trinityamps.com

Trinity Amps Guitar Amp Forum
It is currently Thu Mar 28, 2024 6:56 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 6 posts ] 
Author Message
 Post subject: Huge drop in amp volume
PostPosted: Tue Sep 25, 2018 6:31 pm 
Offline
Novice
Novice
User avatar

Joined: Thu Mar 24, 2016 11:05 am
Posts: 58
TRIWATT's been running great for a year or two, the other day I turned it on the the volume is <10% of what it should be. Took a look at the tubes and V4, one of the 12AX7, was glowing like the sun, compared to V1, V2 and V3 at least.

I swapped out V4, now the tube glow is inline, but it hasn't sorted the volume issue. Thoughts?

_________________
http://amparchives.com


Top
 Profile  
 
PostPosted: Sat Sep 29, 2018 8:18 am 
Offline
Holy Ghost
Holy Ghost
User avatar

Joined: Sun Mar 13, 2005 4:10 pm
Posts: 7519
Location: Canada
First measure all he voltages and compare to before. There may be a clue in that. that's the starting pont.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps


Top
 Profile  
 
PostPosted: Sat Aug 17, 2019 4:13 pm 
Offline
Novice
Novice
User avatar

Joined: Thu Mar 24, 2016 11:05 am
Posts: 58
Finally got around to pulling this amp and checking voltages, something definitely up with V2.


Attachments:
Triwatt_Voltages.jpg
Triwatt_Voltages.jpg [ 156.64 KiB | Viewed 5490 times ]

_________________
http://amparchives.com
Top
 Profile  
 
PostPosted: Sat Aug 17, 2019 4:25 pm 
Offline
Novice
Novice
User avatar

Joined: Thu Mar 24, 2016 11:05 am
Posts: 58
Hrm, replaced V2 and I got my volume back but V2 is glowing maybe a little too much? Here are V2 voltages after the tube swap,

Pin 1 - 186
Pin 2 - 0.007
Pin 3 - 1.3
Pin 4 --
Pin 5 --
Pin 6 - 112
Pin 7 - 0.008
Pin 8 - 1.6

Anything to be worried about with these readings, or the glow? V4 seems quite a bit off (by 70 VDC on Pin 6).


Attachments:
IMG_8697.JPG
IMG_8697.JPG [ 1.26 MiB | Viewed 5489 times ]

_________________
http://amparchives.com
Top
 Profile  
 
PostPosted: Sun Aug 18, 2019 12:23 pm 
Offline
Holy Ghost
Holy Ghost
User avatar

Joined: Sun Mar 13, 2005 4:10 pm
Posts: 7519
Location: Canada
You might want to check the value of the 1K cathode resistor. 1.6V is quite high compared to the sheet.
Touch up the solder joints there. Rest looks OK.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps


Top
 Profile  
 
PostPosted: Sun Aug 18, 2019 2:56 pm 
Offline
Novice
Novice
User avatar

Joined: Thu Mar 24, 2016 11:05 am
Posts: 58
Cathode resistors test fine. Preamp tubes are a mismatch of brands and ages now. Does it make any sense that the 12AT7 on V4 would go, I swapped that out for a 12AX7 and then V2 seemed to have gone, now I've swapped V2 for a 12AX7 and I've got volume back but I'm concerned I'm just going to burn through tubes. I'll give it a run through on the bench here at operating temp and see what happens.

_________________
http://amparchives.com


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 6 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 10 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group