WOPL 400 Down Under

[WOPL Sniffer]

Yeah, you don't want shorted "Bits"...............

 

[MarkWComer]

I’m surprised that after my long absence there were any unWOPLed PL amps left on Earth…

 

[Timmienator]

I didn't get around to powering up for testing but I did open up the unit with DC in one channel and it has some extra bits inside I have not seen before.
Does anyone have any ideas what it is?

 

[gene french]

I didn't get around to powering up for testing but I did open up the unit with DC in one channel and it has some extra bits inside I have not seen before.
Does anyone have any ideas what it is?

balanced inputs???

 

[gene french]

once i had dc on output...that proved to be q8 (2n1304) was bad...if the fuses are good and outputs check out ok ..that transistor according to joe ..will rain on your parade....

 

[Timmienator]

Gene you are correct re the balanced inputs however both units have that yet only one has the extra circuit board and the other has nothing else but the input plugs.
I was wondering if the circuit could have anything to do with the issue the amp has with DC

 

[Timmienator]

Ok just had another look at it, for info left channel is putting out DC.

Left channel
Q8 marked 2n1304
Q9 marked 2n1305

Right channel
Q8 marked 2n1308
Q9 marked 2n1307

Does this sound right?

Also there is a resistor in parallel to d8 on both channels
Left is 3.8k and right is 1.5k.
Right channel also has no heatsinks on q7 and q10.
Everything else looks factory or has been done by someone proficient with an iron.
Board is a 14b.

 

[Timmienator]

Ok I just fired it up with some power.
DBT in the line.
Bright then dimmed so ok.

Tested rail voltage it was 67.4 on both positive and negative.

Checked DC offset and still had rail voltage on left channel. Right side is 4.5mv.

Then checked bias
Left channel was 388mv and didn't change with movement of R20.
Right channel was 355mv and did change with movement of R20.

I also looked closer at the PCB integrated into the input, it has an IC on it labelled LF353. It also has a feed from both the POS and NEG rail at the caps. I know nothing about balanced inputs so wondered if that could cause any problems I am currently having.

Back plane also felt hot and I have never experienced that with my 4 fin ever. My assumption is that shorted outputs are the culprit with that symptom.

So here I asking if the brains trust can help?

 

[laatsch55]

Normal rail voltage is +/- 80. So something is pulling down rail voltage. Ok..DBT in line. Remove the balanced input assembly. Eliminate all wires going to it from their source EXCEPT the plus/minus signal feeds to the boards. Install rca Jack's. Remove all outputs on bad channel and do diode check.
In circuit diode check the semiconductors on bad channel. Nothing serious, just check for opens or shorts for now.

 

[Timmienator]

Lee
My plan now is to moderately restore one of these for selling. By moderate I mean
Upgrade PS caps
Replace electrolytics on control board
C6 value change and diode addition
Q1,Q2, Q3 and Q4 replacement
Bridge upgrade with WO snubber kit
New MJ21196 outputs
WO LED upgrade board
Don's DCP

Just trying to figure out if this control board needs more work to be usable.

The other control board is a PL14a I believe (marked pl14 on board) but that has seen way better days by its looks.
What are your thoughts?

 

[laatsch55]

Looks like a good plan tome.

 

[laatsch55]

Ok just had another look at it, for info left channel is putting out DC.

Left channel
Q8 marked 2n1304
Q9 marked 2n1305

Right channel
Q8 marked 2n1308
Q9 marked 2n1307

Does this sound right?

Also there is a resistor in parallel to d8 on both channels
Left is 3.8k and right is 1.5k.
Right channel also has no heatsinks on q7 and q10.
Everything else looks factory or has been done by someone proficient with an iron.
Board is a 14b.

The resistors In parallel with D8. That's what the measure or that's what they are marked at. If the 1307 and 1308 measure the same as the 1304 and 05 , maybe they're ok. If you cant find any 1304 or 1305's I can send ya some.

 

[Timmienator]

Ok
Can I test with those wires you mentioned taped off?
I'll get some sili pads tomorrow for some of the old outputs from my 4 fin and see what happens.

 

[gene french]

here is a pic of a 14b board for your reference...i have a few that i picked up on ebay and a fellow member provided one for me in my desperation.
you will notice the 1304s are missing...i do have spare 1304s but i have not needed to install yet...your board has seen better days..kinda hard to trust it...after the mods, mismatched outputs, mismatched transistors...might be easier to swap out....

 

[Timmienator]

Also would I need to replace q8,q9 on both channels?

 

[gene french]

a pic of a 14a...
i got my 1304 replacements from joe...just chunk in a few with your woad order...

 

[gene french]

Lee
My plan now is to moderately restore one of these for selling. By moderate I mean
Upgrade PS caps
Replace electrolytics on control board
C6 value change and diode addition
Q1,Q2, Q3 and Q4 replacement
Bridge upgrade with WO snubber kit
New MJ21196 outputs
WO LED upgrade board
Don's DCP

Just trying to figure out if this control board needs more work to be usable.

The other control board is a PL14a I believe (marked pl14 on board) but that has seen way better days by its looks.
What are your thoughts?

my pl14a says pl14a...

 

[gene french]

i added fins to the 4 fin i converted to wopl and added fins to the 4 fin i left stock...i did add ps cap upgrade, led upgrades, cap kits, and dcp boards to all...i think i want one more 400...

 

[WOPL Sniffer]

I didn't get around to powering up for testing but I did open up the unit with DC in one channel and it has some extra bits inside I have not seen before.
Does anyone have any ideas what it is?

It's the extra "Bit's"

 

[laatsch55]

Also would I need to replace q8,q9 on both channels?

If they test bad yes..