Pin 3 is the anode and pin 4 the screen grid. You should see close to 500v DC on the anode and a high voltage as well on the screen grid. Is your meter still set to AC voltage when measuring these pins? I assume bias sets up OK so may be a measurement error.
+8
cci1492
vtshopdog
arledgsc
corndog71
Peter W.
GP49
j beede
peterh
12 posters
Dynaco MK3 Low output!!!!
arledgsc- Posts : 503
Join date : 2012-11-30
PeppaPig- Posts : 24
Join date : 2017-06-18
Location : West Dakota
arledgsc wrote:Pin 3 is the anode and pin 4 the screen grid. You should see close to 500v DC on the anode and a high voltage as well on the screen grid. Is your meter still set to AC voltage when measuring these pins? I assume bias sets up OK so may be a measurement error.
It might have. I ill check tomorrow to confirm. I should note that the bias is set to 1.4v dc I used a 10 ohm 2% 10w resistor on the bias. The tubes in both amps light up and get hot equally. Both pass sound because i tested it with one and then the other and still got sound both times.
Could the low output be just the preamp tube and the kt88's doing nothing?
pichacker- Posts : 103
Join date : 2016-08-01
Age : 60
Location : Near to London - UK
Bob, can you post a good quality photograph of the faulty amplifier? A picture paints a thousand words.
PeppaPig- Posts : 24
Join date : 2017-06-18
Location : West Dakota
Yes I can I'll do that tonight
Bob Latino- Admin
- Posts : 3274
Join date : 2008-11-26
Location : Massachusetts
BobtheBuilder wrote:Yes I can I'll do that tonight
Since Bob is a new member, he will not be able to post a photo or link until this coming Sunday June 25. Bob, on Sunday the forum software will allow you to post photos or a link to a gallery of photos of your amp. This is done so that a "member" cannot join and immediately post spam or porno links on our forum. Believe me, this has happened before. Note > The forum software here cannot "host" a photo. You must host the photo somewhere else on the internet and then link to it. Read the sticky above on how to post a photo.
Bob
PeppaPig- Posts : 24
Join date : 2017-06-18
Location : West Dakota
Okay fair enough.
PeppaPig- Posts : 24
Join date : 2017-06-18
Location : West Dakota
All reference is to ground pin 3 is 471v dc pin 4 is 475v dc pin 5 is -52v dc pin 6 is -52v dc pin 7 is 3.8v dc pin 2 is 3.9v dc. It is the same with both kt88s.
PeppaPig- Posts : 24
Join date : 2017-06-18
Location : West Dakota
Great news it's fixed! Thanks you to everyone who helped it was a resistor on the transformer output was burned up. It was new but I hit it with the soldering iron and destroyed it I thing.
BNR_1- Posts : 111
Join date : 2013-06-11
I am glad you figured out the problem. But I am a bit disappointed. This post was like a suspense tv program....waiting for The Who did it. Now it is all over.
arledgsc- Posts : 503
Join date : 2012-11-30
Congrats and good job!
PeppaPig- Posts : 24
Join date : 2017-06-18
Location : West Dakota
Yah I know. Even I was hoping for something better, like the amp was cursed by a pirate and I was damned to sail the seven seas or the metal they made it from was radioactive and I was turning into the hulk.
Lesson hear is be careful where you poke it.
Lesson hear is be careful where you poke it.