Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Topic started by: howardnair on January 11, 2014, 02:49:39 AM
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i have 2 pt-2 power trannies on one chassis-on one side/channel i have 450v at b+ on the other side/channel i don't really get a reading-i get fluctuated readings=---this is at b+ and at the plate on the 45 tube-there are no tubes in yet-the odd readings are from ground-yet from b- to b+ i get 450v on both sides -the power trannies are each grounded at a separate point for each - i am beginning to suspect that i need to isolate both trannies from the chassis and find one ground pt for both--a little insight would be greatly appreciated--thanks --howie
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Can you sketch out how you have them hooked up?...John
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this will be a interesting lesson--i had not soldered all the circuits-so completing the ground plane etc-i isolated one transformer completely and then connected its ground to star ground with the other power transformer ground -i have on one channel at b+ 445v--on the other channel a low fluctuating negative reading at b+ but on the b- i have negative 445---this means of course that i am out of phase--so do i connect my transformers in series?????
i have no led's lighting up on my softstart bds--but that is the next problem-
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john i will post a pic in about 2 mins or so--howie
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https://picasaweb.google.com/100635555508988591604/January182014?authkey=Gv1sRgCLKAtazdoePJCw
here is a link to my picasa
i will also attempt to attach a photo in the next reply
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...i have on one channel at b+ 445v--on the other channel a low fluctuating negative reading at b+ but on the b- i have negative 445---this means of course that i am out of phase--...
No, that's not what it means. You need the help of someone who can see what you have in person, and understands more about circuits - there is a limit to how much can be done in forum posts.
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What I can see in your pic. on the input side of the PT-2 you have the hot AC (red) leed connected to '0' unlike the left. This shouldn't really matter, but its the little things...
Next, grounds. Start with safety ground. Each PT-2 shell should make good contact to the chassis through one of the mounting bolts (star washers) then in turn should be connected to the ground pin of the AC input connector.
Power supply ground (common). It looks like this is the top row of pins on the large turret board. The right and left side should not be connected together, at least at this point.
Now disconnect any other grounds that connect the 2 sides together and disconnect the B+ just past the last cap/470k resistor(looks like the red wire?) and check your DC voltage across those resistors.
BTW which side seems to work correctly?...John
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the red lead was a experiment which did not change things--they are both as they should be-the b- or nuetral is not connected from one side to the other-the transformer grounds share the same star ground-i will take the time and isolate them from each other-that may be my issue is that i have the ground terminal on the amp is connected to the chassis-i will change that-looking at the picture the left side is waht works or at least the voltages make sense-thanks howie
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very strange!!!-as of now--power trannies are grounded only at 1 throughbolt-then to power ground--the ground terminal on the transformers now has its own separate set of terminals not connected to the chassis-i still get+ 445v at left side b+-and the fluctuating negative reading on the rt side b+ and at the b- on the right side i get negative 445--i most likely mis-wired something but i cannot seem to find it-at the moment a beer with a scotch chaser is in order-will worry about this later --like tomorow
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You need to get a good night's sleep and look at it fresh tomorrow.
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i received a little help from tre on the audioasylum--it seems i did not understand nor implement the grounding scheme--so i have proper voltages and the amp turns on-the tubes light up --but almost no volume --no leds light on the boards---my pinout for the 6cm7 to the board 4+5 are the heaters---ob on the bd goes to pin 6 -kreg A to pin 3-rca input to pin 7 via a 220 resistor--OA to pin 1-kreg B to pin 9 and pin 8 to ground via a 220 resistor---
-reg goes to ground--
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I am in San Diego if you are anywhere near. I have several amps with similar topology and would be happy to take a look. A schematic would be good. I always make a layout drawing also.
Michael
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ok --have some voltages on the soft start bds--both sides are the same
schematic actual
kregA 4v 0
kregB 0 0 ?
OB 175 354
OA 300 357
IA 441 441
at pin 2 the plate of the 45 tube i have 438--should have 300
at pin 3 iof the 45 tube the grid -i have 0-should be 175v
so i either have the 6cm7 pinout wrong for the softstart or something wrong on the board
there is some confusion as the sr paramour 45 i think used a different transformer-so i am not sure exactly what voltages are correct but doing some backreading things appear to be somewhat inline except of course kregA and OB--the sun is out and it is 45% i am going for a bike ride and get the stink blown off--thanks so much for the help---howie
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michael--i am about as far away as one can get --nantucket island is just about as east in the continental us as one can get--next stop going east is portugal--thanks for your kind offer
howie
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The pin out of the 6CM7 is very different from the 5670. I would start there...John
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john--yes i keep looking at that to make sure i have it right -and the other connections into/out of the softstart--paul joppa suggested someone to look over my shoulder--how i wish -it seems odd but there does not seem to be anyone here on the island with that knowledge -so this being a schematic and not a kit i am a little bit out on a limb-oh well i am going to feed myself and puzzle on this some more==sometimes you can't see for looking--howie
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I can't help much with the soft start board as I don't own one.
What I would do next is see if I could get one of the drivers to work. That might mean disconnecting or bypassing the Shunt reg and just running off B+.
This may well run your 45 beyond spec but for a short proving session, probably be OK...John
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i have been to busy to fool with this --so now i have some time-lets see if this drawing will come out
good!! it does--sooo!!! does anyone see anything wrong --i have removed the softstart boards and cked them out- all seems fine --i did not ck the transistors out of circuit-i will just replace them if i do that --at the moment they seem to ck out-i have all 3 types on the way just in case--i will post a link to some pics-also
https://picasaweb.google.com/100635555508988591604/January182014?authkey=Gv1sRgCLKAtazdoePJCw
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I think PJ was absolutely correct on this one. I have read and re-read your posts and can't understand what you are doing here. Nor is it clear from your photos since I get a dead link. If you were to try posting in English, that is with capital letters and proper punctuation we might have a better chance of comprehending your problem :) BTW hyphens are not really a form of punctuation ;D Your schematic makes no sense to me. You seem to be dealing with voltages of ~ 500 and I am seriously concerned that you will end up hurting yourself since you seem to have only the vaguest idea what you are doing :(
With great sincerity and concern
Robert Lees
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OK lets try this. What are your voltages at pin 3 & 6 and pin 9 & 1
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john -thank you--forgive my bad typing and lack of punctuation-i am a terrible typist-
pin 3 0v
pin 6 438v
pin 9 0
pin1 438v
my link seems to have mind of its own-it says open to anyone with a link-why it changes of its own accord i am not certain--
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That string of what looks like diodes, connected to pin 1. What is that?
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that is the zener diode string for the softstart-which uses a 5670 tube -the change from a 5670 to a 6cm7 may be one of my problems-paul birkeland said it would work just be cognizant of the pin out difference and the difference in the 2 sections of the tube-here is that conversation
http://www.bottlehead.com/smf/index.php/topic,3000.405.html
i sent you a personal message
[email protected]
my email
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that is the zener diode string for the softstart-which uses a 5670 tube -the change from a 5670 to a 6cm7 may be one of my problems-paul birkeland said it would work
I did? You might want to reread the post where I addressed this, I think I spelled it out pretty clearly...
Frankly, I think this project is way, way over your head. If you'd start by just building normal Paramours, then you can at least start with a working amplifier.
http://www.bottlehead.com/smf/index.php/topic,3000.msg49671.html#msg49671 (http://www.bottlehead.com/smf/index.php/topic,3000.msg49671.html#msg49671)
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https://picasaweb.google.com/100635555508988591604/Sr4502?authkey=Gv1sRgCLTk_5qar63CYA
https://picasaweb.google.com/100635555508988591604/Mar202013?authkey=Gv1sRgCO2NkufB29GP9QE
robert-let me ease your mind-the first link is what i am building-the second is 2 different stereomour's that i have built-i have built a reduction and a foreplay- all can be found in the gallery-i have restored several scotts, dynaco's -even a solid state kenwood 9100-no issues to speak of--this thread is a leak-over from the sr45 thread started by debk--this is my first scratch build-my first problem was instituting a proper ground plane-that was solved with help-i am not an expert and just starting to understand circuits and implementing them to a chassis is quite new to me--the softstart uses a 5670 tube-i am attempting to use a 6cm7-any help is appreciated-i have problems with my picasa links -who knows why-i apologize for the bad typing and lack of punctuation-run on sentences-just think of my post as a telegram-howie
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paul-well- yes you did-so long as i was aware that the 6cm7 was 2 different triodes-you should be ok--one for the power supply and one the driver for the 45--and get larger heatsinks-not a exact qoute but it is reply 412--am i in over myhead-yes a little-i have built several bottlehead kits-rebuilt some dynacos -scotts etc--i wanted to do a scratch build-your first has to come eventually-i would love some help--thanks howie
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The best thing you can do is to scratch build Paramours, then install the SR-45.
The SR-45 was never intended to be built from the get-go.
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OK, if the zener string was working the voltage at pin 1 would be less than 300v
Next question, when you built the boards did you use the resistor values intended for the SR-45, or the soft start, they are not interchangeable...John
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I agree with Paul, lets see if we can get this going as a stock amp or at least get the driver stage working...John
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john -thank you-i used the values for the softstart board-so you telling me that they are not interchangeable makes sense as to why the driver does not work-the amp works to a certain extent-when i did have the softstarts installed all the tubes lit up-a tiny bit of sound did come from the speakers--here are the voltages without the driver tubes-b+ to b- 456v
b+ to ground 456v--plate or pin 2 of the 45 456v 0 at the grid of the 45 of course-both sides the same-so what is in this thing-looking at the pics -far left and right 22 uf obbligatto oil cap-the parafeed cap-inboard from that the output transformer-magnequest exo 45s--the big caps below the obbligattos are 100 uf cathode bypass caps--the 4 caps in the middle -220 uf electrolytic 2 for each side-power filter caps-triad c7x 10H-- is topside-the terminal strips with the large resistors right below the filter caps is the power supply -each side is separate-plate chokes are 80h 60 ma. --grid choke is a lundahl 1670 540h 5.3kohm --cathode bypass resistor is 1.5 k--hum pots are 10 ohm with 22 ohm resistors to pins 1 and 4 -those are the building blocks-can and will change whatever is suggested
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i am done for the evening-so running through my head as you and paul talk paramour-it seems much more logical to do just that-paramours -forget the sr45--i have softstart bd, -5670-,-456 b+--the exo 45 is a 5k load-mmmhhh
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and will change whatever is suggested
Build the basic Paramour II circuit. A 47K resistor will work as a plate load instead of the C4S, just to get you going.
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Paul-thank you--I don't have a schematic labeled paramour II- i have the sr 45 paramour schematic-a simple enough change everything is in place -i will lift the zener string from the circuit-and the grid to ground for v2-that leaves one question -the value of the v1 cathode resistor-ie; pin3--the circuit for the sr45 shows a 5.5k resistor and a 2490 resistor in series-intercepted by a 431 sr- a+b simple enough but how much does the 431 figure into this
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Disconnect pin 1 and the zener string, that should isolate the regulator.
On the C4S connected to pin 6, I would remove the 10000uf cap and 33k resistor. Now see if the LEDs light and check the voltage at pin 3. Try adjusting the pot to see if you can get ~3-8v or so at pin 3...John
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Hello
The 2490 ohm resister in series with the 5.5K resister sets the operating point of the shunt regulator. The 431 chip has a voltage reference of 2.5 volts. So the 2490 ohm resister forms a voltage divider with the 5.5K resister so the 431 chip holds the regulator at 550 volts in this case. I would guess this is more voltage than you want for a 45 amp. And of course if your power supply won't produce at least 550 volts the shunt regulator will not work at all.
One more thing I learned the hard way, the anode of the 431 chip must go to ground. Not the cathode as you would think if you did not read the data sheet carefully enough.
Michael
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Hello
The 2490 ohm resister in series with the 5.5K resister sets the operating point of the shunt regulator. The 431 chip has a voltage reference of 2.5 volts. So the 2490 ohm resister forms a voltage divider with the 5.5K resister so the 431 chip holds the regulator at 550 volts in this case.
2.5V across 2.5K -> 8V across 8K.
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john -rt side pin 3 0v pin 6 381v pin 3 at the 45 0v
left side pin 3 4v pin 6 85v pin 3 at the 45 0v
left side driver tube lights up the right side does not
no leds light up--either side-moving the bias resistor on the left side has very little effect
michael -i realized that after i walked away from my post--so i have been going through the sections of morgan jones book on voltage dividers and cathode resistors-the reading is a little more involving when you can apply it to a situation at hand
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On the left side 4v is reasonable, 85v is not, sure its not 185?. But is should play. Might be time to try the 47k resistor ( at least 1W) pin 6 to B+, disconnecting the C4S.
If the right tube is not lighting up there is something wrong with the heater voltage pins 4,5
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Do I disconnect or connect anything else
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WE HAVE MUSIC-direct from b+ via the 47k -on pin3 both sides i have 5.9v-
left side pin 6 185
right side pin 6 177
the rt side 6.3 heaters were not getting voltage--cold joint at transformer-
thank you--john
thank you -paul
now that the amp is viable what will be the next step/s again- thanks -your help was much appreciated
howie
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Next would be to get the C4S for the driver working. The SS is set for 4.3ma, which is probably OK for now. Refer to the SR-45 schematic you can connect a 160k from bD to ground and remove the 300k RLd.
Now, from previous testing it look like the C4S was passing all the B+. This does not bode well for the active components. you can test the LEDs with your meter or a battery, if they light they're OK.
You can test the C4S. leave the 47K in series, Connected from pin 6 to OB and restore the B+ to IB.
If the C4S is working the voltage ACROSS the 47k will only be be a couple of volts. if not replace the transistors and LEDs and try again...John
edit, check the voltage across the 47K before you make changes, so you know were you start
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If the C4S is working the voltage ACROSS the 47k will only be be a couple of volts. if not replace the transistors and LEDs and try again...John
A working CCS feeing 3-4mA of current across a 47K resistor will make more than a few volts.
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john and paul--i will implement the changes and ck the voltages maybe tonite-monday evening i was force fed some nice bourbon from the local distillery--there was some fallout from this-ie; late evening, inebriation-the next day--howie
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Oooooo... I need to be force fed some Bourbon.
I had one last drink from my Woodford Reserve before working on the Crack I am trying to get well this evening.
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Have fun, Paul is right about the voltage across that 47k. As usual I got the decimal wrong...John
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john ----i had to replace 1 led--prior to removing the softstarts and with b+ hooked -OB to 6 and the 47k in circuit also-i get 200v at pin 6--i then removed the bds replaced the one led that did not light- same one both bds-pulled the 2907's and cked them -they are fine so it seems are the 5371 transistors-using a fluke 115-i would replace them just to be sure but have been let down by the mail-you asked to me remove the 300k Rld and install a 160k to ground at bD-i have no bD-i have bB-i have a Rdb which was the 33k across the 10,000uf cap-could you clarify this plz-
Grainger-the bourbon that was forced on me is from a local distillery called Triple 8
the bourbon goes by the name of Nor'Easter--it is a little too easy to drink-I suffer badly when i drink to much
thanks howie
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Sorry I meant bB, the lower end of the 149K R2(b). Looking to break the connection to Kreg.
Adding the 160k from there to ground gives you ~309K, look at the SR Schematic .
Once you think it is working you can replace the 47K with a 1K. If the C4S is working you should see something like 3-5 volts across it and about 200V at pin 6...John
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john - I know this might be a stupid question-do i want to go to ground or -reg on the board
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OK-i took the 160k to ground actually 150k for the moment--with 6.9v at pin 3 --i get 202v at pin6
no led's light up-the music plays-rt now it is just a ipod and some crappy speakers---just so we are on same page-the 47k is still installed-the 10000uf is not reinstalled and neither is the 33k -b+{IA] is not connected nor is zener string
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150k may not be enough, I have not calculated the diode current. Add 15-20k
Then measure the voltage across each led, be careful. Looking for 1-2v. Specify 1.5-1.7v...John
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upped to 168k -pin 3 6.9v and pin 6 204v----0v across the led's--cked them again with battery- still good--
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If you have B+ at LED 1, then something is not connected right. Its only 2 LEDs and 2 resistors. You should be able to figure it out...John
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where did i go?--i didn't --the slowstart bds did go--they do not like to be fooled with -i bought a ccs from k&k audio hooked it to the plate of v1 of the 6cm7 put a 2.k cathode resistor and 33uf cathode bypass cap in and i am using the amp without the second half of the 6cm7 tube -it sounds very good and the voltages are in line-i am considering using a 76 tube -the modifications would be simple- except for my wood top plate even though easily drilled would have to be completely refinished--i know the 76 has been used with a 2A3 but has it been done with a 45-any comments would be appreciated
i would like to thank john and paul for their help even tho it was to no avail--howie
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Yeah, essentially, you're rolling the amp back to being a Paramour-II, which is a good choice.
The 37/76 are nice old driver tubes, nothing wrong there!
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OK, glad you got it going. Just check that you are not running the 45 too hard. we need the value of the cathode resistor, the voltage across it and the the voltage from the plate to ground...John