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Old 11th August 2013, 11:12 AM   #901
rab28 is offline rab28  Australia
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Quote:
Originally Posted by Desmo View Post
If some of you have Tram II's that can hardly deliver current for 45's you have faulty transformers and/ord heater supplies or something of that kind.
OK, i believe i have found the solution: Greg has been reading through the entire thread and mentioned to me today something about using different secondary windings for the heaters, but wasn't sure of the details.

Searching through the thread just now (i did read through it all myself last year, but the details are long forgotten), I found Bjarne's post (349) and Morten's followup (350), which teach us to use the 7.5V windings rather than the 5.5V windings.

Guess which windings my heater supply is using... Time to get out the soldering iron!

... and thanks yet again to the shared wisdom of Bjarne and Morten!

- richard
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Old 11th August 2013, 11:20 AM   #902
Desmo is offline Desmo  Denmark
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Well, there you go Always a good thing to make sure that all the ''basics'' are right before making conclusions that (in this case) the preamp is faulty and not designed right...

We have a saying here in Denmark that such problems are often ''fault 40'', meaning that the fault is about 40 cm away from where you think the problem is. Try to measure the distance from from your head when you sit staring into the preamp ''concluding'' that the preamp does not work
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Old 11th August 2013, 06:46 PM   #903
Desmo is offline Desmo  Denmark
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BTW rab28... When you connect the heater supplies to the 7,5V windings you should check again, if your resistors in the RAW supplies are the right ones to get the correct voltage going into the Rod Coleman regulators... You will need something like 0,15 ohm, maybe a bit bigger since you guys down under seems to have quite high mains voltage.
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Old 11th August 2013, 09:53 PM   #904
rab28 is offline rab28  Australia
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Hi Morten,

Quote:
Originally Posted by Desmo View Post
...before making conclusions that (in this case) the preamp is faulty and not designed right...
i was not suggesting that the preamp was not designed correctly: as you know, the 5.5V/3A winding is the one used by the stock filament supply, and presumably is able to supply enough current in that implementation... the issues arises when the stock supply is replaced by a raw supply and the Coleman regulator circuit. We had assumed that the 5.5V/3A winding would be sufficient for this modified circuit, but this is clearly not the case.

It was clear to me that something was not right about our implementation, since you and Bjarne did not have this issue. As i see it, our mistake was that we did not read through this thread thoroughly!

Quote:
Originally Posted by Desmo View Post
... you should check again, if your resistors in the RAW supplies are the right ones to get the correct voltage
Thanks Morten; will do -- although we are using a different raw supply circuit, so this may not apply....

As always, thanks for your continuing support.

- richard
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Old 12th August 2013, 12:38 AM   #905
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At least I was helpful for something

Cheers
Greg
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Old 15th August 2013, 02:56 AM   #906
kazap is offline kazap  Australia
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DIY DHT dampers

Click the image to open in full size.

The above tube dampers are often recommend and used on the Tram2.

I dont like them. I found they could possibly induce noise in the Tram2 DHT's and were also quite poor at absorbing vibration compared to my simple and inexpensive DIY design.

I found it was possible to induce noise with these dampers and to make this really obvious I linked two of the metal ringed dampers together and lowered them near a DHT while the Tram2 was running. Appreciable noise came out the speaker and induced noise volume correlated with distance from the metal ring of the dampers to the DHT. When actually placed on the tube the metal would be even nearer. Noise can be expected to be less without the two linked vertically, but in my mind its still a failed design for the Tram2 if any noise can be induced.

I got a better result using lead sinkers (No.2 is a good size) covered in blutack. The sinkers didnt act like an antenna for EMI and the high density gave good inertial dampening to vibration. I found it best to stick the sinkers on with blutack. Blutack seems to add to the deadening effect. For safety I covered the lead entirely with blutack in case they fell off and chipped the chassis. The DHTs did not run any hotter with five on as measured with a laser thermometer. The sinkers can be stuck on anywhere so I placed them asymmetrically to prevent standing wave resonances. They gave excellent dampening.
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Old 20th August 2013, 04:28 AM   #907
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Quote:
Originally Posted by Desmo View Post
I'm looking into Mu tubes... The Chatham Electronics 6AS7G are very nice sounding, and should be some of the best 6AS7G types. Then I read that 5998 can be replaced for 6AS7G, and to make it even more complicated, then 5998 is sometimes labeled 2399 - like the Chatham Electronic I just bought. The 5998 / 2399 has totally different internal construction than 6AS7G, so I was a bit skeptical when installing in my Tram II yesterday, but there is music Time to burn in the tube, it will be interesting if it works even better than the Chatham Electronics 6AS7G

PS...Interesting with the GZ33 rectifiers, let us know what you think of the sound as they (and the Philips) burn in. In my experience the Philips changes quite a lot, maybe the same goes for the GZ33...Tizzy cymbals is not something I hear with the Philips, actually quite the opposite. What I like so much with the Philips is it's very natural and coherent sound where nothing ''stands out''...
Hi Morten,
I have been looking back through the thread and I am unable to find your updated impressions on the Chatham 5998 domino plate?

Cheers
Greg
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Old 11th September 2013, 06:08 AM   #908
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Hi Guys,
Well here is where I am at and by all accounts I am high and dry. I have acquired all the necessary parts apart from the FCUPS from DIYHIFI Supply as a friend had a spare board available. Well as it turns out the board had been thrown out as he had it replaced a while ago. Initially I thought oh well there are bigger problems in the world and I with the help of Simon would be able to build an FCUPS. I received a schematic for the 2008 FCUPS and all was on track however after a brief email conversation, Simon mentioned that there was some modifications to be done to the board and has left it at that.......

I know that the C1, C2 and D9 have to be removed however the emails have become quiet and I just do not know where to turn. I am hoping that perhaps one of you may be able to help. As it is Thorstens design perhaps he may be able to chime in.
There must be a way of ensuring that our trams are maintained well into the future.

Well its out there in the big old universe fingers crossed all will work out for the better

Thank you all for your help.

cheers
Greg
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Old 15th September 2013, 03:39 AM   #909
reggie is offline reggie  Australia
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Hello Greg.

I believe Simon has been absent on a business trip until 9/11/13. I hope he resumes dialogue with you

Reggie
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Old 15th September 2013, 06:12 AM   #910
Mihan is offline Mihan  New Zealand
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Hi Greg
I too, have the earlier schematic and version 1.0 of the FCUPS board and would appreciate having the modifications if you manage to get them thanks.
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