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Broken HackerNAP Help please?

cutting42

cutting42

Arrived at B4 Hacker Ergo
Hi All

My HackerNAP has given sterling service for many years (10 ish) but sadly a channel disappeared over Christmas. Took it out and had a look and it an initial problem became immediately obvious, R19 (I think) is nicely toasted.

Any ideas what can have failed and what are likely candidates to have been taken out as well.

50771158526_1aa4a171a1_c.jpg
 
Sounds like you got off lightly. The charred pcb will need cleaning back to clean board, even if this means leaving a hole. Epoxy can fill this if you dont fancy leaving the hole for ventilation.
 
david ellwood said:
Sounds like you got off lightly. The charred pcb will need cleaning back to clean board, even if this means leaving a hole. Epoxy can fill this if you dont fancy leaving the hole for ventilation.
Click to expand...

Yeah, it is very burnt, R19 will need to be directly wired to remaining tracks/pins.

I will test a few other components per John Luckins advice on the other thread before I order some stuff.
 
R26 and 27 both open circuit as well. Looked like TR4 had discoloured the cap but it tested fine, might just change TR 4,5 and 6 as I have spares. Need to order the other stuff though.
 
I enjoyed 3 hours of 6 channel active goodness yesterday, first time I had everything finished, tested and bias set with 35-45mV across the 3 new channels
Then THUNK! and silence from the right channel, some of the Vellemans had kicked in and I quickly ripped the power from the amplifiers
2 boards down, the repaired one still good.
Ouch but could have been alot worse, midbass are unobtainable and the 32W/4878 bass drivers are now £540 each from Falcon Acoustics
 
What supply line voltages do you run? Given you’re active it’s unlikely to be load related. Were both failed amps driving the same channel?
Do you stack amps? Maybe heat is the issue?
 
I run the 35v 0 35V R-Cores that we group bought a few years back.
Both of the heatsinks were red hot when I touched them 5 mins after powerdown, they both feed into a velleman each and then a 4 pole speakon.
The volume was set pretty light, no more than a couple watts...

Repaired 1 board today, replaced all these

TR6 - ZTX653
TR7 - MJE15030G
TR8 - MJE15031G
TR9 - MJW21194
TR10 - MJW21194
R26 - .22 R
R27 - .22 R
R19 - 680 R
D3 - 1N4148
D4 - 1N4004
D5 - 1N4004

Removed and checked the bias pot, measured ok and still turns (the one I shorted, you could feel something wrong with screwdiver)
Seems good on the test bench, will give it a more thorough workout tomorrow

The second board needs another look over tomorrow, it seems to measure ok, no dead shorts on OP transisors?

Hopefully the listed parts are all that have died on Cutting42`s casualty
 
juz400 said:
I run the 35v 0 35V R-Cores that we group bought a few years back.
Both of the heatsinks were red hot when I touched them 5 mins after powerdown, they both feed into a velleman each and then a 4 pole speakon.
The volume was set pretty light, no more than a couple watts...

Repaired 1 board today, replaced all these

TR6 - ZTX653
TR7 - MJE15030G
TR8 - MJE15031G
TR9 - MJW21194
TR10 - MJW21194
R26 - .22 R
R27 - .22 R
R19 - 680 R
D3 - 1N4148
D4 - 1N4004
D5 - 1N4004

Removed and checked the bias pot, measured ok and still turns (the one I shorted, you could feel something wrong with screwdiver)
Seems good on the test bench, will give it a more thorough workout tomorrow

The second board needs another look over tomorrow, it seems to measure ok, no dead shorts on OP transisors?

Hopefully the listed parts are all that have died on Cutting42`s casualty
Click to expand...

Yeah, I am replacing all those except the diodes. The parts that actually failed were TR9/10 R19.26,27. I have spares of most of the rest so will switchout as well.
 
All parts replaced and looked great except. However Oh F F S, forgot to drain the caps and was messing about trying to align the op transistors with the heatsink due to the way I built it and a massive spark and blew the new transistors to kingdom come.

Another order to Farnell grumble, moan, sachen frachen.
 
Been there myself but with a preamp psu 40.000uf big spark!

I have discharge resistors on my hackernaps output psu 3.3k 5 watt.

Pete
 
Finished my Hacker this week, it's taken a couple of years on and off. Connected, checked, tested, cased and played with stunt speakers.
Went for 3.2mV Bias, stable and DC offset well <50mV so all good.
Used split earth on the single Velleman with series 12kR resisitors. Speaker returns not connected on the picture below.
https://www.dropbox.com/s/v8248on23mnpgny/P1010229.JPG?dl=0
Looks untidy!
Connected to SL2s, sounds good and stays cool (unless played at stupid volumes). Played for 24hrs or so.

After several recent posts I am wondering how safe I am to continue to use it on the SL2s which are precious?
How often do I need to test the bias and is the Velleman going to protect things?

This is my first power amp diy built from bare boards (no modules) so I am well pleased and thanks to all the contributors on this forum who helped so much.
I'm running the Hacker with my diy Salas pre too, so it is really satisfying.
 
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