on me) but was just curious why this happens. While keeping the same capacitance, I DID increase the voltage on the two main power caps from 63V to 100V (to increase headroom) if that has anything to do with it..

On a sidenote, does anyone know what determines wattage capacity on an amplifier? Does it have to do with the voltage of the main power capacitors, or something else? I am wondering if I increased my wattage handling capacity by installing those larger voltage caps?..
 
No, the wattage is determined primarily by the ratings of the output transistor(s). Now the power supply and all the other supporting parts have to be able to feed those transistors enough power and signal to reach that rating, to be sure.
 
No, the wattage is determined primarily by the ratings of the output transistor(s). Now the power supply and all the other supporting parts have to be able to feed those transistors enough power and signal to reach that rating, to be sure.

I wonder what could be causing my increase in volume since the recap? It is a 100w x 2 channel amp and it seems to have gobs of power to spare simultaneously pushing four speakers using speaker sets A + B. I have to say, I like the fact it is getting louder at lower levels- it seems there would be less distortion in the signal when the appropriate listening level is reached at lower volume dial position, am I right?

Come to think of it, maybe that is part of the issue..It is cutting out more now but I have also been listening at a lower volume position, maybe this ties into the relays again somehow acting up more at the "lower listening levels"..
 
The funny thing is that for the first 100 hours after the recap I was listening at the same volume dial position as before. Only yesterday did the change occur and it was suddenly much louder than before. Recently, after recapping and cleaning some (but not all) of the switches, I did turn all dials on the front back and forth dozens of times to clean them further after receiving that advice. Maybe that also had something to do with it. It is possible this whole time I was listening at a lower level due to some issue with some of the dials not having been worked for quite a while (if ever) and that I may have temporarily got a better relay connection despite the fact they're still failing, I am not sure..interesting to consider though.
 
It sounds like your old capacitors were on the verge of going bad. The recap just brought it back to life. General recaps always do this for vintage electronics.

If pushing or fiddling with the multi switch brings it back, then I would be cleaning it if you haven't already. Sometimes a switch gets so pitted that you have to really work it after a good deox.
 
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