marshall stye power questions

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dcribbs1412
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marshall stye power questions

Post by dcribbs1412 »

Wanted to run this by anyone who knows or cares to comment...
Had some parts around decided to try a 6v6 plexi style...no can caps
using some axial caps I had...wondering about the power wiring.18 watt PT
I'm thinking...
bottom cap 32uf red wire to top of diode chain and standby switch?
twisted red pair to bottom diode chain
next cap 32uf I'm not sure about...thinking it runs to the top of the 10k power
resistor on the board but not sure.(I have it at the bottom of 10k along with choke and wire to 6v6's)
the next 3 white runs go to PI V2 and V1 all 22uf
I know this should be simple...but I'm cornfused again :oops:
any comments are appreciated

Thanks

Darin
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Structo
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Re: marshall stye power questions

Post by Structo »

Which schematic are you following?

Does this have a separate bias winding or are you tapping off of the HT for bias?

Typically, you run the HT leads from the PT to the diodes, two on each side, then to the first filter cap.
That node is your power tube plate B+.
Then if no choke then use a dropping resistor of around 5K 5W, that is your screen node.

The rest depends on your layout.

This is the schematic I used before.

It has the standby between the diodes and the first filter but many people think (myself included) it is better to have the first filter before the standby switch so that it can charge before dropping the high voltage to the rest of the filters.
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Tom

Don't let that smoke out!
dcribbs1412
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Re: marshall stye power questions

Post by dcribbs1412 »

Thanks Tom
sorry I'm a visual guy
been looking at different gut shots and pics
pretty much used a 2204 layout
the one you posted is one of the schems I referenced
I'm tapping off the HT for bias
I am using a choke
It has the standby between the diodes and the first filter but many people think (myself included) it is better to have the first filter before the standby switch so that it can charge before dropping the high voltage to the rest of the filters.
will do some research on how this might be done on my layout
still trying to understand the power section
Jana
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Re: marshall stye power questions

Post by Jana »

I prefer to switch the HV AC before the diodes (the bias tap isn't switched).
dcribbs1412
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Re: marshall stye power questions

Post by dcribbs1412 »

Thanks for the advise Jana
might try and wire that way when its up and running right...

I got it powered up
some voltages are not right most are close
bias seems to not go below 30ma center of pot either way increases bias
not sure I have it wired right got to figure some things out
now the fun stuff starts....
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ToneMerc
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Re: marshall stye power questions

Post by ToneMerc »

dcribbs1412 wrote: bias seems to not go below 30ma center of pot either way increases bias
not sure I have it wired right got to figure some things out
now the fun stuff starts....
Your bias supply has too much negative voltage, get that 220K out of the bias supply and try a 120-150K for starters. This should get you closer to the 18-22mA range.

TM
dcribbs1412
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Location: Arizona Desert

Re: marshall stye power questions

Post by dcribbs1412 »

Thanks TM
will do asap and report back

D
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