My phono stage blows a fuse occasionally?

[kelossus]

In August last year I bought a new Lehmann Silver Cube from Addicted To Audio. When the phono stage arrived it was DOA, they asked me to check the fuse which turned out to be blown. This was a little annoying as it comes with some $80 gold german fuse. Went to Jaycar bought a replace and I only had one channel of audio. After playing around with the cables to see if I had hooked it up wrong suddenly I had no audio at all. Sent the Lehmann back to A2A and they advised the phono stage was working perfectly and there was nothing wrong with it, odd I thought but maybe I had plugged it wrong though I had my doubts. I ended buying another gold fuse to keep it all original and it served me well for the past 6 months.

 

Fast forward to this morning and I was playing around with power cables and I noticed the standby on the phono stage was off. Seems that it has blown another fuse, all I did was unplug it and plug it back in.

 

The phono stage is still under warranty so I should be able to return it A2A. Should I just replace fuse and put this down to an issue with my power or some other error I may have made? Or would you return it A2A again and get them to have a look. I have a feeling all they will do is a put another fuse in it and advise it is working fine. I know it shouldn't be blowing a fuse for no reason and I am hesitant to fork out another $80 for an exotic fuse that is only going to last a few months.

 

 

[metal beat]

Weird.  I have owned many SS and tube phono stages over the last 30 years.  Not one of them has blown a fuse. ( touch wood).

 

IMO, there is something wrong with the unit.   Is it a true 230/240 volt unit?

 

ask them to pay for a new fuse, or give you a new unit.

[Mungbean66]

27 minutes ago, metal beat said:

Ask them to pay for a new fuse, or give you a new unit.

Asking for a replacement fuse isn’t good enough. If the unit keeps blowing fuses this could be indicative of an fault with the unit which should be sent back to the manufacturer for repair. 
I would email the company directly and then send that correspondence to A2A with the preamp so that they are responsible for sending the unit back and having it fixed. 

[Uncle Seth]

Silly question, but just to be clear: Are you using the appropriate fuse-type (e.g. slow-blow)?

 

If so,  and assuming they now accept a return, since you changed the fuse (which is , granted, a user-serviceable part) , send it back for investigation

[kelossus]

Yeah the unit is a 230v Australian model. It has a switch on the back to switch voltages so they are universal.

 

The fuse is definitely the right one. I bought the exact AHP fuse that was originally blown. In between getting the fuse delivered  I used the same rated glass fuse from Jaycar. T 1A 250v.

 

I just have a feeling A2A would just change the fuse send it back and say it's fine. They no longer carry the Lehmann brand so I think getting them to come to the party will be difficult. I am not prepared to drop another $80 on a fuse to have it blow again.

 

Emailing Lehmann and CC'ing in A2A seems like a good idea and worth a try.

 

Ideally I want a replacement unit, ever since the original fault I have been a little put off by the unit. I will add that there is no audible fault when the unit is playing. It sounds great.

[aussievintage]

 

I have seen this before on equipment  where the fuse was actually marginally spec'd for a lower voltage ( e.g. 220V) despite the labelling, and running it on our 250V (sometimes), would cause it to blow the fuse occasionally at turn on.

 

Personally, I would put a slightly higher value fuse in there - maybe 1.5 amp.  It may cure all problems.

[Monkeyboi]

Okay,so just to confirm the correct phono pre-amp.  Tis unit comes with a separate power supply.  Correct?

 

From the user manual the pre-amp uses a four pin connector to supply +/- 18 volts d.c. to the phono pre-amp.

Seeing as it appears to be intermittently blowing fuses I'm wondering if the power connecting cable between the PSU and the phono pre-amp doesn't have an intermittent short circuit in it?

 

This type of fault isn't uncommon.  The flexing of the cable can lead to the insulation cracking or perhaps a single strand of wire is touching inside one of the connectors.

 

It may even be an intermittent short on the power supply either inside the PSU or the phono stage.

 

Any tech worth his salt should be able to diagnose and correct this fault.

 

BTW,I would avoid replacing the fuse with a higher amperage unit. Also check you are using the correct type.  A slow blow fuse acts differently in the circuit to a normal "fast blow" type.  if it is supposed to be fitted with a slow blow fuse but a fast blow type is fitted, the fast blow type may blow due to in-rush currents during switch on. 

 

Cheers,

Alan R.

 

[kelossus]

As per the back of the unit I am using the correct Slow Blow variant.

 

Hesitant to take the unit to a tech locally as it may void my warranty. Do these ceramic audiophile fuses have the tendency to fail when compared to the standard glass fuses? I am wondering if they have a tighter tolerance which may cause an issue.

[Monkeyboi]

1 minute ago, kelossus said:

As per the back of the unit I am using the correct Slow Blow variant.

 

Hesitant to take the unit to a tech locally as it may void my warranty. Do these ceramic audiophile fuses have the tendency to fail when compared to the standard glass fuses? I am wondering if they have a tighter tolerance which may cause an issue.

No. The ceramic fuses are filled with "sand" or a non-conductive filling powder. When the fuse blows, the filling inside prevents an arc trail from depositing a conductive path inside the cylinder which could possibly lead to the fuse not failing correctly.  In the industry, fuses of this construction are known as HRC (high rupture capacity) fuses and come in all shapes and fusing currents.

 

A 1 Amp slow blow  is more than enough to protect a 120W PSU.

 

Cheers,

Alan R.

[aussievintage]

1 hour ago, Monkeyboi said:

I would avoid replacing the fuse with a higher amperage unit.

Only do it after after establishing there is no other fault causing the problem.  OTOH if there is a short or something in the cable, the 1.5 A fuse will also blow.

 

31 minutes ago, Monkeyboi said:

A 1 Amp slow blow  is more than enough to protect a 120W PSU.

You would think so

[The Rock Puppy]

I don't understand the thought processes behind anyone saying try this fix or try that fix ( and I'm not being nasty to anyone, here ), but it isn't a year old and is still under warranty. Send it back and ask for your money back. The business has sold you a faulty item, and I would think the onus is on them to either fix it, or come up with a refund. Keep a note of when it broke, and the circumstances ( moving cables, turning off and on, whatever) under which it was being used at the time, so that if it keeps happening you can show it first occurred within the warranty period. 

If it was out of warranty, I'd not knock anyone for offering a solution, but as it stands it shouldn't be up to you to fix

Emailing Lehman sounds like a good step. Perhaps they will offer a possible list of potential problems/fixes that you could forward on to the retailer.

 

Sorry for the rant, but I've seen similar posts across the forum about new stuff that doesn't work, and people trying a ( quick) fix. It isn't your fault that it's faulty, and it certainly isn't your problem/job to get it fixed.

[aussievintage]

2 minutes ago, The Rock Puppy said:

I don't understand the thought processes behind anyone saying try this fix or try that fix ( and I'm not being nasty to anyone, here ), but it isn't a year old and is still under warranty. Send it back and ask for your money back.

I thought he already  sent it back once and they said it wasn't faulty.   The "thought process" was that the OP seemed to looking for another way around the problem, rather than the hassle of sending it back again, and all the arguments that will involve.

[The Rock Puppy]

Well, he did say that ideally he wanted a replacement unit, and as I said I'm not attacking anyone, but it's not a year old and still under warranty. Sending it back with a blown fuse, and maybe a copy of monkeyboi's first post here, should be enough proof that it needs to be thoroughly checked. 

If you buy a faulty product, fixing the problem isn't the job of the purchaser

One of the few drawbacks of buying online is that you often can't go down to the shop and front the seller involved.

[kelossus]

My initial reason for posting was to get some feedback as to why it kept blowing the fuse. I thought maybe these audiophile fuses have tighter tolerances and maybe the occasional spike in voltage to around 243v may be the issue

 

I was somewhat annoyed that A2A didn't replace the broken fuse with the same AHP one. To be fair I didn't mention it to them so I never expressed my concern with the "inferior" replacement.

 

I think from here I will go to Jaycar and get another fuse to ensure the unit is still working. Then I will open a dialogue with A2A and Lehmann to express my concerns and explore some possible solutions. I have 18 months of warranty left and if there is a minor fault with the unit I want it sorted before the warranty lapses or something major happens.

[andyr]

1 hour ago, kelossus said:

My initial reason for posting was to get some feedback as to why it kept blowing the fuse. I thought maybe these audiophile fuses have tighter tolerances and maybe the occasional spike in voltage to around 243v may be the issue

 

It shouldn't (affect whether the fuse blows or not).

 

Quote

I was somewhat annoyed that A2A didn't replace the broken fuse with the same AHP one.

 

As I would be!  Unless the AHP fuse wasn't the normally supplied fuse?

 

Quote

I want it sorted before the warranty lapses or something major happens.

 

Good luck, K.

 

As I see it, they should firstly swap your unit for a fresh one.  If this new one continues to blow fuses then they should refund you your money, when you return the new Lehmann.

 

The point is - which MB pointed out - is that phono stages are such low powered devices that they should never blow fuses on account of the current being drawn.  Sure, the 'inrush current' when you switch it on is much higher than the steady state current (because of the power transformer and the PS caps charging up) - but as long as the fuse is sized for this initial inrush ... it should not blow from normal operation.

 

I've found you can either use:

• a fast-blo fuse which is 2 - 3 times what the steady-state current draw is, or
• a slo-blo fuse which is just over the steady-state current draw.

 

I used to run a power amp which was just "on the edge"; I used a fast-blo fuse (because to me, that is the more sensible fuse to use!) which, every 3rd or 4th time I turned the amp on, would blow - from the transformer and cap-charging inrush (i didn't turn it off much!).  But I eventually got sick of this and upped the amp rating ... and had no more problem! 

 

Andy

 

 

Edited January 19, 2020 by andyr

[Monkeyboi]

7 hours ago, The Rock Puppy said:

I don't understand the thought processes behind anyone saying try this fix or try that fix ( and I'm not being nasty to anyone, here ), but it isn't a year old and is still under warranty. Send it back and ask for your money back. The business has sold you a faulty item, and I would think the onus is on them to either fix it, or come up with a refund. Keep a note of when it broke, and the circumstances ( moving cables, turning off and on, whatever) under which it was being used at the time, so that if it keeps happening you can show it first occurred within the warranty period. 

If it was out of warranty, I'd not knock anyone for offering a solution, but as it stands it shouldn't be up to you to fix

Emailing Lehman sounds like a good step. Perhaps they will offer a possible list of potential problems/fixes that you could forward on to the retailer.

 

Sorry for the rant, but I've seen similar posts across the forum about new stuff that doesn't work, and people trying a ( quick) fix. It isn't your fault that it's faulty, and it certainly isn't your problem/job to get it fixed.

I agree.  It's a warranty issue.  I think that there may be any number of possible problems as I eluded to in my previous post.

I for one would be interested to find out exactly what the fault is.  The only reason I posted some possible contributing issues is that depending on the technician repairing the fault they might declare it all too hard and simply replace the device holus bolus.  Often the fault is a simple inexpensive fix but the "tech" doing the fault diagnosis is clueless. 

 

Cheers,

Alan R.

 

 

[Bronal]

I agree that an email to Lehmann is worth a try.  Make sure you describe the problem as comprehensively as you can and in simple, straightforward English, to avoid any misunderstandings 'lost in translation'.  Don't forget to provide the serial number and date of purchase (a copy of the receipt would also be good). Copy the email, and any reply, to A2A, so you are not seen to be going behind their back.  Don't do anything else until you have heard from Lehmann, so as not to give A2A the slightest reason to say you've voided the warranty.

 

It did occur to me to suggest that you might want to try the unit in someone else's system to see if you could replicate the problem, but probably not a good idea until until you've heard from Lehmann.

[Guest thathifiguy]

Has a new local distributor been assigned? If so, they take ownership of warranty related issues.

[Decky]

Every exotic fuse story has a sad ending. 

[rocky500]

Has it blown a Jaycar Fuse?

 

I tried for a time some SR fuses and they blew after a few times in my amp. Always on power up. Their reply was to go from the 4A fuse to 5A one.

Even though I tried a littelfuse 3.15A fuse many times and it did not blow. (what I had handy at the time)

 

I just don't think they are exact on these exotic fuses and it can be a hit or miss when you power up your device.

Edited January 20, 2020 by rocky500

[aussievintage]

2 minutes ago, rocky500 said:

I just don't think they are exact on these exotic fuses

Or on most fuse sizing in power.   

[kelossus]

It hasn't blown a Jaycar fuse yet. I haven't really had a Jaycar fuse installed for an extended period of time like the AHP/AMR ones. It may be too early to tell.

 

The first fuse was either DOA or blew as soon as I plugged it in for the first time. The 2nd fuse blew yesterday when unplugging/plugging in the unit.

 

I haven't followed anything up yet. I replaced the fuse this afternoon and the unit powered on but I haven't listened to it yet.

[LogicprObe]

 

Well, I would turn it on and off a few times to give that fuse a workout.

Sounds like an inrush problem but SloBlo is supposed to overcome that.

[Telecine]

1 hour ago, kelossus said:

It hasn't blown a Jaycar fuse yet. I haven't really had a Jaycar fuse installed for an extended period of time like the AHP/AMR ones. It may be too early to tell.

 

The first fuse was either DOA or blew as soon as I plugged it in for the first time. The 2nd fuse blew yesterday when unplugging/plugging in the unit.

 

I haven't followed anything up yet. I replaced the fuse this afternoon and the unit powered on but I haven't listened to it yet.

Just an observation, it appears to blow these “audiophile” fuses when you are changing the cabling. I would be looking at the IEC socket and power lead.

Edited January 20, 2020 by Telecine

[kelossus]

1 hour ago, LogicprObe said:

 

Well, I would turn it on and off a few times to give that fuse a workout.

Sounds like an inrush problem but SloBlo is supposed to overcome that.

Yep I was thinking the same thing. Will give it a go.

34 minutes ago, Telecine said:

Just an observation, it appears to blow these “audiophile” fuses when you are changing the cabling. I would be looking at the IEC socket and power lead.

Will look into the cabling too. I am fairly sure I have run a few different cables with the unit but I will have another squiz. Thanks.