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Closed - Megatron and GRHV PCB GB


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Got my boards today. Thank You! I have posted pics before but here are some more of my build. I noticed these boards have a 12 V for the filaments. The old board did not have it.  

12v filament version posted pretty sure the original was done the way it was to accomodate the 6dj8 tubes for those that wanted to do that edit: the filaments of the output tubes are tied to

All international-destined packages have been sent too. I'll PM each with the postage. Happy building!

Posted Images

 

51 minutes ago, eggil said:

I don't know how I missed this. If I could have 2 Megatron boards and 2 GRHV would be greatly appreciated.

Thank You.

No worries. Will add you to the GB.

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GRHV board order has been placed with Seeed. Will provide update when boards arrive. 

I will be putting together a BOM on Mouser for the Megatron amp when I have time. I'll share the BOM when it's done.

There should be GRHV BOM already in the forum. I remember building one for the dual board so the difference will be in the connector blocks. 

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2 hours ago, steefdebruijn said:

Hi,

I already created one. Please check and advise. Does NOT contain

  • the 2SA1968 (ordered from bdent)
  • the C1815
  • tube sockets

Also does NOT YET contain terminal blocks.

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=87e75194b6 

Steef

Great! Took a quick look. Don't think we need 1W resistors in most locations. In fact, you may have problem fitting them.

Many builders here use either Vishay RN60 or Koa Speer MF resistors. Both are 1/2W and fits the board well.  

Also, you can use KSA1156 or STN9360 to substitute the 2SA1968. Just need to mount them observing the pintout difference.

EDIT: the CMF60 resistor is pretty compact for its 1W rating at 8.74mm length so should fit the board fine.

Edited by mwl168
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It dawned on me while I was trouble shooting my GRHV to put a reminder here.

The 3W 5.1 R current limiter on the GRHV board is good for 120mA per rail which is a bit low for the Megatron and not enough for the Blue Hawaii 's negative rail. May need to go to 3R or lower. 

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The amp boards were delivered tonight. Too late for me to take photos but the board is nice and heavy as can be expected given the 4oz copper.

The GRHV boards are supposed to arrive tomorrow. Will take some photos if I get home in time.

By the way, please PM me your shipping address if you did not include it in PM or PayPal note to me.

Thanks!

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On ‎22‎/‎05‎/‎2017 at 4:24 AM, mwl168 said:

It dawned on me while I was trouble shooting my GRHV to put a reminder here.

The 3W 5.1 R current limiter on the GRHV board is good for 120mA per rail which is a bit low for the Megatron and not enough for the Blue Hawaii 's negative rail. May need to go to 3R or lower. 

I´m doing a GRHV for GG and BH and I ´m thinking run both with 450v and 120mA, (I used 4 cap 550v/680uF so I think that it´s correct for 450 volt output) but now I have a dude with the negative current resistor.   

For negative rail. Do I need change the current resistor for a low value? If I change this resistor, will I have problems with GG?.

 

 

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On my builds, the Blue Hawaii draws just over 80mA on the positive rail but close to 150mA on the negative rail. The Caron draws around 100mA on both rails. I use the same PSU for Carbon, KGSSHV and Blue Hawaii and will be for the GG as well.

The 5.1R current limiter is good for about 120mA and works fine for the Carbon but not for the negative rail of the Blue Hawaii. I paralleled a 15R with the 5.1R on the negative rail to get about 3.8R to support the Blue Hawaii. 

I have not completed my GG build so don't know what the current draw is. Maybe someone will chime in. 

Edited by mwl168
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the BH has the extra power supply on the amp boards that takes power from the negative rail, so hence the increased current.

all the rest of the amps should have roughly the same current in both power supplies

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On 2017-5-26 at 7:20 AM, Whitigir said:

Any plan for chassis and or transformer group buy ?

I ordered some transformers for me and a friend of team spain two weeks ago and I have them since last Friday, the bigger trafos have these secondaries, 2x [email protected] and 1x [email protected], the others have 2x [email protected]

I haven’t a PSU board to check these HV trafos in this moment and I've only connect these toroids to 230Vac, the result with no load, no noises in the 4 units, the voltage difference between 360v secondaries is less than 0.1v, and the same voltaje in the 18v outputs (in both HV trafos), I can't tell the same of the Toroidys because I have some units with a little noises, and all toroids that I've bought to this people have a little bigger voltage differences in the same outputs than these Torivac trafos.

I ordered these toroids with a "generic" specs and, by default, the Torivac trafos haven't a earth wire in the electrostatic shield (I'm not sure that it's a big problem or not). I asked why these trafos not mount this wire and they respond that it's a optional improvement like the double shields (they mount only a electrostatic), pvc box, the long wires or the mounting hardware. So it seems that the error is mine to think that the earth wire is something normal  in a transformer :huh: …

For the reference, the price of the hv trafo with these specs is 60.53€/each and 28.32 for the small torid, if I order 10 (or more) units of each size, for less units they add 38€ for each size, the reason is to compensate the time needed to prepare the machine with which they make these products.

I can ask a budget to Torivac for these trafos with all options if there are enough people interested in buying these toroids, although I’m not sure if it will be profitable because the shipping costs in Spain are expensive.

IMG_20170529_093728.JPG

IMG_20170529_093828.JPG

Edited by PICaudio
I don't know why the links to Photobucket of these photos are broke :-(
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On 26-5-2017 at 7:20 AM, Whitigir said:

Any plan for chassis and or transformer group buy ?

I have a quote for the following custom trafos from toroidy.pl

TS250VA PRI: 2x115V SEC: 2x 350V (300mA) 82/137 EUR/pc
TS50VA PRI: 2x115V SEC: 2x 6,3V (3A) (note: with reduced off-load voltage) 26/68 EUR/pc

Ex shipping etc etc of course. They can be delivered in audio grade (first number) and/or SUPREME grade (second number). I am thinking about the HV and two filament trafos in SUPREME grade on top of the chassis behind the tubes and the other three trafos in audio grade inside the chassis.

Still pondering on the LV section; <learning mode>18-0-18 seems way too much for a +-12VDC output. Even 15VAC input (centertapped or dual-winding) seems a bit high for +-12VDC output. I selected the NJM7(8|9)12FA and if I read correctly they have an optimal input of 19V and a minimum of 14,5V. This suggests a trafo of 14VAC sec.</learning mode>

Anyone interested in toroidy trafos (though it may be more economical to order directly from them because of shipping rates)?

Ideas about the LV trafo?

Steef

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8 hours ago, PICaudio said:

...I have some units with a little noises, and all toroids that I've bought to this people have a little bigger voltage differences in the same outputs than these Torivac trafos.

 

Yes, I have one with a little noise and other with a diference (13,2v instead of 12,6v). This is not very serious but it annoys me a little.

I´m interested in buying trafos but I don´t know if I will buy them all at the same time or not.

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