Another WOPL 700B buld

[laatsch55]

No, they do not. The output screws are what hold the heatsinks on....

 

[laatsch55]

Where you have the L & R in magic marker, those two posts should have a plastic or rubber bushing slightly larger than the standoff and slightly longer so you can take an oversize washer and hold the backplanes tight to the chassis to keep them in place while you finish other stuff. You must keep the backplanes tight to the chassis or you will lose the nylon bushings beneath them.

 

[Billboard]

I mounted the bypass switch, but are R54 and C24 required? I guess without the two C24s the amp will be in direct mode all of the time. What about R54, looks like this resistor is normally in the circuit full time.

 

[laatsch55]

was R54 on the RCA input jacks?

 

[Billboard]

yes, on the original, probably still there on the old chassis.

 

[laatsch55]

They are there to take care of transients and static electricity in plugging in the RCA cables. The cap was used in normal mode to strip any DC that may be coming from a pre-amp. If you wish to retain that capability use a 1uf Wima poly or film cap...

 

[Billboard]

how about these?

http://www.parts-express.com/cat/fi...eca:matches(.,"P_Searchable","1")]&PortalID=1

 

[laatsch55]

Nope, these-------- http://www.mouser.com/ProductDetail...=sGAEpiMZZMv1cc3ydrPrFwgzP98AO9idE1x3ZUTCoHM=

 

[Gepetto]

Backplanes in, mechanicals installed.

Is there any mechanical fastener to hold down the backplanes (other than the output screws).

I installed the two upper screws and spacers, I know one is used for chassis ground, do they hold down the backplanes? how?

View attachment 25754 View attachment 25755 View attachment 25756 View attachment 25757

yes in the misc hardware bag that comes with every backplane kit

 

[Billboard]

Nope, these-------- http://www.mouser.com/ProductDetail...=sGAEpiMZZMv1cc3ydrPrFwgzP98AO9idE1x3ZUTCoHM=

Thanks Lee order placed, also ordered a handful of 220K ohm resistors.

 

[Billboard]

yes in the misc hardware bag that comes with every backplane kit

What is the order of the upper hardware. I saw the order on the BOD step 11, but did not see how to attach the boards

6-32 screw
lock wasker
chassis
lock washer
standoff
?
?

 

[laatsch55]

You do not "attach" the board , you hold it in place until the heats inks and outputs are mounted. Then take the washer and "squish" bushing back off.

 

[WOPL Sniffer]

Make sure before you bolt the back planes in, quadruple check the backsides of the boards for overly long leads which may touch the chassis, clean clean clean clean the boards and inspect the solder joints. If you have questionable solder joints, they introduce capacitance, impedance (cracked solder joints, cold joints etc...). You don't want to build an expensive amp that looks like a bomb went off under the hood.

 

[WOPL Sniffer]

It's easier now to do the tedious inspections than to pull them later when the issues "Pop" up.

 

[FredR]

Don't over tighten the TO-3 screws. You can penetrate the silpad and cause a current leakage to the heatsink.

 

[WOPL Sniffer]

and don't leave them to loose, the Transistor will overheat (no heat transfer through the SilPad) and fail. YUP....

 

[laatsch55]

And that's a bad thing.....

 

[WOPL Sniffer]

Si....

 

[Billboard]

OK, all clean and solder joints inspected and trimmed.

Time for wiring, AC up top and DC on the bottom?

Also I bought some snubber? caps (5989-400V.01-F) to go around the bridge rectifier, these are not on the schematic, just want to verify they are recommended.

 

[NavLinear]

OK, all clean and solder joints inspected and trimmed.

Time for wiring, AC up top and DC on the bottom?

Also I bought some snubber? caps (5989-400V.01-F) to go around the bridge rectifier, these are not on the schematic, just want to verify they are recommended.

http://forums.phxaudiotape.com/showthread.php/7075-Parts-Database?highlight=snubber