Marantz 2270 Slow to Click in...sometimes

[grailseeker]

Hello,

I have a Marantz 2270. It sounds great and seems to work fine, except sometimes the protection relay is slow to click in. Sometimes taking 10 seconds and occasionally up to a minute or more. The guy I bought it from said that his tech noticed it was slow, but said it shouldn't be a problem, it just takes its time getting warmed up. If that's the case, it's no problem; it doesn't really bother me.

However, I though it'd be nice to hear some other opinions on the matter. Is it acceptable behavior? Does it portend other problems? Or, is it really not that big of a deal?

Thanks

 

[audiojones]

No it's not acceptable behavior IMO. Measure the offset at the terminals leading into the relay from the amp as soon as you power it up. If both channels stabilize close to zero fairly quickly but the relay doesn't engage then it's most likely the timing circuit on the protection board (probably a weak capacitor that isn't charging / discharging fast enough or a weak transistor that isn't switching).

If the offset is high then that issue needs to be addressed as it indicates further problems in the amp circuit. It should be corrected as eventually it will stop engaging the relay altogether. The tech shouldn't have let it go like that, it's more than a nuisance that will most likely develop into a bigger problem.

EDIT - When measuring for the presence of voltage at the relay input terminals be extremely careful not to short any of the terminals together with your meter probe as you will not have the benefit of the protection circuit and you could damage the outputs very easily.

 

[petehall347]

No it's not acceptable behavior IMO. Measure the offset at the speaker terminals leading into the relay as soon as you power it up. If both channels stabilize close to zero fairly quickly but the relay doesn't engage then it's most likely the timing circuit on the protection board (probably a weak capacitor that isn't charging / discharging fast enough or a weak transistor that isn't switching).

If the offset is high then that issue needs to be addressed as it indicates further problems in the amp circuit. It should be corrected as eventually it will stop engaging the relay altogether. The tech shouldn't have let it go like that, it's more than a nuisance that will most likely develop into a bigger problem.

there shouldn't be any voltage at speaker terminals before the relay clicks in ..

 

[Robisme]

there shouldn't be any voltage at speaker terminals before the relay clicks in ..

Correct.

But, if it is DC keeping it in protection, you could still meter the speaker terminals and wait for the relay to kick in. Chances are the DC will still be high and dropping steadily.

Or, if you are comfortable, measure DC at the relay.

Could be a transistor or cap in the relay driver circuit as well.

Rob

 

[audiojones]

there shouldn't be any voltage at speaker terminals before the relay clicks in ..

That is why I said to measure for voltage at the terminals leading into the relay meaning the relay input terminals where the output from the amplifier connects to the relay. The presence of voltage here would indicate that the protection circuit is doing its job, and both channels must be checked as the amp powers up (shut amp down between checks). Of course there will be no voltage if measured at the speaker terminals since they are after the open relay contacts. I probably should have just said "terminals" rather than "speaker terminals", I can see how that can be misconstrued. I'll go back and clarify that with an edit.

 

[petehall347]

That is why I said to measure for voltage at the terminals leading into the relay meaning the relay input terminals where the output from the amplifier connects to the relay. The presence of voltage here would indicate that the protection circuit is doing its job, and both channels must be checked as the amp powers up (shut amp down between checks). Of course there will be no voltage if measured at the speaker terminals since they are after the open relay contacts. I probably should have said "relay terminals" rather than "speaker terminals", I can see how that can be misconstrued. I'll clarify that with an edit.

sorry for being picky but like you say it can confuse things ..
it was also mentioned voltage at speaker terminals after relay has clicked may be useful . and i agree ..

 

[audiojones]

No, you're absolutely right Pete and thank you for pointing it out, sometimes what's in my head doesn't make the translation onto the screen. It's easy to take it for granted that a lot of people don't work with this stuff every day so it's important to be very clear and concise when offering a troubleshooting tip.

 

[bryans12v]

I believe you're looking for the pins that the blue and yellow wires attach to on the relay. While both covers are would be a good time to let it warm up and adjust the idle current and offset.

 

[6taafondo]

To measure offset you can attch the multimeter leads at J757 (positive) and J758 (negative). Do this before turning on the device. Reading voltage at this points you'll be located before the relay so you'll notice what's going on right from switch on.
Measure on the same points on the left and right amplifier boards. Check out the image below as will help you locating these test points.

 

[grailseeker]

Thanks for the input, I will check the offset! In the meantime, after studying its habits for awhile, it seems that the relay takes much longer to click in if the receiver is cold, like if the AC is running and it's been off all night. Not sure if that gives an extra clue or helps isolate the problem. Just thought I'd pass on the observation.

 

[petehall347]

looking like its the timing capacitor at fault ... warm failing capacitors seem to charge quicker than cold ones ..

 

[Binkman]

Wonder why tech didn't fix it?
Service manual clearly states that the relay should click in about 5 seconds or so and protection circuit identifies C809 & R313 in the power supply. C809 is going bad 0.22 uf at 10v. Not uncommon for 10v caps to go with age. eventually it will.

 

[grailseeker]

I think the tech was very conservative about cracking things open, probably to a fault. It is within my skill-set to recap the power supply/protection board (that's the P-800, right?). Is there a parts list available for that board, by chance?

 

[Binkman]

Yes p800; the 'full version' of the sm at hifiengine has a parts list per components but you'll have to compare whats on the board to the listing anyway.

Might post over on the marantz forum maybe somebody has a prepared list for the p.s.?

 

[grailseeker]

tl;dr - Recapping the power board did not help (or hurt) the slow relay, it still takes somewhere between 10 seconds and over a minute to click in.

OK, now that the holidays have passed, I finally got around to recapping the power board. The first thing I noticed is that all of the big caps on that board had leaked all over the place. It was a real mess. Not sure if you can see all the old funk in the picture below:

I took this as a good sign that recapping would solve the issue. I cleaned off as much of the cooked-on gunk as I could and replaced the caps. Here it is with one left to go:

I also checked and adjusted the voltage, offset, and bias according to the service manual (is it just me or are the pins to check the idle current on newer production 2270s [sn 3901+] pretty tough to reach if those board aren't out?). None were that far off from the specified values before adjustment.

Unfortunately, this process did not change the time it takes for the protection relay to click in. It seems to vary based on temperature, so the first time I switch it on in the morning, it can take over a minute. Subsequent power-ups take less time.

There are a few things I noticed along the way that may be of value:

• R806 got flooded with leakage from C803. I cleaned it off and it appeared fine, but in retrospect, I probably should have replaced it. Could that have any bearing on the relay timing?
• I may have mentioned this in a previous post, but it maybe bears mentioning again: In the 2-4 seconds leading up to the relay actually kicking in, you can hear a kind of electrical buzzing with an escalating urgency that culminates with the relay click. This isn't a loud sound coming from the speakers, but instead a kinda subtle internal sound from within the chassis. For this reason, I did not think that the relay itself was the culprit (maybe I should have replaced it anyway?) since it obviously does its job when it finally gets what it needs.
• One of the big filter caps has a very flat top and the other is bowed ever-so-slightly upward. I would not go so far to say it was bulging, but it definitely has a little bit of curvature compare to the other one.
• I do still get intermittent and only occasional scratchy sound, mostly from the right channel, though the left has done it now and then, too.

Just wondering how y'all might proceed from this point, if anyone has any tips or ideas!

Thanks a million!

 

[petehall347]

make sure the correct value timing cap is fitted c807 220uf . check solder connections .
if its still bad try removing the flyback diode h813 that goes across the relay to see if it behaves any better .
if its still bad renew h808 h809 h810 .
but first be sure the dc offsets are in order ..

 

[grailseeker]

Thanks for the quick reply!
C807 is 220uf. The spec calls for 220uf/10V and my replacement is 220uf/25V.
So, when you suggest removing the flyback diode at 813, do you mean literally remove it and not replace it with anything? I know that would not be great for transistors, but is it okay for a relay? If so, why is it even there I wonder?

 

[NAD80]

Hello grailseeker. petehall347 is asking you to pull the diode to see if the diode is failing and causing the problem with the relay. You just need to lift one side of the diode to pull it from the circuit. Check the diode with the meter's diode check. It's there to curtail voltage spikes when the relay switches. Could you post some pics of the PS caps. Given that you found some bad caps already, they may already be on the way out. And due to the design of the amp if there are part failures could take out transistors and other parts.

 

[6taafondo]

The pics you posted are not showing. Something must be wrong with the links, or something else.

 

[Robisme]

That scratchy sound is DC. Have you checked the DC offset yet?

Separate the preamp from the amp and see what happens. There's a bad transistor somewhere.

Rob