Quick question about 2270 Snubber

LuisNiels

New Member
hello everyone! i hope you don't mind the noob questions... does the snubber can go bad? mine is kind of bulged (see image)... does the snubber only protects the on/off switch? or it protects other components? and last question, what if i don't install a snubber (just temporarily untill i get a new one). Thank you everyone, and please forgive my bad english.

rKeVGSV.jpg
 
The snubber is just a film or ceramic capacitor, usual specs are .01µF @1KV, to lower noise. Bulge in body of a capacitor is a sign of throw-away-now. On the real old stuff, those caps leak (form parallel resistance) and can cause shocks if from chassis to AC line. In this case, you'll only benefit from lower noise if it's replaced with a new cap. This one is .1µF @500V it looks like. I'd get a film cap to replace it, but I see no big issue from not having it there. Of course, you'll want to go back in and put a replacement in, so I'd just wait until you get one and then let the music play. If the covers are off anyways, I think it's ok to use it without a snubber cap.
 
it's a .1uf - 120 Ohm 500V Thank you @EvanF for the info, and @tarior for the link, i wiil get the replacement :beerchug:

10 bucks seems steep for a power resistor and film cap. I was wrong about the purpose of the snubber, now I'm learning simething about these old Marantzes. Never had to replace a snubber on the 5 or so Marantz receivers I've worked on, fortunately.
 
It is steep. They used to be like $4.
These days I just solder a .1uF film cap in series with a half watt 120 ohm metal film resistor and call it good.
 
It is steep. They used to be like $4.
These days I just solder a .1uF film cap in series with a half watt 120 ohm metal film resistor and call it good.

i'm going to try this... other wise i will have to wait to order another batch of parts from mouser, at least 40 dls worth of parts to get the free shipping, it doesn't make sense to buy 1 $10 snubber + $30 shipping... Thanks again @tarior for the info
 
Will a faulty snubber cause a loud pop on turn off? In my case it is a Marantz 1070. I see on the blue snubber printed .1 + 120 ohms 500V . I take it that is .1 uf
 
A missing or defective snubber definitely can cause a pop at turn off. The reason for the pop is that if the switch opens at or near the top of the AC sign wave, the magnetic field in the transformer core can fall at a very high speed, generating a large voltage spike in the transformer windings. The large voltage spike in the primary winding will cause the switch to arc (eventually damaging the contacts), and the large spike in the transformer secondary voltages can generate noise in the receiver circuitry. The snubber resistor/capacitor network, or just a capacitor across the switch, limits the rate that the magnetic field in the transformer can drop to a reasonable rate, preventing the generation of voltage spikes.
 
Well...the primary purpose of a RC snubber array across the power switch is to extend the life of the power switch contacts by giving the energy of the collapsing magnetic field in the transformer a place to dissipate other than by an arc between the contacts, and also to squelch the arc generated by breaking the contacts under a load.
The 1070 has a muting/protection relay, that when the circuit is functioning properly, will break and disconnect the speakers from the amplifier before a turn off pop can be transmitted to the speakers.
In doing this for 20 years or so, I don't think I have ever seen any power off noises solved by replacing the RC snubber array. BTW, an X or Y cap alone won't really do much for your power switch. It needs to be a RC array.
 
There is no way that a mechanical protection relay can open before the magnetic flux in the transformer collapses and causes a spike in the transformer secondary's. and an arc across the switch, both of which create transients that can cause a pop, particularly if you are in a high gain mode like phono.
 
However, a relay can open before all of the power supplies completely collapse. Many units that don't have a relay will have a mute circuit that is fast enough to prevent a turn off pop, and it is very noticeable when it isn't functioning properly.
Like I said, in my experience, I have never seen turn on/off solved by replacing the snubber. If the fellow with the 1070 swaps out his snubber for a new one, does nothing else, and solves the problem, I will stand corrected. I am very confident that I will not.
 
I also suspect that it may not correct his pop, because the snubber caps in Marantz generally don't fail. I have seen other units with bad snubbers that did cause a pop, as the switch arced.
 
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Healthy discussion gentlemen. So happens that power switch was replaced with one that did not allow the wires to the relay to be connected ( that is what I think anyways) and probably confirmed by a photo of a switch from a member here at Audiokarma. So whoever installed this innapropriate switch just soldered these two wires together (that were probably removed from the original switch) and left them hanging thus connected to nowhere at that point. Seems to me then , that upon shutdown the appropriate circuitry was not turned off. I have a switch on order and will install and report back.
Paul
 
If the wire going to J709 from the positive rail is wired directly to the positive rail, then yes, expect incorrect function of the speaker relay upon power down. The positive rail filter cap is partly discharging through the protection circuit. Hack job.
 
Per the 2270 schematic, the two sections of the original switch both switch 120 volts. One switches power to the receiver, and the other switches power to the switched AC outlet on the back of the receiver. The power switch is not connected to the protection circuit in any way (except turning off the power which will eventually cause the protect relay to open ). After looking back at the original post, and the photo of the swollen snubber capacitor, I bet it is open. I think there is a good chance the pop is due to the transformer field rapid collapse, and a replacement snubber could correct the issue. The capacitor shown in the schematic and the one specified in the parts list is a 0.056uF 800V AC capacitor. The swollen one in the photo looks like a 0.1uF 500V. Looks like whoever changed the switch also changed the snubber capacitor.
 
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Umm...the DPST switch I see connects the positive rail to the protection circuit via J709 on the amp board. One of us may be looking at the wrong schematic.
 
I have been lookin in the schematic in the 2270 service manual. I also have a revised 2270 schematic for serial #s 1001 to 4900, and it shows the same DPST switch in the same configuration. My schematic shows power for the protect circuit coming from the transformer secondary connected to J804 and J805 on the P800 protect board, which is rectified by diodes H811 and H812, and filtered by C806.
 
I'm looking at the one on HIFIEngine. It shows the +34volts at C001 (rectified positive rail for output transistors/amplifiers) taken back to S004, DPST switch. One pole energizes the power transformer and switched outlet, the other connects the positive rail voltage to J709 of the protection circuit. If that were bypassed, it would function normally at power on, but would greatly delay the opening of relay (L703) at power off, thus certainly allowing transient noise through the speakers.
 
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