Welcome, Guest. Please login or register.
Did you miss your activation email?
November 21, 2024, 01:14:01 PM
Home Help Search Login Register
News: Ceriatone Forums are up and running!!!
 
Guests please register
Note: If you want to help you can donate to keep the forums alive.



Do you want to advertise on this forum ? Send me a private message.

Amplified Parts
+  Ceriatone Forum
|-+  British Style
| |-+  JTM 45, 50
| | |-+  connecting OT primary to V4 and V5		 « previous next »
Pages: [1] Go Down Print
Author Topic: connecting OT primary to V4 and V5  (Read 4326 times)
francois
Newbie
*
Offline Offline

Posts: 7


View Profile
« on: December 18, 2012, 10:33:34 PM »
Hi there,

I built my JTM45 kit but with trannies locally purchased in Europe. The OT is an Hammond 1750Q. Regarding color of wires it seems to be exactly the same as the original Marshall diagramm for primary : Red and White + Black for the common.

Now i have to connect red and white to pin 3 of the V4 and V5. I don't know which one is V4 and which one is V5 ( i guess that is the one closer to PT and V4 the one closer to preamps.

I read on another forum it was important to connect in the good way :
Quote
Red goes to pin 3 V4 while white goes to pin 3 V5. If when you power the amp on it turns into the screaming banshee of death, reverse the wires going to pin 5 of each power valve.
So, how to connect?  I would prefer to have the amp working at the 1st  power on  Wink
Logged
T Wilcox
Sr. Member
****
Offline Offline

Gender: Male
Posts: 399



View Profile
« Reply #1 on: December 19, 2012, 01:27:04 AM »
Hey francois

On most of the trannies I've used ( Classic Tone usually ) the OT primaries are red and blue and the CT is white.
Hammond may use different colors but you confirm this on your spec sheet.

1st On most all tube amps V1 is the smaller pre-amp tube furthest from the larger output tubes. From V1 the next tube is V2 and the next is V3 and so on....
On the JTM 45 you got
V1 - 12ax7
V2 - 12ax7
V3 - 12ax7  Phase Inverter
V4 - KT66
V5 - KT66
V6 - GZ34 rectifier
Hope that makes sense..

Anyways, Once you figure out which 2 wires are you OT primaries they will land at both V4 and V5 pin 3. You have a 50% chance of having them reversed ( so leave enough wire length). If they are reversed you will know immediately when you power the amp up, it will be the loudest most annoying squealing sound you have ever heard! No worries just desolder and swap the 2 wires and as long as every thing else is wired correctly your amp will be working.

Hope this answered your question

Todd
Logged
Plexi bass 1986 ( build #6 )
Ceriatone Ultra Champ ( build #5 )
TW Express clone ( build #4 )
Ceriatone HRM MK2 ( build #3 )
Ceriatone 2550  ( Build #2 )
Ceriatone OTS FM50 Modern Eagle Mod (Build #1)
EBMM Steve Morse original
50th anniv American Strat
francois
Newbie
*
Offline Offline

Posts: 7


View Profile
« Reply #2 on: December 19, 2012, 11:29:41 AM »
Hi !

Thank you very much for the precise answer !
Yes, i confirm the color on spec sheet from Hammond

Quote
You have a 50% chance of having them reversed ( so leave enough wire length). If they are reversed you will know immediately when you power the amp up, it will be the loudest most annoying squealing sound you have ever heard
!

OK. I have already anticipated the wire length to reverse in case of . But, with my level in guitar playing , i am 100% sure to produce the most annoying squealing sound ever heard !  Grin
Logged
Pages: [1] Go Up Print 
« previous next »
Jump to:  


Login with username, password and session length

Powered by MySQL Powered by PHP Powered by SMF 1.1.12 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!

CeriaTone Forum is not afiliated with Ceriatone Amplifications. The CeriaTone and name, logo and related trademarks and service marks, owned by CeriaTone. , are registered and/or used in the U.S. and many foreign countries. All other trademarks, service marks, and trade names referenced in this site are the property of their respective owners.