WOPL 400 1st time build

gene french

Veteran and General Yakker
Joined
Mar 6, 2022
Messages
5,014
Location
guayabo de bagaces, guanacaste, costa rica....
Tagline
music...the healer of souls...
#83
If you think a output may have a bent pin or they were just very hard to line up, then check them against one of the original sockets. The pins were very blunt on the last amp I built compared to the two prior amps. Several outputs needed a little tweek, then no issues.
Also as Joe says, photos. Joe spots issues right away.
after you install a row...check inside that the pins come through the backplanes...that way you know you did not bend a leg...good luch
 

plex

Journeyman
Joined
Jun 9, 2022
Messages
78
#87
Good morning. I just wanted to ask if the testing in the bringup instructions is required or if I could just redo the power transistors and check each row with the DBT? Because I don't have the resistors required lying around.
 

Gepetto

Administrator
Staff member
Joined
May 15, 2011
Messages
13,473
Location
Sterling, MA
Tagline
Old 'Arn Enthusiast
#89
Good morning. I just wanted to ask if the testing in the bringup instructions is required or if I could just redo the power transistors and check each row with the DBT? Because I don't have the resistors required lying around.
Peter if you have tested with transistors in the bottom row, you are well beyond any steps that require the resistors you reference except to discharge the bulk caps. You do not want to be doing anything with residual charge of more than ~0.5V in each bulk cap or you will damage things.
 

Attachments

Gepetto

Administrator
Staff member
Joined
May 15, 2011
Messages
13,473
Location
Sterling, MA
Tagline
Old 'Arn Enthusiast
#97
Sorry for the large photos. I misplaced my other phone. Will try to take more.
The green wire from the copper input jack plate to the bus bar ground between the 2 bulk caps is not required or desired, should be removed. You should be able to temporarily disconnect the shield connections to PAD 2L and 2R and confirm that there is NO CONNECTION of this copper plate to the chassis or to the bulk cap bus bar ground. After confirming that, reattach the shield connections to PAD 2L and 2R
 

George S.

Veteran and General Yakker
Joined
Feb 18, 2020
Messages
4,539
#98
With my Variac at 120 VAC output, and a 75 watt bulb in the DBT, my bulb showed a deep orange glow, but no where near white light spectrum. Are you seeing white light?
 

Gepetto

Administrator
Staff member
Joined
May 15, 2011
Messages
13,473
Location
Sterling, MA
Tagline
Old 'Arn Enthusiast
#99
With my Variac at 120 VAC output, and a 75 watt bulb in the DBT, my bulb showed a deep orange glow, but no where near white light spectrum. Are you seeing white light?
The glow is mainly from the output bias setting, as you turn the bias down, you will notice the DBT get dimmer.
 

George S.

Veteran and General Yakker
Joined
Feb 18, 2020
Messages
4,539
Additional info on the RCA copper plate. Green wire gets removed, coax shields get soldered to plate or RCA grounding tab. RCAs are insulated from the chassis with the fiber washers, copper plate makes contact with both RCAs and coax shields. Hence, the copper plate RCA assembly floats above chassis ground.
 
Top