BHK Preamp - not powering up

Hi Folks,

Can someone help me with this issue. I have a BHK Preamp bought Dec 2016- Its signed.
A Yesterday my tubes stopped working so I unplugged the power, turned off the preamp changed the tubes from the old 12AU7 ( RCA) to 12AU7 (Tungsol) - Clean swap.

Apparently the Preamp won’t power up anymore. Any ideas? What could have gone wrong?
There is a red led on the board inside, that does not lit up either. The fuse seems ok - but not sure of that.

Thanks for your help.


The one time mine would not power up it was the fuse. You can check it if you have a volt meter.

If the display is showing a fault wait two minutes after switching power on until you take out of bypass with the front button.

Fuse looking o.k. is no guarantee, swap it anyway.

1 Like

Fuse looking o.k. is no guarantee, swap it anyway.

Right. Similar thing happened to me. Fuse seemed fine but amp (power amp in my case) wouldn’t switch on. Changed the fuse and it worked as normal.

Can I just say, firstly, welcome to the forum. Secondly, you’ve owned a BHK PRE for over 2 years and this is your first post? Maybe there is some truth to the hypothesis that many people only post here when their PS stuff stops working properly.

Hi kc, there is no fault in the display, its dark and not on.

If there doesn’t seem to be any life at all, it’s almost guaranteed to be a fuse. Any chance you can check it with a volt meter?

Come to think of it, I think we just chatted over the phone and we already have some fuses out to you. :smile:
Keep us posted if it works.

I don’t understand how a fuse can seem ok.

Probably the filament is so thin that he can’t see the break with the naked eye. Believe I would have gone and picked one up instead of waiting on the mail for a week.

Also, fuses rarely clear for no reason. Likely something else is amiss.

He had just swapped out the tubes and was powering it back up for the first time after the swap.

I had the fuse in the BHK-pre blow one time - I needed a 20X lupe to see that it was blown. Looked good to my eye.

I blew a fuse once when I plugged the power cord into the back not knowing the switch was in the “on” position, which PSA warns against.

Exactly. I remember I thought I had a problem with one of my Sanders monoblock amplifiers and even support said to return it, but it was only a fuse. Sad having to ship it out with expense and time to only be a $1.00 item go bad.

Well, now you’ve identified a serious problem… you should be buying $1000 fuses for your top notch equipment :grinning:


Haha, exactly, but then who’s gonna give us tech support for that part​:grin::nerd_face:

Hi James thanks, and thanks to everyone. I bought a fuse from local electronics store over the weekend and BHK Pre is back alive again. In the past few years I have switched on and off many tubes- OEM, Telefunken, Mullard , RCA, Tungsol, 7DJ8 and others and never had any issues.

So for those who don’t want to run into this rare fuse blow situation- stock up a few fuses - the Fuse specs are 5 x20 mm slow blow ceramic , 2 amp with gold caps.

1 Like

Awesome, glad to hear it was just a fuse! 2 amp for a 120V unit and 1.6 amp for a 240V unit.

1 Like

Yes and for tubes too. Always keep some spares.

Edit: In fact here’s some great customer service from PS Audio. When I first got my BHK amps I emailed Paul to say I was having difficulty finding spare tubes locally and didn’t know what I’d do if the tubes in my BHKs died. I was just hoping he could recommend some European suppliers. Paul said he would find out.

Couple of days later I get a package from PS Audio (I’m in the UK BTW) - a full set of tubes for my amps courtesy of Paul and PS Audio. They even sent me some gloves and a screwdriver to help put them in.

Also Kevin from Signature Systems the UK distributor sent me a full set of fuses for my amps when I told him that one of mine had died.