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Voltage selector of a Marantz 2226B amp

dankik said:
Hmmm... something doesn't make sense to me. What pins are connected when you switch to 120V?

View attachment 3252501
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I didn't mention one connection because it wasn't relevant in 220V and 240V mode. Pin 9 and 10 aren't used.

The selector in 110V mode connects:
pin 3 and 5 and 7
pin C and 1

The selector in 120V mode connects:
pin 4 and 6 and 8
pin C and 2

The selector in 220V mode connects:
pin 5 and 7 and 9
pin C and 3

The selector in 240V mode connects:
pin 6 and 8 and 10
pin C and 4
 
Could it be that the transformer is unbalanced in "230V mode" (i.e. the selector in 240V mode and the green wire connected to pin 7), because in that situation one primary coil is fully used and the other primary coil only partly?

A transformer can be unbalanced in two conditions:

Overloaded transformer: Overloading occurs when the current in one transformer section is much higher than in other areas. It can cause high temperatures and excessive losses in the insulation, terminals, and windings. When the transformer is overloaded, it can generate electromagnetic interference and electrostatic voltages.
Underloaded transformer: An under-loaded transformer is likely to experience a breakdown because of insufficient quiescent power or loss of power at high loads. A transformer is under-loaded when the load becomes too small to maintain the amount of energy that the unit requires. In some cases, the windings and coils can be safe from damage.
 
BassBias said:
Could it be that the transformer is unbalanced in "230V mode" (i.e. the selector in 240V mode and the green wire connected to pin 7), because in that situation one primary coil is fully used and the other primary coil only partly?
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Hmmm... I don't know the answer to your question.
Here are my assumptions:
  • Both sets of primary windings are around the same iron core.
  • The primary side should be independent of the secondary side, by that I mean that the electromagnetic energy is induced into the core and is transferred to the secondary independent of how many secondary windings there are.
  • I think that you can think of the primary coil as one long set of coil windings and that the jumper is "connecting" to select a different number of windings for the primary. (i.e. 240V has twice as many as 120V)
  • So, from that standpoint, I would think that the measured resistance of the top set of winding "should" be the same as the bottom set???
  • All this to say "I don't know why they are different"
  • Maybe someone else that has a 2226B European unit can check theirs to see if they are the same as yours.
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I can imagine that the top and bottom coil have the same number of windings, but that the bottom coil is winded on top of the top coil and therefore needs to be longer.
 
Can you move the green wire back to terminal 5 where it belongs and re=measue the resistances from blue-yellow, green-yellow, and blue-yellow just incase the wire and capacitance tied to pin 7&8 affect the ohms measurements.
 
Will do, but it will take some time, it is currently too hot in the attic to solder .

I don't think it will affect the measurements.

Btw I did build a Dim-Bulb Tester, what light bulb wattage should I use?
 
For your 2226B, probably a 60W-75W to start. It needs to be the old-style incandescent bulb... not LED.
BTW, I asked someone else about the difference between the two transformer primary readings and if he has see this.
 
dankik said:
For your 2226B, probably a 60W-75W to start. It needs to be the old-style incandescent bulb... not LED.
BTW, I asked someone else about the difference between the two transformer primary readings and if he has see this.
Click to expand...
Thanks, did you get a reply?
 
He suggested using an Agilent bench meter to measure the low resistance and also asked to make sure that the selector plug was out when making the readings. He did not have a multi-voltage 2226B to check. He also suggested using a Variac to slowly bring up the voltage to check for shorts. He also said that those selector plugs are a pain and had two customers where he had them hardwire the voltage selection.
 
dankik said:
He suggested using an Agilent bench meter to measure the low resistance and also asked to make sure that the selector plug was out when making the readings. He did not have a multi-voltage 2226B to check. He also suggested using a Variac to slowly bring up the voltage to check for shorts. He also said that those selector plugs are a pain and had two customers where he had them hardwire the voltage selectio
Click to expand...
Thanks for the advice!

Sadly I don't have a Agilent bench meter or other precise low resistance meter. Neither do I have a Variac . Probably someone else should have a look at the tranny, or I should "simply" replace it.

Can you ask him to measure the resistance of the primary windings of a similar multi-voltage 22xx series Marantz amp, it doesn't need to be the 2226B to get a better understanding.

Voltage selectors should be prohibited .
How does he hardwire them? I want to use a screw-type terminal block, good idea? And how and where do I bolt it to the chassis?
 
I messaged him, wait to see if he responds. Reading his reply again, it sounds like the jumpers were just soldering wires and covering with heat shrink tubing.
 
I responded! I have a multi voltage 2270 and it's open. I'll report the measurements (jumpers off). I'm betting they are the same for similar sections.

I will add that I've had those multi voltage selectors be rather flaky. I recommend bypassing it and "permanently" do a solder and heatshrink directly with the wires, getting them off of the plug, all of them used or not.
 
Finally got this done. The differences are most likely due to probe tip contact resistance differences. So it looks like it should be the same from one primary winding to the other and so that would make your transformer toast.

First primary:
Full winding = 1.530 ohms
Shorter tap to end = 0.302 ohms

Second primary:
Full winding = 1.682 ohms
Shorter tap to end = 0.342 ohms
 
Thanks @rBuckner. Did you measure this with your Agilent bench meter or Fluke DMM?
The OP readings are different for each primary, but also higher than yours. I don't know if this is because of his meter or what. It doesn't seem to be a short?

I already measured the resistance between the primary wires (with the selector plug removed):​
Top Coil​
yellow - blue: 3 Ohm​
yellow - green: 2.6 Ohm, green - blue: 0.6 Ohm​
Bottom Coil​
brown - orange: 5.8 Ohm​
brown - red: 4.9 Ohm, red - orange: 0.8 Ohm​
 
Thanks very much @rBuckner. Your measurements are lower and the same for both windings. So the 2226B transformer probably has become a paperweight.

But I saw that the first and secondary winding are also drawn equal in size in the service manual of the Marantz 2270 which is not the case in the service manual of the Marantz 2226B. So maybe the transformers differ (clutching at straws here, I know).

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