|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
40.142.185.187
In Reply to: RE: The amp uses 6AS7G power tubes. posted by Ralph on September 11, 2020 at 15:28:13
Thanks for the info and suggestions!
Below are three more images - clearer pictures of the front and back of the transformer and a picture of the circuitry directly below the transformer.
I tested continuity on the primary and various secondaries and it was as expected based on the labeling - had continuity between the 110V and 0V on the primary, and in the expected places on the secondaries both front and back.
Some questions...
To test the voltages, I need some sort of load correct? Would something like a 50 watt incandescent bulb do the trick?
I assume the smaller tubes are rectifiers? Do you know what designation would fit the bill?
Follow Ups:
-
The fact that the 750mA fuse blew when I applied power implies that the transformer is bad I take it.
Can you recommend a replacement? It is unclear to me if the amp circuit "needs" all of the voltage options the current transformer offers.
Well the fact that the leads were disconnected made it a good bet that someone had already sorted out that the transformer had failed.
This is clearly a custom part. So you could have one designed and made up, which would likely run you about $500-$750.00. Or you could use a number of separate transformers to make up the voltages needed. The 6.3V filament winding is probably available as an off-the-shelf toroid. You might be able to find the other voltages except for the B+ for the output tubes- my guess is a custom transformer will be needed for that. Getting all this to fit under that power transformer cover might be a trick. But you might also have room for the smaller transformers (Bias and driver power supply) beneath the chassis.
Thanks Ralph.The current transformer has the following secondaries. Are you able to determine what voltages are used for what purpose?
V1 - 6.3V - filament
V2 - 25V - Bias?
V3 - 60V ?
V4 - -120-0-120V ?
V5 - -260-0-260V ?Clark
I had posted this before and deleted it because the subject line was messed up. Unfortunately, right when I did that, Ralph had replied and that got deleted as well. Fortunately, I got his message in email:
V1 - 6.3V - filament high current, about 25 amps to support all the tubes
V2 - 25V - Bias?
V3 - 60V ?
These two are probably bias supplies, one for the top tubes and one for the
bottom?V4 - -120-0-120V ? Definitely output section, you'll need about 2 amps
V5 - -260-0-260V ? Driver section, probably 50mA will do the job.
Edits: 09/15/20
V1 - 6.3V - filament high current, about 25 amps to support all the tubes
V2 - 25V - Bias?
V3 - 60V ?
These two are probably bias supplies, one for the top tubes and one for the bottom?
V4 - -120-0-120V ? Definitely output section, you'll need about 2 amps
V5 - -260-0-260V ? Driver section, probably 50mA will do the job.
Thanks once again. How exact do the voltages need to be? Could I get away with, say 250-0-250 in place of 260? How about the bias voltages?
250-0-250 would work fine.
The bias probably has to be pretty exact.
Great - I sent an email to the folks at Antique Electronics to see if they had any suggestions for a transformer combo that might fit the bill.
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: