the Poor Man 660 support thread

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http://www.mif.pg.gda.pl/homepages/frank/sheets/131/6/6900.pdf     4.25 watts    1amp fil

http://www.mif.pg.gda.pl/homepages/frank/sheets/049/7/7044.pdf     4.5watts  8 total for both triodes

http://www.mif.pg.gda.pl/homepages/frank/sheets/127/5/5687.pdf     4.2watts 7.5 watts total

9H pinout

read about the 6900
http://www.vacuumtube.com/issue5.htm

 
I don't have the tube book in front of me, but that must be the one which is listed in the Sams sub book as will work in some 5687 circuits.  Meaning, not all. 
 
Look what is written at the top right of page one of the Link I posted for the 6900, also look at the Gm  of the tube numbers in the links.
 
OK, I'm back.  ;D

I just got my replacement Edcore PT & an IRF840 to replace the IRF820 I had in my PS.
Tonight is the night I should finish this thing up & get it in the rack.
I'll post back the results & whether the HOT Power TX issues go away... hopefully the new TX fixes that.
I'm adding a fan & better heat sinking for the other hot items.

The other test I'm going to do is test the GAIN of the "One Tube" to see how close it is to the 2 New Tung-Sol 5687's (that work correctly in the circuit).
IF the one tube gives the same gain, less heat & same sound... I may just use the single.

I will also test just a single New Tung-Sol 5687 to compare GAIN to the single Philips.

wish me luck.
 
Not so good with the new PT.  :(

I did do the tube test before swapping the PT & the Single tube had the exact same gain & control voltage as using 2.
I measured BOTH the Tung-sol & Philips as the single tube for side chain.
When I tested the "attack time", there was no difference when using 1 or 2 tubes. :-\
This was interesting & confusing...

I sent an email to Rowan concerning the single verses double tube in the sidechain but he hasn't got back to me yet.

The single tube drastically dropped the heat but I'm not sure if it is optimal to run it this way... but I really have no choice because 2 out of the 3 Edcore PT's I tried get VERY hot. All the voltages are perfect too, so I doubt it's anything else causing it, unless I have a weak cap or something pulling to GND. About the 3'd PT I got... lets just say it didn't work as I hoped. ;)

Anyway, I've got other issues with my unit I need to take care of so I may be a few weeks without it.

good luck to all.
 
khstudio said:
I did do the tube test before swapping the PT & the Single tube had the exact same gain & control voltage as using 2.
I measured BOTH the Tung-sol & Philips as the single tube for side chain.
When I tested the "attack time", there was no difference when using 1 or 2 tubes. :-\
This was interesting & confusing...
Click to expand...
Rowan's TC network doesn't need a lot of power to work... It charges a really small cap on attack...
 
I must say I'm really surprised that no one else is having issues with a HOT Edcor Power transformer.

Here are the readings:
Total Heater Current draw = 5.27 amps

15 min = 98 deg F
30 min = 110 deg F
45 min = 115 deg F
60 min = 120 deg F
90 min = 128 deg F
120 min = 135 deg F

At this point the PT is too hot to keep your hand on for more than 5 seconds... if that!  :eek:

Here are the readings with "Just ONE Tube in the Side Chains" - Both Ch:
Total Heater Current draw drops from 5.27 amps to 3.58 amps

15 min = 95 deg F
30 min = 98 deg F
45 min = 103 deg F
60 min = 106 deg F
90 min = 107 deg F
120 min = 107 deg F

MUCH Better, no?
 
Wow, I feel bad for you, Kevin.  This is really a never ending nightmare.  Although you may be getting some use out of the unit in the middle of all this, I hope?

My intuition still tells me something is not right in the unit.  There's too much going on, too many odd things. 

Sorry to hear the Edcor power transformers are acting weird. 

Are you still thinking the explanation for your problem was all in the NOS tubes being bad?  That seemed so amazing and surprising.  I'm just wondering.  Because I have the same tubes (haven't built mine yet, a long story).  Keep us updated, best of luck.
 
I think I'm just unlucky because it's not a difficult circuit & I'm not a total amateur to electronics & building tube gear.

The tubes were definitely my main problem in the beginning... (Philips 5687)
This was proven by first removing one tube in the sidechain & all problems disappeared.
So then I ordered a different brand & set of 5687's (Tung-Sol"s) and it finally worked with 2 tubes.

The only other problem I had from the start was the hot Power TX.
As you can see above, when I pull 2 tubes from the stereo unit, the current draw & heat is drastically reduced.
And since all my voltages are on the money, the only thing I can assume from all this is the Power TX can't handle the current draw... or maybe it can but runs on the edge, who knows. I've never felt a power TX get that hot in all my years of building... like with 100watt Plexi's & Twins, etc...
I down right didn't trust it enough to put it in the rack in my studio... no way.

This is why I got the 3'd PT... lets just say it basically had the same problem as the first 2.

So, I'm pursuing the 1 tube sidechain... it seems way more stable & safe... at least with my unit & the Edcor PT.
 
Nele said:
have you tried using a separate transformer for the heater supply? A 9V/10A monster or something similar?
Click to expand...

I'll eventually test separate transformers for each duty & have one for the heaters but it's 6.3v AC @ 8A
... or if I like it with the one tube side chain, I may just leave it as is.

Just a note to all:
You should always carefully check you Power transformers voltages before installing (& the matching wire color)  ;)
 
khstudio said:
...Just a note to all:
You should always carefully check you Power transformers voltages before installing (& the matching wire color)  ;)
Click to expand...
yes - I never did before but always had luck  :eek: ;) ;) ;) ;D
especially wrong wire colors can hurt ...  :eek: :eek: :eek:
 
Nele said:
have you tried using a separate transformer for the heater supply? A 9V/10A monster or something similar?
Click to expand...

or...power 1 board with the heater secondaries from the edcor and use another toroid for the other board.
That way it does not have to be a monster as Nele suggest...
This is what I'm going to do as well...espacially since I'll be using the regulated suplies.
Sorry for not having read back the whole thread but are you (Kevin) using the slow start heater regulation boards as well?

I stated this before but I would strongly suggest all people who are using the slow start reg boards to read this

http://documents.rs-components.com/EITC/UK/infozone/rectifier_relationships.pdf

As you can see, 6A AC is not enough to power 2 heaters. To get 5,27A regulated DC  you'll need at least 8,5A unregulated AC.

Also Kevin, whats the temperature rise spec of your edcor? 135F might still be within spec but it's hot all right. 107 F seems perfectly ok to mee. What was your room temp when you meassured this?
 
I did read that about the need for at least 8,5A unregulated AC.

I mentioned this to Edcor when I ordered my replacement & they said that there PT would handle it...
to be honest, I don't think they were grasping what I was telling them.  ::)

O yea... the lid was OFF my unit when I measured the Heat! & the AC was on... so probably about 75 deg F in the studio.
I can only imagine what the temp would go up to with the lid ON. :eek:

Gus also suggested that I separate the 2 channels - heaters with separate TX's.

135F might still be within spec but it's hot all right.
Click to expand...
Yea... try putting your hand on it. There's no way in hell I'd trust it running in my studio, especially with the lid on.
I could have bought a house with the money I've invested in here & wouldn't want it to go up in flames.

I wish others with the Edcor PT's would chime in about their PT Temp.
A few people have... but I'm not so sure they're letting it run long enough to really see.
 
khstudio said:
so probably about 75 deg F in the studio.
Click to expand...

Let's see....that's (75F) 24C studio temp. Edcor temp is (135F) 57C so that a temp rise of 33C. Most toroid specs I've seen state a temp rise between 40C and 55C...but still  57C IS hot and with the lid ON your edcor will probably be too hot...

Your edcor is probably running "just" within spec (with lid off...)
 

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