Sanyo PLUS 55 receiver

[Tripqzon]

I recently decided to check out a receiver I had given up for dead many years ago. I has been in storage for a good 14 or 15 years. I put it away in hopes that some day I would tear into it and bring it back up to snuff. By the way, I bought it new around 1980, traded a Technics receiver at Deorsey's audio store for it.

Let me start by telling you why I put it out of service.

1) The Power Switch was failing. I could hear sizzling noises coming from it.

2) Some of the switches and knobs were causing intermittent audio drop-outs.

3) The Quartz-Locked circuitry had failed and fried a TO-220 regulator transistor on the power amp board. There was no output at this point. The output relay would not activate. The transistor got so hot that the foil traces on the board around the transistor were destroyed.

4) I became very discouraged at this point and stooped to purchasing a Pioneer HT receiver (VSX-501). Don't get me wrong, I love Pioneer (I own a few vintage pieces as you can see from my signature) but thought going HT was the cool thing to do at that point.

Anyway, I got it back up and running except for the Quartz-Locked circuitry issue. The quart lock does not work at all and it appears that whatever went bad must have created an open circuit because the new transistor is holding up fine.

I hadn't heard it for so long and was surprised. It actually sounds pretty good. It has a good strong low end for a 55w/ch receiver. Good open soundstage. Plus it has a nice apparence.

I am wondering if anyone here owns or has owned one of these receivers and what you think or thought about its sound and build quality.

I've attached a photo. I apologize for the quality of the photo. The lighting was not good when I took it.

Thanks,
Paul

 

[GuyNoir]

Sure is an attractive girl!

 

[omer]

The Plus series stuff was WAY ahead of it's time - hell it's even better than some current stuff! :drool:

 

[prin1983]

My dad purchased a Sanyo Plus 55 back in 1979. My dad decided to gave it to me. It's in the shop now getting new transistors, new pilot lights, and other things done to it. Mine has the same problems too. The ICs gave way a few months ago after almost 27 years. The Plus 55 was Sanyo's basic Plus Series receiver in 1979 and the line went up to the Plus 200, yes Plus 200. If you remember, the Sanyo Plus Series included Intergrated Amplifiers, Tuners, Turntables, noise reduction units, and cassette decks. I'm very sure that Plus Series line included more items. Sanyo's Plus Series line was developed as Sanyo's high end to compete with brands such as Pioneer, Technics, Sony, and others in the mid range product chain.

 

[sanyofreak]

I have a Sanyo Plus55 and have found it to be a very fine performing receiver. The power switch issue is a common one, and may not be Sanyo's fault, as the switch is sourced from ALPS - but let me state again, it is a very weak point on not only the Plus55, but the higher units in the series as well. (receivers) What surprised me the most about this unit is its "wallop per size" factor, as it really has a small footprint, but very solid output that seems much bigger than its size suggests. When You pick it up, its weight is a surprise. The quartz lock issue maybe a simple one as well, but a service manual is pretty much necessary to find it, service manuals for this short lived run of Sanyo gear are not easy to find. The bulbs and the regulator transistor are no different than many other Vintage units, par for the course in a 26 year old unit.
Its a good clean, clear sounding unit with low end authority that is amazing for its power rating.
I think that as time moves forward, certainly the Sanyo Plus series, along with some other Vintage heavies they produced, will gain respect as units worthy of owning and enjoying, and I hope You like Your Plus as much as I do. Congrats on bringing her back among the living.

 

[dr*audio]

The quartz lock has nothing to do with the output stage! It is for the tuner section, used to keep the stations locked in. It sounds like you had blown outputs in the power amp. I doubt the TO-220 transistor was a regulator, most like ly it was a driver transistor. What is the problem with it now, do you get sound but thestations won't lock in, or no stereo reception?

 

[sanyofreak]

Doc,
If I understood correctly, and from experience with these models, our original posters unit indeed had all (4) seperate problems, being, power switch, burnt regulator,scratchy controls, no quartz lock, - and then someone else's unit had blown IC's. The original posters fried regulator transistor traces may have left the relay control circuit dead. The unit with the fried IC's, also may have had no relay engagement. The quartz lock remains the unsolved issue on the first unit, the second unit did not say if the quartz lock was also an issue with his.
With this unit, the quartz lock can be switched off manually, and may render the tuner otherwise functional. It can still receive in stereo. If this is the case, it may help someone like the doc with some troubleshooting tips. Maybe I'm reading the history wrong here, sorry if so, tryin to help.

 

[Tripqzon]

Doc,
If I understood correctly, and from experience with these models, our original posters unit indeed had all (4) seperate problems, being, power switch, burnt regulator,scratchy controls, no quartz lock, - and then someone else's unit had blown IC's. The original posters fried regulator transistor traces may have left the relay control circuit dead. The unit with the fried IC's, also may have had no relay engagement. The quartz lock remains the unsolved issue on the first unit, the second unit did not say if the quartz lock was also an issue with his.
With this unit, the quartz lock can be switched off manually, and may render the tuner otherwise functional. It can still receive in stereo. If this is the case, it may help someone like the doc with some troubleshooting tips. Maybe I'm reading the history wrong here, sorry if so, tryin to help.

My unit has the Quartz-Locked tuning issue left to resolve. It still receives FM stations just fine. The only problem with that is after it has been on for a short time I have to retune the station just a bit as it will drift just enough to loose the station. But after I retune it will stay on the station all day long without any drifting at all. I assume this is the effect of components coming up to temperature.

Paul

 

[dr*audio]

You will need a manual and an oscilloscope to track this down. The quartz lock is a PLL (phase locked loop) circuit, that tracks the drift in the local oscillator in the tuner. The circit puts out a control voltage to a varactor diode in the LO circuit. The varactor is a special diode that acts like a variable capacitor, whose capacitance changes with the voltage across the diode. The circuit will have a reference oscillator (the crystal) and then it requires a signal of some type from the tuner to tell if it is properly locked. Sometimes it's just a DC voltage from the discriminator, and if it varies from 0V, the PLL knows it's detuned and applies a correcting voltage to the varactor to retune it. In this case, because it has a reference crystal, I think it may have some kind of digital detector that puts out pulses that get compared to the reference oscillator. Anyway the manual is necessary for you to check the presence of the various signals to find out where the problem is. Often the varactor goes bad, but sometimes it's the PLL chip. You can try just replacing the chip if you can figure out which one it is. You can write down the part numbers on the chips in the tuner section and google each one until you find the one that is the PLL.

 

[Windwalker]

I have one of these that the power switch went out on
How hard a replacement is it?