Build Thread:PQD2

[Geert Samuel]

Hi there,

I have one. But you should double check before you order with your boards..

This BOM can be used with PCB Grinder’s PQ2 boards?

They are back in stock.. I might order one… but I need to find the BOM

 

[studiosus]

Yes, I build mine with pcb grinders boards. but double check with your boards, i might have forgotten something..

 

[raoul1983]

does anyone know what resistor should be in de DROP? I've ordered a few, but I don't know how to figure out which one should be there.

 

[raoul1983]

figured it out ;-)

But I Have another question.
I've isolated the LM317. But the middle pin is still connected to the bottom plate witch makes contact with ground, is that right? Or shouldn't that be happening? If not, how should I handle the isolation than?

Also when testing with the tubes installed (they glow) I got around 265V before the drop resistor and 0v after the drop and the Drop resistor starts to smoke... Not entirely sure it was smoke from this resistor, but something smoked.

When I do a continue measure, it seems that ground and 12.6v (measure point on the V3 board) is connected, I don't see any solder bridges, what could this be?
Hope you can help me out.

 

[raoul1983]

To be sure I rebought another set of bridge diodes, another LM317 with heatsink (because its shorting to the case even with iso pad)
Also ordered other tubes, I have the EC88 while it should be ECC88 .....!
Hope it will be solved with this all.
If anyone have other ideas, please shoot!

 

[njosnari]

Can anyone share where they found 6.8uf 400v WIMA caps for C59 and C60? What are the best kinds of caps for these? The PCB lists 4.7-10uf? The BOM shared a few posts back lists 400v, is that high of voltage really necessary?

 

[gyraf]

To be sure I rebought another set of bridge diodes, another LM317 with heatsink (because its shorting to the case even with iso pad)

You need not only the iso pad, but also a nylon insert for the hole where the screw goes, to keep it isolated..

 

[raoul1983]

Ahh, of course! Or a nylon screw would also be possible I guess.
Ground and 12.6v shouldn't be connecting right? (it's too obvious, but still..)

 

[raoul1983]

Its working!!!
The power board at least, still waiting on the transformers...

To be curtain I changed the two bridge diodes, and the LM317.
Put in the correct tubes.... ! (mis read the first time)
Had to paralel the resistor, to get a nice 230v.
Tapped power from the 12.6v with a transistor for the power on/off LED

I hope this heat sink is enough. Or is this a no go?

 

[raoul1983]

Finally received the transformers.
left channel works great, right channel doesn't work, There seems to be output but I have to set the levels (after the pq2) very high
Any hints of were to look for the problem?
It doesn't seem to be the in/output xls connections or the connections to the filter board (I think).


Ok, I just swapped the tubes, and now the other channel is working.
so it's probably the tube..
I guess I should just order an other one right?
If there's something else I should check or do, please let me know ;-)

 

[JMan]

just swapped the tubes, and now the other channel is working.
so it's probably the tube..
I guess I should just order an other one right?
If there's something else I should check or do, please let me know ;-)

That sounds pretty straightforward. Sometimes you just end up with a bad tube. It seems to me that you've found the problem.

 

[studiosus]

Sounds good. You might want to order two matched tubes, if you're going to use your eq as a stereo unit.

 

[raoul1983]

I've ordered them matched this time, hope there's no bad one this time, it's a bit more pricey ;-)

 

[joshk34]

Just hoping to get a couple clarifications. The BOM's that have popped up have specified for 330uf 400v caps for the supply. However in Gustav's build guide they seem to be 220uf 400v. Does it matter, or is it related to the specific power supplies used?

Also, I seem to be getting multiple different values for the large high voltage WIMA caps by the tubes? Is there one that works, 4u7f or 6u8f. I see there's a range on the PCB, but just don't know enough yet, to deduce which.

One last thing, is there any specs on the fuse required? I believe the G-Pultec was a 250ma Slo Blow, is that still correct?

Thanks for any help!

 

[joshk34]

Sorry to bump, just need these last pieces and I just have to wire. Any insights to help with my ignorance.

 

[Gustav]

Sorry to bump, just need these last pieces and I just have to wire. Any insights to help with my ignorance.

220 or 330uF caps for the PSU will both be perfectly fine.

And anyting in the range will be fine on the large WIMA cap.

Gustav

 

[joshk34]

Thanks so much!

Got it all wired, flipped it on and the led came on for a split second then went off. Took the measurements, you see and found some continuity between the LM317 and the case, despite the pad and plastic washer. Furthermore, still found continuity even when I picked the LM317 off the case. Im guessing this shorting is causing the readings I’m seeing as well as the LED not to work. I’m struggling to isolate it.

 

[gyraf]

Could be that you measure through the heater to ground? Try measuring without tubes in sockets?