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Let the magic smoke out of R30

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E

Evenharmonics

Banned
Joined 2007
Steven-H said:
1) w/ no tubes in,
B+ = 0v
B- = 0v. R6 is bad
Output tube filament supply left =4.96v , right =4.96v

2) w/ rectifier tube in,
B+ =474v
B- = 0v. R6 is bad
Output tube grid to ground left = 0v , right =0v

3) w/ rectifier tube and input tubes in,
B+ =474v
B- =0
Input tube plate to ground left =1.2v , right =1.2v

4) w/ all tubes in and set the output tube bias,
B+ =474v
B- =0
Input tube plate to ground left = 1.2v, right = 1.2v
Click to expand...
Looks like the voltages indicated something was wrong from the first step. You want to take care of that before going any further otherwise you will damage other parts. I followed step by step exactly as written on TSE checkout process. Step 1 should show negative voltage from both B+ and B-.
 
S

Steven-H

Member
Joined 2007
Well to close this out.....

The amp is alive and well, my issues were due to using an incorrect BOM. Lessons learned:

1 - always do your own BOM and check it twice.
2 - U1 requires SIGNIFICANT heat sinking. Use heat transfer epoxy to assure good bonding.
3 - Use a 5w value for R5
4 - It certainly was worth the drama.
 
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