missing leds on one c4s board

[jagmeetbatth]

more

[Paul Birkeland]

If the kit was really old before the HLMP-6000 diodes were installed, they are hygroscopic and can absorb enough moisture over time that damage can occur when soldering.  It may be worth a shot to replace the LEDs on the B side of each C4S board just to rule that out.  Also triple check that the R1 resistors on the high current C4S boards are the correct values.

[jagmeetbatth]

diode range on all 8 leds are same.
can you please mention on photo which r1 resister needed triple check?

[Paul Birkeland]

These.

[jagmeetbatth]

bside 50ohm
a side 37 measuring

[Paul Birkeland]

If you remove the 12AU7 and run the amp with just the 6C45PI tubes, do the OB voltages go up or down?

[jagmeetbatth]

with 12AU7  removed ob voltages stays 330v.

with 12AU7  installed i push power on OB on middle boards starts to rise from 3 to 5 volts and Ob on side two board starts to drop 330 to 245volts and stays at 245v

[Paul Birkeland]

Here are some circled cold solder joints on one of the boards in the amp.  These kinds of soldering issues are a common cause for problems like this when building a kit.

[jagmeetbatth]

i think they are well soldered i checked the continuity.because pads are running underneath it.
anythinng else othher than drysolder joints or bad solodering products.

[Paul Birkeland]

As I mentioned before, the 6C45P tubes are refusing to draw current.  I posted some situations that could occur to cause that to happen.  Bad solder joints would be high on the list.  I would expect that some of those joints that I circled are so poorly flowed that the flux is residing between the through hole and the component lead.

[Doc B.]

I just saved myself $600 yesterday by reflowing about 20 solder pads that looked perfect in the fuel injection control module on my truck, rather than replacing it with new or rebuilt one. Went from no cold start to firing right up on the first try. A reflow very often solves the problem.

[jagmeetbatth]

ok will reflow all three boards

[jagmeetbatth]

reflowed all three boards.connected back again
no change.
what is supposed to bring down pin 20 and 30 to 145 .
is it something in circuit not working

[Paul Birkeland]

what is supposed to bring down pin 20 and 30 to 145 .

When the 6C45P tubes conduct, they will pull that voltage down.  The high voltage at OA/OB on the center PC board and the high voltage on the OB terminals on the high current C4S boards tell us that the 6C45P tubes are unable to do so. 

One thing that is common to both tubes is the ground connection from the attenuator to the ground bus line.  It's certainly possible that the black wire leaving the attenuator isn't well soldered on one end.

[Doc B.]

Since this kit uses the Teflon insulated wire it is also worth checking for breaks in the wire just inside the insulation where the wire might have been nicked when it was stripped. We see that issue every so often.