From: "Saved by Internet Explorer 11" Subject: A little help - Traynor YCV50 power section - Page 3 Date: Wed, 7 Oct 2015 15:47:00 -0700 MIME-Version: 1.0 Content-Type: multipart/related; type="text/html"; boundary="----=_NextPart_000_0000_01D10117.67E68050" X-MimeOLE: Produced By Microsoft MimeOLE V6.1.7601.17609 This is a multi-part message in MIME format. ------=_NextPart_000_0000_01D10117.67E68050 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Location: http://www.guitarscanada.com/showthread.php?59432-A-little-help-Traynor-YCV50-power-section/page3
=20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 = =20 = =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20=20 Originally Posted by dtsaudio = A>=20 Originally Posted by dcole = A>Could you guys point me to = where it=20 shows 350mV for bias across 2R resistors?=20 Originally Posted by dtsaudio = A>
The current version = from the=20 website ( http://traynoramps.com/downloads/servman/smycv50b.pdf= A> )=20 shows 75mV across the 2R resistors. With approx. 410V at the = plates, that=20 works out to about 15W dissipation at idle.
Maybe there was a = typo on a=20 different schematic or different cathode resistor values?
On closer look, I think = you=20 guys are looking a 2 separate drawings, the old way was 350mV with = 10R=20 cathode resistors, the newer version specs 75mV across 2R cathode = resistors.
The previous version ("YCV50 Blue") = of the=20 amp, or ( http://traynoramps.com/downloads/servman/smycv50blue.pd= f=20 ) on both page 9 and page 13.=20 Originally Posted by jb welder = A>
It's important to note a few = things:=20
- it's impossible to get any copy of older versions of = service=20 manuals/schematics for any specific YCV amp from Traynor/Yorkville, = even if=20 you "know somebody", they only keep the latest revisions (including=20 "discontinued" models).
- It's likely that unless you have a = new amp=20 or the last revision of a discontinued model, what you look at on = the pdf,=20 will not be exactly the same as the circuit/layout you're working=20 on.
- I suspect there's a few errors
I remember getting one = of these=20 treasures in with serious bias problems due to the auto bias circuit = being=20 totally whacked. I eventually reverted it back to a previous version = without=20 the autobias and it worked perfectly...more importantly, the = customer was=20 happy...
=20 Originally Posted by allthumbs56 = A>
Fenders, Gibsons, Leslies and = Hammonds
http://www.toneonwheels.com/
A few questions, if that's = okay.=20 Originally Posted by nonreverb = A>
Do=20 you have copies of older service manuals, schematics, etc?
Which = version=20 of the amp first came with the auto-balance feature?
How does the = auto-balance feature work?
How do you remove it?
BTW, we = know each=20 other, ...long-time no see, brother.
~ R. Ewald
Back in post #15 dcole posted = a link=20 to a drawing showing the auto-match bias circuit. Complete (older) = service=20 manual is available here: http://www.toomanyhelicopters.com/schems/Traynor_YCV40_= Technical_Manual_w_Schem.pdf=20 It is for the YCV40, version 12.01, Dec.2005.=20 Originally Posted by drwow = A>
Here are the = transistors=20 that sense the cathode current of each output tube and adjust the = bias to=20 each tube independently
Here is how it mates with the output tubes (AS,BS = to=20 cahtodes, A-,B- to grid feeds):
AS and BS sense the current through the cathodes, = Q4 and Q5=20 adjust the bias voltage to the grids of the output tubes = accordingly. You=20 should be able to remove the auto match circuit by changing it over = to the=20 newer version schematic.
The YCS amps have a circuit with a=20 transistor across the bias trimpot. I'm not clear on exactly what = it is=20 doing. The base of the transistor seems to be sensing the screen = grid=20 voltage. The early versions of the YCS claimed to be able to run = either 6L6=20 or EL34's, with the bias auto adjusting. Perhaps that is what this = circuit=20 is doing.
Anyone familiar with this circuit please = comment:
This statement is = incorrect. =20 If you mean they only keep current versions on-line, then yes that = is the=20 case.=20 Originally Posted by drwow = A>
But they certainly have older versions of the schematics. = After=20 all, they have to work on the stuff themselves in their service = dept. And I=20 can say that I have personally received older revision schematics = that are=20 not found online. Perhaps you will need to verify that you are = actually=20 working on a unit (serial #, board revision number etc.), but they = have=20 schematics for older revisions. Within reason of course, there may = not be=20 many versions available for extinct models.
I love being = wrong,=20 it's an opportunity to learn something.=20 Originally Posted by jb welder = A>
After my fourth = attempt at=20 getting information out of Yorkville (w/ serial #, etc.) I got a = reply from=20 Guy Beresford with the correct schematic for the earliest YCV50 = version=20 (V.1).
For those interested:
Here's the bias circuit:
Sorry about those files, they didn't parse full = size,=20 I'll fix it later...
Glad to = year you=20 got it sorted, Guy IS the man. ==20 Originally Posted by drwow = A>
He is indeed...he just = set me=20 up with the Hughes & Kettner Statesman Dual 6L6 schematic...I = wouldn't =20 have touched this amp with a 10 foot pole without it.
=20 Originally Posted by jb welder = A>
Fenders, Gibsons, Leslies and = Hammonds
http://www.toneonwheels.com/
Any headway on the=20 cause?
Never mind,I saw the part about the bad tube in his=20 spares.
Having worked at L&M on lots of Traynors,I = conclude the=20 design is just plain dumb,especially the standby circuitry.I told = that to=20 Guy at Traynor and he spouts of about how brilliant it is. Really? A = mosfet=20 circuit to drop voltage to the power tubes as a standby circuit?An = auto bias=20 circuit? Why I ask?
Too much circuitry inside what should have = been an=20 otherwise simple amp makes for tons of revisions as you can see by = the=20 schematic changes and updates.
Simple is always best in my = book.
t |