MOSFET! Could It Be A.... Sanyo?

[gonzothegreat]

Back in October I found the Plus 55 amp and I was impressed by the solid build quality. I need to dig out my plus 55 tuner (which has its fans over at the tuner info center) and try them out with a Hitachi preamp I have sitting around.

 

[FantasySage]

Yay mosfet! Gotta say i am in love with my sherwood. I kinda bought it out of the blue without knowing much about it, but damn am i glad i did. Now i just need to get the matching pre-amp (there is a tuner up on ebay)

 

[T-800]

I am using an AM-7040. I like it, it's a very nice amp and has lots of power. I could take some inside pictures of mine if people still want to see the inside of one.

 

[sejose]

I too have the Sanyo Plus Series P55 C55 and T55. I recently recapped the amp and now the right channel has a scratchy-staticy noise proportionate with volume. No signal, there is absolutely no noise even with the volume all the way up. I'm kind of at a loss as to where to look for the source of this noise.

Any experience here would be helpful, thanks!

Scott

 

[gonzothegreat]

I have my Plus 55 amp on the bench and I'm surprised the thing worked the last time I used it. Every damn electrolytic was shot (including the 4 big ELNA caps). To check the ELNAs you need to feel the plastic tops. If you can feel a little triangle through the plastic, they're toast. Plenty of heat damaged solder joints on the driver boards as well.

Scott - The staticy noise is almost certainly a transistor issue - probably either the input diff pair or the next stage. Double check all the solder joints. FYI www.manuals-in-pdf.com has a PDF service manual for $15.

 

[javelin79]

That amp is very very clean THD wise. .0009. I have 4 of them and use them strapped. The C55 Plus series preamp that matches it is one of the best preamps ever. Compares to a carver C2 easily. The are only 8ohm amps. They will not take a 4 ohm load. If one pops up on that auction site they sell for alot of money. In 1983 my grandfather bought one of those amps. They were only for sale in the US for a short time. They were then taken off the shelf. Anyway he took the amp he bought for like 329 dollars to a AMP clinic put on by hitchcock labs. Anyway they spec'd the amp and they like to have fell over backwards. It was better then any of the high end amps in the stereo store that were there at that time. Hope that helps and enjoy the amp as it is rare and very very clean.

 

[tubeboob]

I also have the AM-7040 and matching Preamp AP-7020, both purchased NOS about a year ago. They sound amazing. This Amp has punch, definition, dimension, clarity . . . it's really an aural beaut/brute. The AP-7020 also is amazing, as I have tried it as a preamp with my tube amp and its clarity and delivery is very high end. These are definitely sleepers.

Additional mosfets that I have include the Sanyo P55 in silver purchased from Germany where they were available in silver, and I have the matching silver preamp. While the preamp is switchable between 220v and 110v, the amp is not. But looking at the inside of the amp, it appears that to use 110v is only a matter of switching some wires.

The amp is in need of some repair, and I just got a set of 8 2sk134 and 2sj49 NOS Hitachi mosfets. I've been looking for about 1 1/2 years to get a set at a reasonable price. Usually a pair goes for $25.00 to $30.00 plus around $5.00 to $10.00 for shipping. I got my set for $60.00 delivered.

The amp is currently in Tampa at my technician, like I said, we've been awaiting the mosfets for quite a while now, and I am looking forward to fixing it up.

As soon as I get it fixed, I shall provide an update. I always look for these mosfet amps, as they sound great, with tube amps being the only beasts that will be chosen before the mosfets.

I am looking for the Tuner and the tape processor in Silver so that I can have a matching set, but I think that will be difficult to find in the USA. I can always have a "black and silver" set??

Cheers

Donald

 

[highfigh]

Next time you're sitting around talking trash with your MOSFETid friends, stump 'em with this one: "What '80s amp uses the classic Hitachi 2SJ49 and 2SK134 in TO-3 cases, two complementary pairs per channel, just like the Hitachi 8500 Mk II; dual transformers just like the Hitachi 8500 Mk II; bridgeable just like the Hitachi 8500 Mk II; 100 watts per channel just like the Hitachi 8500 Mk II; headphone jack just like the Hitachi 8500 Mk II-- but ISN'T an Hitachi 8500 Mk II? and doesn't at all resemble the otherwise similar Sherwood S-6040CP? ..Ha ha! Give up?"

SANYO P55 MOSFET AMP

It's the circuitbreaker-equipped, LED-metered, surprisingly well-built Sanyo (yes, Sanyo, the folks who make those very reliable nickel-metal-hydride rechargeable batteries) Plus Series P55 MOSFET amp. About the same shape as the LED-metered Sherwood (which is also a twin-transformer design), inside they look nothing alike (nudesters to follow). In fact, the Sanyo is cooled with a heat pipe, a la Kyocera. You can hear the heat pipe gurgle when the amp's been running awhile.

Like the Sherwood, the Sanyo was on the market for a disappointingly short time and came with a matching tuner (T55) and preamp (C55). Unlike the Korean-built Sherwood, the Sanyo was a product of the home country, Japan.

The sound? Glorious. Driving a Stax Lambda Pro with the Sanyo gives the lie to the old wives' tale that electrostatic headphones don't have percussive bass. The Ultrasone demo CD never sounded so good. On the other hand, it's not much different, so far, from being a smaller Hitachi HMA8500 Mk II with LED meters and less of a brutal look. More details and impressions later. Oh, the photo shows the P55 driving a pair of damped Yamaha Orthodynamic headphones, model YH-1, with a lot of bass boost from a Yamaha C85 preamp.

The speaker selector knob shown is not original.

Sanyo had a VFet amp, too. They're one of the largest semiconductor manufacturers in the world.

 

[cutra]

Great amps

Hi Everyone,

just stumbled across this thread and found it very interesting as I own the complete Plus Series system. And to this day the Plus P55 has incredible specs and great sound. I bought the complete system in November 1982 and paid around $2800CAD for it at that time. I have all the original manuals, boxes, etc. as well if anyone needs to know any of the specs etc.

The complete system is as follows:

Plus P55 Power Amplifier
Plus D64 Cassette Deck
Plus T55 Tuner
Plus N55 Noise Reduction Adaptor
Plus C55 Preamplifier

I have been using it since 1982 with various loud speakers from Infinity, Acoustic Energy, Pioneer, etc. and I am still a huge fan of this amplifier. I only use the Amp and the Preamp right now. The other three components are in their boxes in the basement storage room.

Just to give you an idea of the specifications for the P55:

Continuous power (at 8 ohms) (Normal) 100 watts x 2 (0.009% distortion)!!
(Strapped) 200 watts (0.03% distortion)

Intermodulation distortion (60Hz:7kHz - 4:1) (Normal) 0.009% (100W output, 8 ohms)
(Strapped Mono) 0.03% (200W output, 8 ohms)

Transient response: Slew rate (Normal) 150V/usec

Damping factor: (Normal) 60 (at 1kHz, 8 ohms)
(Strapped Mono) 0.7V/47 kohms

Frequency Response: (Normal) DC-100kHz (+0dB, -1dB) (1W output, 8 ohms)!!
(Strapped Mono) DC-100kHz (+0dB,-2dB)

Signal to noise ratio: (Normal) 110dB!!

You can put these specs up against a lot of the new amplifiers in the high fidelity arena and it will stand up quite nicely.

If you can pick up a working one on eBay for the ridiculously low prices I have seen claimed go for it.

Cheers.

Tony

They are fantastic amps!
I have 3 working ones and 2 non working ones.
Once I get my life back on track I'm going to get them all looked at to make sure they
are all good....

 

[Andy_H]

…
Caveat #1: Turns out that many of the C55s up for auction either have nonfunctioning power switches or none at all. My seller actually replaced the switch on this one. Odd thing to have as a bad part, but there you are. Not a dealbreaker, but it makes you wonder.

Date sticker on the bottom of mine says 091179, which probably indicates an early one.

…

Reviving this thread with questions/comments on the power switch. I bought a C55 a few months ago and have been happy with it but it has developed a problem that appears to reside in the power switch - the switch certainly seems to be a trouble spot in these. With mine, when I powered it on, it started to make a crackling, sizzling sound from the pre and an awful buzz came through the speakers. Turning down the volume and changing the input did not stop the buzz so I quickly shut it off and went looking for the source of the noise.

I put it on my workbench, removed the top, and powered it on, listening carefully to pinpoint the exact source of the crackling. It seemed to be coming from the power switch, so I removed the switch and temporarily wired in a generic SPST, turned it on and no more crackling. The original switch is an Alps, labeled "Snap Switch N 53". At least I think it reads "N 53", but the print is tiny. On the top it reads "TV-5 SDU1P 940". Google didn't turn up any matches for those numbers but I did find some relatively similar looking Alps switches labeled "TV-5". I'm not sure what would be right to replace this. Does anyone know what the best replacement for this might be? Pictures:

Date code on mine reads "101279" so October 12, 1979, I suppose.

 

[audio3000]

Mine had the same problem many months ago when I first bought it. It's a common problem on P55. I could not find a direct replacement for the power switch. So I just squeezed some dry contact cleaner thru those tiny holes on top and the problem has gone and could not hear any sizzling sound when I put my ear close to the power switch couple minutes ago.

Last week, I found two dry up 10uF caps on the current source base. Only these two were dried as my cap ESR meter showed. But I also replaced the other lower value caps. Luckily the big caps are still very good. It took couple of days to clean up the sound after the cap replacement. Then the amp runs even cleaner.

Good luck...

A3K

 

[HOOG]

Andy_H - did you ever find a replacement? I have a Sanyo 2033 receiver that is exhibiting the same power switch problems. Same switch from your photo, but a slightly different mount and external resistor/capacitor. I would like to replace it with the same part, if possible. Thanks!

 

[Andy_H]

Andy_H - did you ever find a replacement? I have a Sanyo 2033 receiver that is exhibiting the same power switch problems. Same switch from your photo, but a slightly different mount and external resistor/capacitor. I would like to replace it with the same part, if possible. Thanks!

Man, I had forgotten about this thread. I didn't end up finding an exact replacement. What I did was take the old switch into a local electronics shop where they have a huge bin of miscellaneous switches, dug through until I found a similar-looking one and replaced the original with that. I don't use this pre very much lately but it works fine with the replacement switch.

 

[rnorton]

Sanyo Plus series gear was all very good (and usually not actually made by Sanyo).

 

[HOOG]

Man, I had forgotten about this thread. I didn't end up finding an exact replacement. What I did was take the old switch into a local electronics shop where they have a huge bin of miscellaneous switches, dug through until I found a similar-looking one and replaced the original with that. I don't use this pre very much lately but it works fine with the replacement switch.

Thanks - I'll keep searching!

 

[TimF]

Boy, talking about bringing back some memories looking at these pics of the Sanyo "P" series. I bought the amp, preamp, tuner and also the matching cassette deck new in 1981. The amp was very good I thought at the time, the pre and tuner were okay. The tape deck gave me a bit of problems in the transport section from day one, but once sorted, good to go.

Mine all had the rack-mount ears and it all looked very good sitting in a Sansui rack-mount upright stand. The gear was powering some 3-D Acoustics towers at the time. Loved hearing the gurgling from the cooling system in the amp once you turned everything off for the night.

One thing I also loved about this gear is that all the controls-volume/tuning knobs and switches just felt nice to operate. Decent stuff there, should have kept them, but then again, should have kept most of the gear I have had! Thanks for the pics guys, great fun! Tim

 

[wualta]

Belated thanks to Andy H for giving us a closeup look at the C55's power switch problem. If I haven't mentioned it earlier in this thread, I've since read of a few owners of the P55 with power-switch problems.

This reminds me of the trouble Radio Shack was having with switchgear in its late-'80s electronics made by its own TCE (Tandy Corporation Electronics) factory in Korea.
.

 

[Cesari0]

I know this thread is old.
I'm posting this just in case someone runs into the same common problems the Alps TV-5 SDU1P seem to suffer from.
I had a Sanyo Plus A35 sitting around. Finally decided to work on it.
After it was all said and done, some noise was coming from what I thought was the transformer... after close inspection it was the power switch causing the noise.
I tried to fix it, I accidentally broke a piece of plastic... which meant I had to think of something else, it was not fixable.
On a side note, the inside mechanism in the switch is flimsy.

So this was my fix, you can use any microswitch... I chose this one because it was the closest to me.

 

[leesonic]

Mouser part # 611-NE1839EE might work.