2 PT-2 power transformers on 1 chassis--SR45 amp

howardnair · 24796

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Offline howardnair

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Reply #15 on: January 13, 2014, 10:51:15 AM
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
« Last Edit: January 13, 2014, 01:09:14 PM by howardnair »



Offline 2wo

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Reply #16 on: January 13, 2014, 06:24:33 PM
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 

John S.


Offline howardnair

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Reply #17 on: January 18, 2014, 07:52:05 AM
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
« Last Edit: January 18, 2014, 09:20:38 AM by howardnair »



Offline vetmed

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Reply #18 on: January 18, 2014, 09:10:13 AM
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

Robert Lees


Offline 2wo

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Reply #19 on: January 18, 2014, 09:22:50 AM
OK lets try this. What are your voltages at pin 3 & 6 and pin 9 & 1

John S.


Offline howardnair

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Reply #20 on: January 18, 2014, 09:40:52 AM
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--




Offline 2wo

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Reply #21 on: January 18, 2014, 12:51:43 PM
That string of what looks like diodes, connected to pin 1. What is that?

John S.


Offline howardnair

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Reply #22 on: January 18, 2014, 01:30:03 PM
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



Offline Paul Birkeland

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Reply #23 on: January 18, 2014, 01:58:25 PM
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

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline howardnair

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Reply #24 on: January 18, 2014, 02:04:12 PM
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



Offline howardnair

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Reply #25 on: January 18, 2014, 02:22:25 PM
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



Offline Paul Birkeland

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Reply #26 on: January 18, 2014, 02:36:56 PM
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. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline 2wo

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Reply #27 on: January 18, 2014, 02:44:34 PM
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 

John S.


Offline 2wo

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Reply #28 on: January 18, 2014, 02:47:01 PM
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

John S.


Offline howardnair

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Reply #29 on: January 18, 2014, 03:48:30 PM
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