power tranny?

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rockgod212
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power tranny?

Post by rockgod212 » Thu Jan 04, 2018 5:31 pm

hello all, I thought I would post this question so others would know as well. I couldn't find any info on this, so here it goes.

im in the process of returning my metro 1959 clone back to stock plexi specs and I noticed my power tranny has this yellowish waxy film on the end bells, I can only assume that it is from the tranny laminations. what could have caused this? overheated tranny perhaps? is it anything to worry about? just curious about this before I fire it up again.
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danman
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Re: power tranny?

Post by danman » Thu Jan 04, 2018 7:36 pm

I have seen PT's ooze black, tar looking stuff after years of operation but they still seem to perform fine. In your case, I think that the manufacturers coat the transformers in clear varnish that eventually turns yellow over time. Kinda like how older guitars yellow a bit over time. The yellowing is likely from heating that occurs during the amp's use and will not cause any problems.

rockgod212
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Re: power tranny?

Post by rockgod212 » Thu Jan 04, 2018 9:10 pm

ok gotcha. good to know.
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Re: power tranny?

Post by rockgod212 » Fri Jan 05, 2018 11:59 am

I wonder if I can run 5 preamp tubes of that metro power tranny? does it have enough juice?
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neikeel
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Re: power tranny?

Post by neikeel » Fri Jan 05, 2018 5:30 pm

rockgod212 wrote:
Fri Jan 05, 2018 11:59 am
I wonder if I can run 5 preamp tubes of that metro power tranny? does it have enough juice?
In terms of HT certainly, in terms of heaters, x5 ECC83 is 1.5A, and EL34s need the same each, so looking at 7.5A heater draw, which is probably close but I think you will get away with it.
Neil

rockgod212
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Re: power tranny?

Post by rockgod212 » Fri Jan 05, 2018 6:51 pm

ok I will give it a shot then
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Re: power tranny?

Post by rockgod212 » Fri Jan 05, 2018 7:17 pm

would it help things if I went to DC heaters, as I just bought a board for that.
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Re: power tranny?

Post by neikeel » Sat Jan 06, 2018 8:34 am

rockgod212 wrote:
Fri Jan 05, 2018 7:17 pm
would it help things if I went to DC heaters, as I just bought a board for that.
Depends what mods you are doing, but most DC heaters still take their draw from the 6.3vac line at some point.

I think V1 in a high gains setting benefits from DC heaters. Never had to do it myself but I know George had to on the Metroplex.
Neil

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Re: power tranny?

Post by rockgod212 » Sat Jan 06, 2018 5:43 pm

my original goal of using 5 pre tubes was to have both stock plexi channels, then full on 800 channel with xtra stage. I know the ways of how to do it, was just wanting to do something different switching wise. I know I can do what I want with just 4 tubes though. running 5 tubes was just a thought really.
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