DIY :Pass F5 Turbo V2 Joshua & Ali's Documented Build

[omishra]

The Rectifier Board has been populated:

I have used a 5 mm spacer below the board. The feet of the MUR3020WTs are bent in such a way that when the assembly is placed on a flat surface, the metallic back surface of all the MURs touch the flat surface. Bending at equal distance is critical so that all of them are of uniform height.

You made little hurry in soldering those diodes, should have waited. First drill on mounting surface for diodes, fit them loosely along with thermal pad/paste then place PCB with diodes pins inside hole. Adjust them nicely in single line and then tighten diodes to flat surface. Finally you solder them.
Anyway you have take care now. Make sure to follow this for Amp Board MOSFETs.
Also there are big bulbs of solder, please make it less and cleaner. Because some places - there are gaps around them. Clean the pads before soldering, it seems silver immersion has blackened.

@Om & Sachin : need your kind help with some clarifications

1) In the Rectifier board, are IN AC1 & IN AC2 the inputs for the 24 V AC out of the transformer? Is IN AC1 live and IN AC2 neutral? Or are they interchangeable?

Yes definitely! They are for secondary wires from transformer, interchangeable among one pair and not for live mains.

2) On the power amplifier board, I see three points marked as SPK OUT, see the areas circled in red. They look like the same point (at least by looking at the trace on the circuit board). Does this mean we have three points from where we can tap speaker out? From the PCB trace, the two holes inside each red circle are on the same PCB trace. Meaning all three circled points seem to be one and the same. Where do I tap the negative out for the speaker?

Choose any one of them you like which is nearest to output post with smaller wire.
I choose speaker GND return path from pad near P3, near central speaker output position but away from input ground.

3) The Rectifier Board mentions 16 numbers of MUR3060WT and the power amp board mentions MUR3020WT (8 nos). But I got only MUR3020WTs (24 of them). Are these interchangeable? I looked closely after completing soldering the Rectifier Board and made this discovery. I hope they are interchangeable

They are same, use wherever marked as MUR3020xx.

4) Power Supply Wiring

Should the wiring be: IEC socket --> fuse --> soft start board --> transformer --> Rectifier Board --> PS board (the one with the capacitor bank) --> then to the power amp boards?

Correct!

5) The kit includes two 3510 Bridge Rectifiers along with one 10A NTC thermistor. Where do I use the second 3510?

This is for 2 mono blocks sharing single cab and mains wire and different secondary wires.
Both are for making 2 ground isolators to be connected from each PS ground to mains earth ground. Thus you keep grounds of both Amp boards separate. So avoid loop through source RCA ground as well as both channel are safely grounded to earth.

Edit - Adding one more question: on the power amp board, is it advisable to couple the MUR3020WTs to the main heatsink just like the power transistors? Or should we use a small independent heatsink for each MUR3020?

No don't couple them to main heatsink, try to keep them cool possible. Separate small heatsink or no heatsink will do. On more temperature, diodes conduct at early, Vf is less than standard 25 deg C.

 

[quad]

Edit: looks like Om answered this ahead of me

1) In the Rectifier board, are IN AC1 & IN AC2 the inputs for the 24 V AC out of the transformer? Is IN AC1 live and IN AC2 neutral? Or are they interchangeable?

Guessing - these should we the two ends of a secondary winding of
the transformer. No "live" and 'neutral" - don't connect to mains!

3) The Rectifier Board mentions 16 numbers of MUR3060WT and the power amp board mentions MUR3020WT (8 nos). But I got only MUR3020WTs (24 of them). Are these interchangeable? I looked closely after completing soldering the Rectifier Board and made this discovery. I hope they are interchangeable

Took a look at the specs. For this purpose, the MUR3020WT look adequate.
It has a lower reverse voltage spec, but faster recovery time. Some useful info
here on these specs -

Choosing diode Vrrm in a power supply - diyAudio

5) The kit includes two 3510 Bridge Rectifiers along with one 10A NTC thermistor. Where do I use the second 3510?

Ground isolator info posted by Om -

F5 Turbo Builders Thread - Page 141 - diyAudio

 

[jls001]

You made little hurry in soldering those diodes, should have waited. First drill on mounting surface for diodes, fit them loosely along with thermal pad/paste then place PCB with diodes pins inside hole. Adjust them nicely in single line and then tighten diodes to flat surface. Finally you solder them.
Anyway you have take care now. Make sure to follow this for Amp Board MOSFETs.

Magma will take care of it. LoL :lol::lol::lol:

Seriously, I did think about that. Magma lives some 20 kms away and he has to do the drilling part. It becomes a bit tough to pass the unfinished board back and forth. In any case, since the rectifiers are now fixed, he has to mark the drilling point, drill the exact hole on his bench drill and tap the screw threads. I think it can be done. And despite your warning, I guess I will have to do the same for the power MOSFETs too. Careful drilling will be required, of course.

Choose any one of them you like which is nearest to output post with smaller wire.
I choose speaker GND return path from pad near P3, near central speaker output position but away from input ground.

I still have doubt here: see the close-up below:

So can I use SPK OUT above the P3 in the picture (or SPK OUT to left side in my previous pic, or SPK OUT to right most of the board - as may be convenient) as "live" output of speaker and PGDN GND as "negative" output of speaker?

This is for 2 mono blocks sharing single cab and mains wire and different secondary wires.
Both are for making 2 ground isolators to be connected from each PS ground to mains earth ground. Thus you keep grounds of both Amp boards separate. So avoid loop through source RCA ground as well as both channel are safely grounded to earth.

I will come back with detailed drawings before actually wiring up the earth connections. I am easily confuse by the earthing wiring.

 

[magma]

actaully the mosfet thing

can be done very simply joshua

if you remember this is exactly why i am using the heat spreader

the mosfters will mount on the spreader NOT the sinks

so you have to only carry the spreader back with you

not the heavy large sinks


the spreader gives lots of flexibility

You get me the the boards
we will will see if we can drill and tap there and then

rgds
Ali

 

[omishra]

I still have doubt here: see the close-up below:

So can I use SPK OUT above the P3 in the picture (or SPK OUT to left side in my previous pic, or SPK OUT to right most of the board - as may be convenient) as "live" output of speaker and PGDN GND as "negative" output of speaker?

Yes, any one of SPK OUT could be used as live output and GND as you mentioned. Ground near input 'PGND2' could be used for power Supply ground. It comes between input source ground and output ground. All ground return paths are running towards PGND2 -> PS.

 

[jls001]

the spreader gives lots of flexibility

You get me the the boards
we will will see if we can drill and tap there and then

I will try to complete all soldering work in one-two days and hand over the boards to you for final placement marking and drilling of holes.

 

[jls001]

@Om: some more questions

1) The power amp board has slots for two IRFP9240_V and two IRFP240_V. But the MOSFETs I have are 12P20 and 16N25C. So is 12P20 equivalent to IRFP240_V, and 16N25C equivalent to IRFP240_V?

2) What is the meaning of the numbers written by hand behind the four 12P20 - 1763, 28, 1107, and 1549?

3) Similar numbers behind the 16N25C - 1308, 1468, 137, and 1437

 

[omishra]

@Om: some more questions

1) The power amp board has slots for two IRFP9240_V and two IRFP240_V. But the MOSFETs I have are 12P20 and 16N25C. So is 12P20 equivalent to IRFP240_V, and 16N25C equivalent to IRFP240_V?

IRFP9240_V -> 12P20 P for +ve rail side
IRFP240_V -> 16N25C N for -ve rail side

2) What is the meaning of the numbers written by hand behind the four 12P20 - 1763, 28, 1107, and 1549?

3) Similar numbers behind the 16N25C - 1308, 1468, 137, and 1437

These are serial numbers before sorting and matching. Whatever you got are matched, so now ignore those numbers. These are from DIYA member buzzforb who bought thousands for matching.

 

[magma]

om

1. whats the centre to centre distance of the mosfets
2. what is the thickness of the mosfets ( for purpose of judging the height of screw for tightening ) - the tech specs show 4.8mm is that correct ?
3 thickness of recifiers ( for purpose of judging the height of screw)

since you have designed the PCB

you probably have that centre to centre distance in your records

this distance i assume will be my drilling distance for the mosfets on the heatspreader

Also what size screw is use to tighten the mosfets and rectifiers

the mosfets show a 3.5mm hole
so an M3 screw is it ???

 

[omishra]

I think jls001 can answer this quickly by measuring distance between central pins on PCB, I don't have data right now.

Thickness you assume 5mm with 0.5mm SS washer. M3 is what I used, and suggested by part manufacturer. M4 is thick.

 

[jls001]

I think jls001 can answer this quickly by measuring distance between central pins on PCB, I don't have data right now.

Thickness you assume 5mm with 0.5mm SS washer. M3 is what I used, and suggested by part manufacturer. M4 is thick.

I will measure it.

@magma: M3 screw makes sense as hole itself is 3.5mm. But I don't know what should be the length. We will need to also take into consideration the thickness of the washer (SS? Or GI?).

 

[jls001]

Some pictures:

1) The 12P20 Mosfets all bent and lined up to go into the boards:

2) The 12P25C Mosfets too

3) The MOSFETs in their final places:

4) Top view of the power amp boards

5) Test fitting heat sink for the rectifier diode. Note the temporary "feet". These are 6 + 6 mm tall. The legs of the transistors are bent so that bottom of circuit board to heatsink surface is exactly 12 mm.

6) Another view of the heatsink

 

[jls001]

I will measure it.

Here's the measurements:

 

[omishra]

Looking great! Please double check your each soldering joint.

Also you forgot to tell distance of MOSFET holes from PCB edge. (Might be ~10-12mm)

 

[jls001]

Looking great! Please double check your each soldering joint.

I will do that. I will take some macro shots. In general, I want to err on the generous side when it comes to the quantity of solder. Of course I made sure that it doesn't short the nearby trace. BTW, I carefully scrapped off the light oxidation on the traces before soldering the components. I used a flat screw driver and a 400 grit sand paper.

Also you forgot to tell distance of MOSFET holes from PCB edge. (Might be ~10-12mm)

I will hand over the boards tonight to magma. Though I took the trouble of tracing the outline of circuit board, I think it will be most accurate if he marks the holes from the actual board.

 

[magma]

Joshua's dropped of the boards today so i can tap the spreader and baseplate

Stunningly neat and accurate job i must say
im sure this took a lot of work

New cab shows 6 heatsinks and and extended size
the trafo is one really heavy boy

 

[indialogue]

Looks monstrous!

 

[captrajesh]

Keeping the trafo on one side would result in disproportionate distribution of the weight. Keeping the cap bank and the rectifier boards on either side would be a better option IMO.

 

[omishra]

Great going! :thumbsup:

What do you think about thermal efficiency of area in read circle below.

 

[magma]

thermal efficiency there ( red circle ) - not so good without forced air cooling

however if you note

there are a couple krell designs with sinks like these
since conduction/convection is upwards 70%
its way better than guys who use the fins in horizontal config


but then that is why i am using the copper spreader and 6 sinks instead of 4

i have totally overkilled to compensate for efficiency loss