[kevin gilmore]

See this is why the extremes have to be split off from the rest of the stuff.
2 different schematics. The problem is that a mpx3 extreme and a ppx3 extreme
don't look like extreme extremes unless you look close.

The high voltage mpx circuit scares me too.

 

[HeadphoneAddict]

Quote:

Originally Posted by kevin gilmore /img/forum/go_quote.gif No the electraprint won't burn up as i have run the thing for 8 hours straight and it is just barely warm. But jack is right in OH so many ways about the original design. First the filament current peaks out of the transformer really are in the 32 amp range because of limited charging of the filament caps. (another well known vendor had this same exact problem a bunch of years ago). So you are definitely stressing the diode bridge which is getting warm and so on and so on. This is not how to do low voltage DC filaments. A better way would be to go with a higher voltage, bring the unreg DC up to 8 or 9 volts, then use a 5 amp linear regulator for each tube. An even better way is to use a 10 amp high frequency switcher, but some people don't like to do that because of possible interference generated from it. You can run the filaments with AC voltage. But then there are significant modifications to the circuit board necessary, everything has to come out of the box... Lots of work. This is what nate maher did with his menace. This is one of the many reasons i'm reluctant to work on these things.

Which is now TKAM's Menace, lucky bastage

 

[n_maher]

Quote:

Originally Posted by Bolder /img/forum/go_quote.gif Paul, I have sent E-mails to Jude, but I have yet to hear back from him. I will not post again here until I am contacted. Sorry if I violated any of the rules. I was only trying to help.

Hi there Wayne (at least I think it's Wayne). I don't believe that your contributions to this thread are in violation of the rules here so please don't feel the need to stop posting. As long as your posts are in compliance with the rules/TOS (see link at bottom of page) you don't need to wait for the MOT tag to be applied to your account. At least not in my opinion.

 

[Bolder]

Thank you, Nate.

It is Wayne.

I have just been notified that the EDCOR transformer I ordered two weeks ago has shipped. It should arrive on Friday. I'll take some pictures of it to post here so everyone can make up their own mind as to how it looks compared to the "stock" transformer.

I do not think I will have the time to mount it on the chassis. I will be out of town next week starting Monday.

 

[The Monkey]

Quote:

Originally Posted by mourip /img/forum/go_quote.gif I also believe that is his motivation but since he does a brisk business to DIYers it is a bit confusing. Modders and DIYers always work with some amount of risk. If I fried a new transformer by doing a replacement it would never cross my mind to blame the transformer.

The difference here is that he now knows the specific risk. Further, I doubt it's the repairer he's worried about, but rather the downstream or subsequent owner.

 

[mrarroyo]

Quote:

Originally Posted by kevin gilmore /img/forum/go_quote.gif If it is a 378x then you are fine. Would probably go 150K 1 Watt just in case the voltage is a bit high.

I will try to open the unit tomorrow or Saturday and post my findings. I will re-order the resistors to 150K 1 watt. Thanks.

 

[mrarroyo]

Quote:

Originally Posted by kevin gilmore /img/forum/go_quote.gif If it is a 378x then you are fine. Would probably go 150K 1 Watt just in case the voltage is a bit high.

Quote:

Originally Posted by mrarroyo /img/forum/go_quote.gif I will try to open the unit tomorrow or Saturday and post my findings. I will re-order the resistors to 150K 1 watt. Thanks.

Ok, after an agonizing 30 minutes I was able to remove the transformer cap an I found a Hammond 372BX ( Hammond Mfg. - Universal Primary - "Classic" Power Transformers ). I also installed a pair of 100K 1W resistors across the power caps, will place an order for 150K 1W resistors as was later suggested. Here are a couple of pictures.

Dr. Gilmore, should I replace the transformer? My favorite tube combinations are a 5670 driving a pair of 6BL7 or a 6SN7 driving a pair of 5687.

Thanks.

 

[Bolder]

I received the Edcor transformer today.

The bells ARE very blue.

Here is a shot of it next to the transformer it is going to replace.

Here is another picture of it turned 90 degrees.

This particular Extreme is a circuit board model with the "upgraded" 12 amp transformer. The Edcor should fit fine under the transformer cover. For those that have the smaller transformer, it won't fit inside the cover.

 

[Bolder]

Nice job, Miguel.

The diodes directly under the power switch look like they have been getting warm. The circuit board is discolored under them. I suggest you may want to check their rating and maybe replace them with higher current and voltage HexFREDs.

Two 6BL7 want 3 amps. Add in the driver tube and you are pulling above the rated current for your transformer. That may be why the filament diodes are discoloring the board. I would say that you should be using a transformer that allows more current to the filaments.

BE CAREFUL! There is voltage in excess of 300 volts that chassis.

 

[kevin gilmore]

Yep that is blue alright. Probably glows in the dark too.
It just might fit in there on the same mounting holes, hard
to tell.


On miguels unit,

I love that white wire in the middle hooked to nothing...

The resistors across the caps are exactly the idea.

This is a brighter picture than i have seen before, and the filament
diodes are definitely getting hot enough to damage the circuit board.
These probably should be replaced with 10 amp diodes, or better yet
a 20+ amp diode bridge mounted to the back wall. Problem might be
that there is not enough room between the fet and the iec input plug
to do that. If you mount it on the front the green wires may not be
long enough to reach, and would have to be extended. The transformer
is definitely running over spec, but not grossly overspec, so who knows
how long it will last.

The picture by frihed89 in the other thread is the minimum size diodes
you should be using. Not exactly sure of the part number. Also it might
be very hard to replace them without removing the circuit board so
the diode bridge wired into the top might be a better idea.

equivalent transformers with more filament current would be
372 dx 4 amps
372 fx 5 amps
372 hx 6 amps
372 jx 8 amps

Trouble is all of them are sizes bigger than the one that is in there so
you would have to drill and tap holes to mount them.

i would probably go with the 372 hx

with mikhail it seems it is never easy...

quickest long lasting fix is to just change out the diodes
and hope for the best, and when the transformer finally does
cause a problem, swap it out.

with the resistors across the caps the thing should be
safe to touch after about 30 minutes, but as always it
is much easier to measure with a voltmeter first.

With the unit powered, there is about 400 volts across the
big caps, and about 300 volts across the big solen cap.

 

[mrarroyo]

Quote:

Originally Posted by Bolder /img/forum/go_quote.gif Nice job, Miguel. The diodes directly under the power switch look like they have been getting warm. The circuit board is discolored under them. I suggest you may want to check their rating and maybe replace them with higher current and voltage HexFREDs. Two 6BL7 want 3 amps. Add in the driver tube and you are pulling above the rated current for your transformer. That may be why the filament diodes are discoloring the board. I would say that you should be using a transformer that allows more current to the filaments. BE CAREFUL! There is voltage in excess of 300 volts that chassis.

Quote:

Originally Posted by kevin gilmore /img/forum/go_quote.gif ... On miguels unit, I love that white wire in the middle hooked to nothing... The resistors across the caps are exactly the idea. This is a brighter picture than i have seen before, and the filament diodes are definitely getting hot enough to damage the circuit board. These probably should be replaced with 10 amp diodes, or better yet a 20+ amp diode bridge mounted to the back wall. Problem might be that there is not enough room between the fet and the iec input plug to do that. If you mount it on the front the green wires may not be long enough to reach, and would have to be extended. The transformer is definitely running over spec, but not grossly overspec, so who knows how long it will last. ...

Thanks for the feedback guys, I do not know if it makes any difference but I do not go past 8 clicks on the sttepped attenuator (10 o'clock) and only w/ the K501. With the rest of my cans I do not go past 6 clicks (9 o'clock). BTW, when you indicate I should upgrade the diodes do you mean:

Digi-Key - VS-HFA25PB60PBF-ND (Vishay/Semiconductors - VS-HFA25PB60PBF)

If ok to use these diodes will they be easy to mount on the same holes? How about orientation? Thanks, and sorry for all the newbie questions.

 

[kevin gilmore]

Electrically those diodes are great. Physically you are going to have
some trouble with them as they are only are a little less than .5 inch mountings.
You can measure the ones you have, they sure look like .8 to 1.0 inch mountings.
And you definitely have to get all 4 of them in the proper orientation. The bands
on the old diodes indicate the cathode.

Volume has absolutely nothing to do with power draw. Blast away at 110 db and
the power difference is unmeasurable.

From the picture it sure seems that all 4 diodes point the same direction
so orientation should be easy.

 

[mrarroyo]

I wonder if I could bend one of the legs and solder a jumper to attach that end to the board while the other end is soldered to the board. What do you think?

If anyone has four diodes for sale please let me know. Thanks.

 

[kevin gilmore]

this is all i have come up with so far...
625-FES16DT-E3

and you will definitely have to bend the pins creatively to get it to fit.
most of the rest of what i have found that is better is either not in stock or
200 piece or more minimum quantity.

Getting very hard to do decent diy design work when none of the parts are
available.

 

[John D.]

Quote:

Originally Posted by kevin gilmore /img/forum/go_quote.gif which plitron transformer? Don't remember a picture or any info on that particular transformer.

Like Happy Camper, I was also wondering about the plitron transformer for replacemnt on the standard Extreme.
Here's a link with pictures of the plitron.

Singlepower Extreme Platinum - Impressions - SGHeadphones