New HT5-R - No Sound!

Discussion - HT-5 amplifiers.
Posts: 1
Joined: Fri Aug 24, 2012 12:00 am
Location: Netherlands

Fri Aug 24, 2012 4:22 pm

New to this forum and thanks to this thread I managed to fix a customers HT-5. Got the same problem here with the amp: R39 totally blown and left some black burned holes in the PCB. I managed to fix the amp by clearing some space around the pads of the mosfet as suggested. Before I did this a tried to desolder some parts for measurement reason. That was not an easy job, the parts fit very tight in the pcb holes. Any suggestions to desolder parts on a PCB like this are very welcome.


Posts: 8
Joined: Sat Aug 18, 2012 12:00 am

Sun Aug 26, 2012 12:18 pm

Hi Fred sorry for the late reply been busy.

I find the best way to desolder the parts from the pcb is to use solder wick which is available from pretty much every where which stocks electronic components. I find it also helps to have a very good soldering iron which gets very hot. A small good tip on the iron also helps to get the parts off the board.

Hope this helps mate and glad you got your amp fixed.

Bs currently have a vacant position for a qa officer the sooner they get it filled the better may be then they will realise they have some major qa issues at the moment.

Cheers Ross.

Posts: 770
Joined: Sat May 01, 2010 12:00 am
Location: Oman

Mon Aug 27, 2012 8:29 am

So far I managed to change the fuse, still no sound. I am waiting for the 12bh7. If swapping the tube doesn't fix the problem then I might be in the same boat as u guys!!

I am not going to be digging that deep in my, I would rather drive for 5 hours and drop @ the tech's.

Although upon snooping around the amp yesterday, haven't noticed any burn marks or blown up maybe I i will get lucky with the tube.

Will keep you posted.

Posts: 1
Joined: Thu Jul 10, 2014 10:04 am
Location: France

Thu Jul 10, 2014 10:09 am

Same here !
I'm a french amp repairman. I got this HT5 from a customer w/ R39 burnt, so I checked the IRF830 (seemed to be OK), replaced R39 (22k/1W) and done some PCB rebuild (burnt tracks), it was OK.
But now, the HT5 is back to my shop with R39 burnt again ... I will llok for a PCB short under TR3 ...
Thanks for the information Rosspj15 and Jaded Faith !

Posts: 1
Joined: Wed Sep 10, 2014 6:08 am

Wed Sep 10, 2014 6:45 am

I just want to thank all previous posters for their hard work. I also bought the HT5 RH and I think mine is same year 2012 model. Mine crackled and died. Sound from emulated out was fine, but you could smelI something was burning inside. I followed the advice here and opened up amp.

R38 was burnt to a crisp. Asked dealer for repair (already passed 1 year guarentee, said it would take around 2 months for repair!). So I figured the repair cannot be that hard.

I bought everything at amazon that you need for repair:
1) 2 x Resistors (R38 & R39)
2) 2 x ... UTF8&psc=1
3) 2 x IRF830 Mosfet transistors ... UTF8&psc=1
4) Drill bit set (For use with hand electric drill) ... UTF8&psc=1
You get the same parts on UK amazon.

I recommend using a good soldering iron with adjustable temperature knob, but anyone with a nice sharp clean tip (40W) will work. Sharp wire cutters, solder sucking pump (helps alot, better than wick).

The reason my R38 kept going was the IRF 830 in front of it as other member pointed out. I also drilled out the sections between prongs of IRF 830, as indicated. Broke a few of the drill bits doing this, but no problem :-) .
Amp is now working again, Yeah.

I thought of replacing my amp, but I jost love the sound too much.
Hope this helps.

One thing I noticed is that these amps are very finicky to the stability of your input power. If there's any dips or flickers in your power supply it will cause noise. I use a voltage stabilizer now and it sounds super.

Best regards,

Posts: 2
Joined: Mon Sep 29, 2014 8:09 am

Mon Sep 29, 2014 8:36 am

This is how I did solve this common blackstar HT-5R problem ! I really don't know how is possible blackstar make this mistake in HT5 series... mosfet's without heatsink ???
Changed: both TR2&TR3 with 8N80 (6N60) on heatsink fitted on the chassis, both 22K resistors, FET J175, A7 diode below R51, R10-10K, 100 ohm smd resistor between J175 and TR2
20140928_135454 [40%].jpg
20140928_135454 [40%].jpg (243.24 KiB) Viewed 15239 times

Posts: 7
Joined: Sun Jun 29, 2014 5:57 am

Mon Sep 29, 2014 4:14 pm

Is this a common problem on all HT5 series amps? Curious as I have a HT5C.

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Posts: 1160
Joined: Wed Jan 29, 2014 7:42 pm
Location: Virginia, United States

Mon Sep 29, 2014 6:41 pm

No. This was specific to a certain batch of HT-5's made in early 2012 due to a defect on the PCB board.

Posts: 1
Joined: Mon Sep 29, 2014 9:08 pm

Mon Sep 29, 2014 9:10 pm


I have a HT-5th anniversary model that has the exact same problem - super quiet gain and silent clean.

These were 2012 models so could this be the same faulty board issue? I guess the board will be the same as the standard HT-5r.


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Posts: 1160
Joined: Wed Jan 29, 2014 7:42 pm
Location: Virginia, United States

Mon Sep 29, 2014 10:46 pm

It could be. The only way to know for sure is to get it on a bench and have it checked.

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