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Old 10th September 2012, 07:36 AM   #361
GeirT is offline GeirT  Norway
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Default CCS resistor values

Hi,
I've finally commenced building my TramII kit. In the building of the PCB for the CCS'es I'm a bit puzzled about one of the resistor values. According to the schematics there shall be a 10 Ohm resistor on the reverse side of the potmeter. On the PCB itself a 1R value is printed at this location. However, in the package containing the CSS bits the only risistor value in the ballpark is 33 Ohm. Do anyone know if evolution has shown this to be a better value? I plan to run 45 DHTs first (for testing) and then swap to 2A3's after re-adjustments.

Geir
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Old 10th September 2012, 07:59 AM   #362
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Default CCS resistor values

Geir, I used the 10 ohm resistors supplied in the kit. See the Tram2 picture on the right hand side of the picture for the CCS 10 ohm value. You can just see the resistor value. I am using the Full Music 45 ST plated tubes. I have purchased the Rod Coleman Regulators. Desmo is the guru/master of mods for the Tram2. Have a look at his threads.
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Old 10th September 2012, 08:41 AM   #363
GeirT is offline GeirT  Norway
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Thank you for replying Ptashton.
I will then buy some power resistant 10 Ohms resistors then or temporarily run soem regular resistirs in parallell to give the correct value and take some heat.
Thank you also for the very detailed photo where I can study a feasible layout of the resistor arrangement at the DHTs.

I've also bought the Rod Colemans DHT heaters and will insert these later after ensuring that the rest of the pre-amp runs OK with the initial set-up. Just for info; the supplied DHT heaters from DIYHifisupply are the new ones with increased cooling area. Looks very neat but I guess they might not be as noise-free as Rods. I'll probably know when I tested and replaced in the future.

Geir

Quote:
Originally Posted by ptashton View Post
Geir, I used the 10 ohm resistors supplied in the kit. See the Tram2 picture on the right hand side of the picture for the CCS 10 ohm value. You can just see the resistor value. I am using the Full Music 45 ST plated tubes. I have purchased the Rod Coleman Regulators. Desmo is the guru/master of mods for the Tram2. Have a look at his threads.
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Old 10th September 2012, 10:11 AM   #364
Desmo is offline Desmo  Denmark
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With 45 tubes there are no heat or noise issues with the original DHT regulators, it's with 2A3 tubes there can be problems. My experience with the original DHT regulators was, that when I increased the cooling area, the noise dropped a bit (agin this is with 2A3 tubes). So I guess that the new regulators with larger cooling area will actually be more suited for 2A3 tubes than the older ones.

The big difference between the original DHT regulators and the Rod Colman is not the noise performance, the big difference is, that the sound is so much better with the Rod Coleman regulators. The lower noise is just a nice bonus...
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Regards, Morten
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Old 10th September 2012, 11:12 AM   #365
GeirT is offline GeirT  Norway
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Join Date: Aug 2011
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Thank you Desmo,
I will test both set-ups and report.

Geir
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Old 11th September 2012, 05:58 PM   #366
GeirT is offline GeirT  Norway
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Join Date: Aug 2011
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Hi again folks,
I've started testing the kit after assembling. My next challenge is that the B+ voltage out from the FCUPS module to the 6NP13 super-Mu follower tube is reading 400V and raising. The manual says the value should be 250V. The bias value of from the same power supply to the DHTs reads -110V while the manual says -74V. I've checked that the feeding voltages to the FCUPS is correct so the suplly from the main transformer seems OK.
Similarly is the heater of the 6NP13 also functioning.

Any ideas?

Best regards from Geir
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Old 11th September 2012, 07:14 PM   #367
forch is offline forch  United States
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Join Date: Aug 2010
Question on channel imbalance on Tram. I just replaced my Rev 2 filament supplies (one which burned out) with the Rev 3. All voltages are adjusted per spec, but it only produces about 1/3 to 1/2 the volume from the right channel, compared with the left.

A question:

I swapped tubes left to right, and used another pair of 2A3 with no change in channel imbalance.

I would like to receive some feedback on what to check on the unit to get it back in tip-top shape. This imbalance happened after I replaced the filament supplies (and it looks like both Rev 3 filament units are both operating properly. Thank you, Forch
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Old 11th September 2012, 11:08 PM   #368
GeirT is offline GeirT  Norway
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Join Date: Aug 2011
Location: Oslo
OK, things are resolving slowly here if I only read the testing procedure carefully ;-P.

My only nit now is to get the bias down to -74V (now its still -117v).
And the source selector /volume system is only switching occasionally (but remote works


Geir

Quote:
Originally Posted by GeirT View Post
Hi again folks,
I've started testing the kit after assembling. My next challenge is that the B+ voltage out from the FCUPS module to the 6NP13 super-Mu follower tube is reading 400V and raising. The manual says the value should be 250V. The bias value of from the same power supply to the DHTs reads -110V while the manual says -74V. I've checked that the feeding voltages to the FCUPS is correct so the suplly from the main transformer seems OK.
Similarly is the heater of the 6NP13 also functioning.

Any ideas?

Best regards from Geir
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Old 12th September 2012, 07:40 AM   #369
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Join Date: Oct 2006
Location: Karalee, Queensland
Default Bias Voltage e-mail from Simon DIYHIFI Supply

GeirT, I have the same voltage measurement in my Tram2, so I e-mailed Simon and this is his response. He asked his Technician to measure the Bias voltage from the FCPSU.


On 7/30/2012 4:12 PM, tpashton@bigpond.com wrote:


Simon, the Tram2 Manual will have to get re-written because there are people questioning the ‘Bias –73 volts’ when they are getting –110 volts from the FCPSU. It will clear up this mistake in the Tram2 Manual. Thanks again

Peter

From: Simon
Sent: Monday, July 30, 2012 6:06 PM
To: tpashton@bigpond.com
Subject: Re: Testing ABS FCUP Tram2 Boards

sorry i misunderstood. they measured -110v of FCPSU. It's correct.

regards,
Simon
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Old 12th September 2012, 12:36 PM   #370
GeirT is offline GeirT  Norway
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Join Date: Aug 2011
Location: Oslo
Ptashton, I'm so thankful for your reply!
Then I don't have to bother Simon concerning the bias.

This also means that the preamp functions as intended! As I finished it 2 AM last night I only listened to it connected to my headphone amp. It sounded nice and had real dynamics and punchy bass.

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