Nakamichi PA5-II Power Amp Fuse Question

[MrMacphisto]

Greetings all.

I have recently acquired a beautiful example of a Nakamichi PA5-II Power Amp along with the Nakamichi CA5E-II Pre Amp (only one previous owner!). I had set it up over the weekend and was enjoying its rich sound for about 30 minutes before I needed to turn it off. Upon turning it back on again, I saw I had no power to the power amp. Upon closer inspection, I discovered the in-line fuse had blown. Upon removing the fuse I can see that its a T4A/250V type glass fuse, however I strongly suspect its not the original fuse.

My question to the group is if anyone knows what the correct fuse to use for the Nakamichi PA5-II Power Amp (UK Voltage)? Is it a T4A/250V? I have referred to the original manual and unfortunately it says rather cryptically (as it was designed to cover all regions) that should the fuse need replacing to either replace with the spare fuse originally supplied (which I don't have) or contact the local authorised service centre. I have looked across the forums and also at the service manual and have a read a host of different things. Does anyone own one/have a definitive answer?

I have ordered a pack of 10 T4A/250V spare fuses for approx £3, however as I'm sure you'll all agree it would be a pain having to replace them frequently. The amp was fully serviced last year.

Looking forward to your wisdom!

[Firebottle]

Hi Khushru, it wouldn't surprise me if the T4A is the correct fuse, particularly if the amplifier has a large toroidal transformer in it.

Bon chance.

[DSJR]

It's a high powered amp. Once imported by B&W, I'd give them a call for further advice as to current servicing details if needed.

I said elsewhere here this morning, use the preamp as an ornament (it's veiled in sonics from memory, as was the CA7, but may make a fair phono stage if used from the tape outputs), replace with a passive one to taste (I make NVA's here, so I'm biased, but sale or return on a P50 should quickly prove my point) and ffs, leave the bloody mains conditioner out of it, as many 'domestic grade' ones not costing thousands will slug the current available for such a big amp demand. Big amps like this need only be connected to a suitable wall socket and the large transformer should absorb most nasties coming in. Some clip-on cable ferrites could be used if you want to play perhaps..

Sorry, I'm not telling you what you want to hear, but not many here have owned or used these amps (I sold them as well as we were one of the few UK dealers for big Nak amps, which were very good but totally lacked cachet of the then inferior Linn and Naim offerings, even into 3-4 ohm loads!!!) and I think my recommendations could be borne out by your own listening.

[struth]

In uk if memory serves it was a 2.5amp fuse. There was a full schematic online somewhere. Will see if i can find it

[struth]

Found this

May be the standard model not mk2...it didnt say.

[MrMacphisto]

It's a high powered amp. Once imported by B&W, I'd give them a call for further advice as to current servicing details if needed.

I said elsewhere here this morning, use the preamp as an ornament (it's veiled in sonics from memory, as was the CA7, but may make a fair phono stage if used from the tape outputs), replace with a passive one to taste (I make NVA's here, so I'm biased, but sale or return on a P50 should quickly prove my point) and ffs, leave the bloody mains conditioner out of it, as many 'domestic grade' ones not costing thousands will slug the current available for such a big amp demand. Big amps like this need only be connected to a suitable wall socket and the large transformer should absorb most nasties coming in. Some clip-on cable ferrites could be used if you want to play perhaps..

Sorry, I'm not telling you what you want to hear, but not many here have owned or used these amps (I sold them as well as we were one of the few UK dealers for big Nak amps, which were very good but totally lacked cachet of the then inferior Linn and Naim offerings, even into 3-4 ohm loads!!!) and I think my recommendations could be borne out by your own listening.

Dave, thanks for the advice. I saw your other post as well. So what your saying is that I will get better sound quality if I were to use the tape (recording) outputs instead of the line outputs? I am currently the CA5 using as phono stage for my MM cartridge. I may well look into purchasing a dedicated phono stage in the not too distant future, but I suspect I would probably get a better return from my money by investing a decent MC cartridge before upgrading to a dedicated phono stage (as the CA5 certainly isn't bad IMO). Is this the right approach?

[MrMacphisto]

In uk if memory serves it was a 2.5amp fuse. There was a full schematic online somewhere. Will see if i can find it

Grant, thanks. I have a copy of the Nakamichi PA5 Service Manual, however for anyone else who may need it, it can be found at the following link:
http://www.creapromedia.fr/lesdocs/nakamichi/pa5.PDF

The manual is for the Mk1. The image attached is taken from page 1 of the service manual, and you can see it recommends a 6A fuse for US/Canada/Others (so will assume UK falls into that bracket) and a T2.5A for Australia & Canada.

Untitled.jpg

[struth]

Us/canada will be about twice ours due to their supply being half. The mk2 may be a bit more than mki but i wouldnt think it would be much more. 2.5 amp anti surge or 3 amp sounds right, but if its done no harm with what in..... Is it a quick blow type in?

[MrMacphisto]

Us/canada will be about twice ours due to their supply being half. The mk2 may be a bit more than mki but i wouldnt think it would be much more. 2.5 amp anti surge or 3 amp sounds right, but if its done no harm with what in..... Is it a quick blow type in?

I believe a T4A is a slow blow. Like I said originally, I have ordered more of the T4A but just wanted to see if anyone knew definitively what the original fuses were.

[DSJR]

I can't remember the fuses as I never had to replace any of them. The PA5mk2 was different sonically to the original and was more like the PA7 in miniature I remember.

I'm suggesting using the CA5 II as a phono stage only and taking the fixed level tape out to a passive preamp for volume duties*. If the interconnects are low capacitance and less then 2m or so, I'd suggest a clearer sound could be achieved and with real front to back air and space...



* It's my view and from experience that many 'active' preamps in the 70's and 80's actually got in the way of the signal and altered the sound quite noticeably from input to output. The thing is, many US based audiophiles got used to the more rounded tones of their beloved valve gear that hearing a preamp that did nothing (as much as possible) to the signal passing through it caused great distress and accusations of harshness, which actually wasn't there. In the late 80's it was common to use a warm and soft toned (but still clear sounding) ARC valve preamp to match the increasingly harsh sounding and baking-hot running 'bigger' Krell power amps of this period, which were as nasty in real terms as many basic PA amps, just far hotter and far more expensive. I thought Krell came back with the plateau-bias models and I remember falling in love with their first FPB models, which really were amazingly good, but I digress. Obviously my opinion based on experiences at the time, and I'm trying not to exaggerate... I had an ARC SP14 for a couple of years until I heard a Croft at a third of the price at least equal it. The SP14 wasn't as revered at the time, as it sounded more 'accurate' and less 'cuddly' than previous models I recall..