[dangerbird]

Just aquired a pair. I've locate the bias adustment pots, and I'm assuming that the negative point is the neg speaker terminal,the positive point would be on the tube side of the 10 ohm resistor,,does anyone know what value to adjust the individual tubes to? Also ,it has a master bias adjustment,, any help with that one would be greatly appreciated. Thanks in advance.

[scottnixon]

I think VTL ran a conservative 25ma on each EL34.  That's .25v across each 10ohm

There should be test points/jacks on top.  All these I've seen do not need to go inside to test or adjust
as everything is on the top plate.  Should have 4 black test jacks and a couple red ones.
Trim pots are accessible from top.

[richidoo]

Congrats George, I hope you like them!!

Looks like 275mV, or 27.5mA bias, typical for EL34 type.

Evanna Manley says this Manley 160 is very similar to your VTL.
http://www.manleylabs.com/containerpages/160.html
http://www.manleylabs.com/PDF/HIFI_Manuals/Hi-Fi/MANLEY%20160%20manual.pdf

http://www.stereophile.com/tubepoweramps/1188vtl/

http://www.audiokarma.org/forums/showthread.php?t=144346 (schematic)

I hope this helps a little. Manuals are hard to come by....

[dangerbird]

Well Scott and Richadoo,, thanks for the advice/links,, I can locate the bias adjustmentsm and the master
on the top of the amp), but I cannot locat the bias points, nothing behind the front faceplate, nothing that I can see on top of the amp, so I pulled the bottom off,, made the adjustments,(used the 10 ohm resistor as the bias point)
 and the first el-34 (one on the left) turned red and died,and blew the fuse. I am at my wits end at this point.I guess I'm just stupid, the is nothing like setting the bias feor my old anthem.I'll stop for tonight and try again tomorrow--thanks.

So they queation now is,,where is/sre the bias "points"?????
Thanks gentlemen.

[scottnixon]

All the the ones I've dealt with are like this one:
http://pic5.audiogon.com/i/c/f/1234200239.jpg
Everything is right on top.  If yours is different call VTL

[richidoo]

http://www.vtl.com/pages/bias.html

You don't see any test points on top near the front panel, like in Scott's picture?  Can you post a picture, or email it to me, I will ask my tech friend to look at it.

[dangerbird]

The pots for the adjustment are located on top,I'm having to measure the bias points on the resistor with the bottom panel off.I have located every measurement point except fot the master bias. I can locate the adjustment(master), but am unable to determine where the measurement point is for the master .Thanks for all of your replies/help.

[dangerbird]

Rich,, thanks for the schematic-link-- the master bias has to have an associated resistor,, I'll trace it this morning,and I think that I'll be good to go.My units look similar to the one linked anove,but do not have the exposed caps,or the bias points. Fuse is on the back,rather than the front/top cover,I'm guessing that mine are an earlier production/run,,I'll try to post some pics. Thanks for all of your help gents. aa

[dangerbird]

well I've got all of the individual tubes biased correctly(I hope)I understand the master bias adjustment,but am still unsure where to take the measurment,with that said,,here goes,,I'll report back later,,BTW,,hopefully I'll have better luck when I call VTL on Monday(based upon what I've read here and on other forums).Again,, thanks to all of you who helped---george

[dangerbird]

Update--- sounded kinda garbled/distorted-- so I tweaked the master bias on each amp,,,HEAVEN,,, but I'm still unsure where to make the measurement at(master bias)I'm leaving it alone for now.