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PeeCeeBee V4 GB!

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#1,070
Hi Gsusay.

V4 - not available currently
V4H - available - 20USD per PCB
Preamplifier - available - 20USD per PCB
PSU - available - 20USD per pcb
Lateral MOSFET pair for V4H - available - 14USD per pair

edit: I do not sell all components separately. Pre-assembled/ready to use modules are sold only within India, only bare PCBs and MOSFETs are shipped outside of India. BOM for all the above boards are shared in their respective threads. You can assess total cost from them. Links to the threads in my signature.
 
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#1,071
Hi, after assembling my V4 with components I had in hand and modding it to rev2 read that at least first 2 input trasistors should be matched.
So I desoldered all the BC546\556 and measured the Hfe.
For measuring I used 2 device: one Mastech M830B and a chinese multitester like this one.

For the BC 546/556 measuring with DMM I got a very narrow result 300-320 but for the measurements with chinese multimester the measurements are odd. For BC546 I got same reading of HFE 432.

What are you using guys for measuring hfe? I am confused now.

Regarding small value capacitors, now I have some ceramics, would silver mica make more sense or some wima fkp2?
 

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#1,072
atupi said:
Hi, after assembling my V4 with components I had in hand and modding it to rev2 read that at least first 2 input trasistors should be matched.
So I desoldered all the BC546\556 and measured the Hfe.
For measuring I used 2 device: one Mastech M830B and a chinese multitester like this one.

For the BC 546/556 measuring with DMM I got a very narrow result 300-320 but for the measurements with chinese multimester the measurements are odd. For BC546 I got same reading of HFE 432.

What are you using guys for measuring hfe? I am confused now.
Click to expand...

Hi Atupi.

I use Mastech's bottom range MAS830L multimeter to find similar HFE BJTs. I haven't compared its results with other meters but as far as performance of the tested BJTs in the amp goes, I'm satisfied with it.

Regarding small value capacitors, now I have some ceramics, would silver mica make more sense or some wima fkp2?
Click to expand...

If you can afford silver mica then close your eyes and get them in the pF zone. For 100nF caps WIMA polyester types (e.g. MKS4) will be great, polyprops like FKP not necessary but will work nonetheless.
 
#1,073
Happy holidays everyone and a great new year.

Shaan I need your help again. During my work to check the hfe of BC transistors I think I managed to destroy one channel.
First of all I had a solder bridge on Q10 and this lead to get some smoke from R24. I cleaned that bridge, replaced R24 and for few minuted I got few jumping milivolts on speaker output them R24 smoked again. Checked again, nothing looks bad but I get 30V DC on output and R24 gets very fast hot and smoking.

How to start troubleshooting? I would appreciate some help.

All the best,
Adrian
 
#1,074
Hi Adrian.
atupi said:
Happy holidays everyone and a great new year.

Shaan I need your help again. During my work to check the hfe of BC transistors I think I managed to destroy one channel.
First of all I had a solder bridge on Q10 and this lead to get some smoke from R24. I cleaned that bridge, replaced R24 and for few minuted I got few jumping milivolts on speaker output them R24 smoked again. Checked again, nothing looks bad but I get 30V DC on output and R24 gets very fast hot and smoking.

How to start troubleshooting? I would appreciate some help.

All the best,
Adrian
Click to expand...
It seems like the P MOSFET's gate terminal was overloaded by the solder bridge, which would mean the mosfet is dead. Please check continuity between each mosfet terminal and output terminal with power removed, red probe to output terminal. Pin 1 should show open circuit, pin 2 should show short circuit, pin 3 should show a few hundred ohms.
 
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