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Author Topic: MP1 Classic | Hum in Dist. Tube Voicing  (Read 2575 times)

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MarshallJMP

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Re: MP1 Classic | Hum in Dist. Tube Voicing
« Reply #15 on: Time Format »

Schematic;MP-1 Classic Power Supply & Peak Meters section B4

On the PCB,on the right side of C186 (3300µF16V).It's one of those 4 big caps near the transformer,the one closest to the front.
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Griphook

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Re: MP1 Classic | Hum in Dist. Tube Voicing
« Reply #16 on: Time Format »

Thnaks for that info.
I just measured both the R382 and also the AC coming from the stepdown Transformator.

R382 has got 503kOhms which is the maximum tolerance of that Resistore right? I first have to find a local dealer who has Resistors with this tolerance.

And just for Interest, I got abot 113V AC coming from the Power Supply. Is this too high or just right?


Are the Voicing Curcuits seperated from each other or is this R382 an "over all" Resistor? And is there anything else I can check, before I start soldering, so I can just do it all in once?
« Last Edit: Time Format by Griphook »
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MarshallJMP

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Re: MP1 Classic | Hum in Dist. Tube Voicing
« Reply #17 on: Time Format »

Did you desolder one side of the resistor?You have to do this to get an acurate reading.Else you measure through other circuits.

I think the standard US voltage is 117V??But 113 should be fine.
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Griphook

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Re: MP1 Classic | Hum in Dist. Tube Voicing
« Reply #18 on: Time Format »

No, didnt de/soldered anything. Okay, so my measurement is not helpful at all ^^

Wikipedia says 120V O.o
But the Stepdown Trafo only provides 110V.

EDIT: To get that higher volume of TP9 I believe the R382 has to be lower than 499k?
Although I dont thnik so, can too less Power (110V instead of 120) damage my curcuit?
« Last Edit: Time Format by Griphook »
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MarshallJMP

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Re: MP1 Classic | Hum in Dist. Tube Voicing
« Reply #19 on: Time Format »

Not helpfull well not correct, I think it's even a bit higher.

The higher the resistance the higher the voltage.

Nah a lower voltage won't hurt.
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Griphook

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Re: MP1 Classic | Hum in Dist. Tube Voicing
« Reply #20 on: Time Format »

Since there is another topic with my MP1-Classic, I thought, I just replace this one too.
Do you think, a 499k 5% would be ok, instead of using 1%?
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MarshallJMP

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Re: MP1 Classic | Hum in Dist. Tube Voicing
« Reply #21 on: Time Format »

Well try to get as close as 499k
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