PeeCeeBee V4H GB

[Kokanee]

Thanks bullittstang, I was having a senior moment when I mounted Q9 and Q10 on the top of the pcb. Should be easy enough to de-solder and mount underneath as most builders have done. I need to be more attentive.

Is a little thermal grease or a keratherm type pad recommended with the plastic body or just bolted to the heatsink naked ?

Thanks again,

 

[bullittstang]

plastic body - light smear of thermal grease only.

 

[Kokanee]

Thanks bullittstang. As it happens, I installed the BD139/BD140 combination, even though I asked about the low hfe and the higher voltage rails (My memory is really bad, I must learn to write things down and make lists). So it is a good thing I had to remove them. I have some MGE340/MGE350 coming in, so I can replace the BD139/140 with some higher hfe devices.

Also, can the Mfets be mounted on the heatsink without a gap between the bottom of pcb and the top of the Mfets. I hope so, because I soldered the Mfets on to the pcb while doing all the Rev1 and Rev 2 mods and it would be a real pain to unsolder all that work to raise the pcb up a bit.

I have some heatsink idea's and questions that I will leave for another time.

Thanks for the help

 

[bullittstang]

Not sure you mean Hfe, but the Voltage rating as to why you are changing from BD139/140 to MJE340/350s (80V vs. 300V) they both have similar Hfe. You can also use KSA3503/A1381s - that's what I'm using.

EDIT: These boards are designed to have the outputs right up against the board, I believe the holes aren't large enough to fit a screw through, so you have no other option.

 

[Kokanee]

I also have 2 of the KS3503DS with a hfe of 78 and I have lots of SA1381's with hfe of 110. That's about as close as I can get for now with that combo.

** I also have some MJE350 that have an hfe of 78, so could I use these with the KS3503 rather than the SA1381's ?

I thought to screw down the Mfets and then have a spacer between the top of Mfet and the pcb, so just a bit of the leg through the hole to solder. Ventilation purpose only. Glad to hear that I will not have to de-solder anything, just mount to heatsink.
Looking forward to answer on **

Thanks for the help,

 

[bullittstang]

I would not mix them up, use the complementary transistors (either MJE340/350 or KSC3503/A1381). You have trim pots for VAS, Offset and Bias - so not critical that you match them at all, If you want to match - I would match Vbe, then just make sure Hfe is "in the ballpark" and you will be good.

 

[Kokanee]

Thank you for this info. I have some MJE340's to be delivered, so once they arrive, I will see if I can get a close match with the 350's, or, I will go with the 3503/1381 combo.

I know I had matching on my mind when I installed Q1 and Q2, but I honestly cannot remember whether I matched them before soldering in place. Hopefully no SQ problems and only mV offset variance. Not sure if I want to de-solder these pairs to measure hfe.

Regards

 

[Kokanee]

Hello Builders,

I have been working through the thread and looking at pictures to try to determine whether "plastic shoulder washers" are needed for the MFets Q11, Q12, Q13, Q14. I could not determine if they are needed or not. Can the naked bolt just be used through thru MFet hole ?
Please help with this,
Regards

 

[bullittstang]

I did not use any washers between the board and outputs - straight through with a cap-head socket bolt to the heatsink.

 

[Kokanee]

@bullittstang thanks for the quick reply. I think I saw some people use a small metal washer to distribute some pressure.

 

[bullittstang]

Not necessary since the boards are 2.0mm thick - you aren't going to get any additional or even out the pressure by adding a 0.3mm thick washer. Only reason to add a washer is to make sure the head of the bolt doesn't pull through the board.

 

[marian1208]

Hello Shaan. I need 13 PCBs PeeCeeBee V4H for a home theater combiner. With shipping to Poland.

 

[cejas99]

Hi Shaan.
In 2019, I bought 6 peeceebee V4H Revision 1 boards from you and I need you to please share the file for setup revision 1. Thank you so much

 

[shaan]

Hi cejas.

Here it is Rev1 mod guide post link.

 

[cejas99]

Thank you Shaan

 

[patriz]

Hi Shaan, what should be the voltages on the power mosfet gates? I'm having problems with my build,

 

[Kokanee]

Hello shaan and fellow builders,
Due to the price increases all over the world, I am proposing to minimize my planned dual mono build (2 trans, 2 psu, etc ) to a single transformer, one psu board, and 2 x V4H amp boards. Is there any downside to building the minimized version. Thanks for your comments and idea's.

MM

 

[bullittstang]

I don't think you will hear any difference, especially if you don't have super-high end pre amp driving it. I bought some defective boards and repaired them, used a repurposed +/-65V transformer with supply board and think it sounds really good. I then changed to a SMPS with +/-65V and didn't notice any difference. YMMV, because I don't have the best hearing after years of enjoying rock music at pretty loud levels.
I think you will be very happy both with the V4H amps and a single PSU unit in your build.

 

[Kokanee]

Thanks bullittstang for your comments and building experience. I am doing the same minimizing with the Alpha Nirvana build. Now I will have an extra PeeCeeBee psu and SLB dual rail psu ready built for some other builds that may pop up.
MM

 

[shaan]

Hi Shaan, what should be the voltages on the power mosfet gates? I'm having problems with my build,

Hi Patriz.

It should be very close to 0V relative to PSU ground at zero bias, after biasing it should be about 0.2-0.4V. Can you please describe the problem?

Hello shaan and fellow builders,
Due to the price increases all over the world, I am proposing to minimize my planned dual mono build (2 trans, 2 psu, etc ) to a single transformer, one psu board, and 2 x V4H amp boards. Is there any downside to building the minimized version. Thanks for your comments and idea's.

MM

Shared PSU/trafo is fine. Other than a very small decrease in both headroom and crosstalk performance, nothing is affected. After @bullittstang , you will hardly notice any changes.