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Pioneer SX-780

AM/FM Stereo Receiver

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Pioneer SX-780

Description

The SX-780 features a high output, low distortion power amplifier, a high fidelity equaliser amplifier with low noise and high gain, a high stability tuner section, tone controls with tone defeat function, built in protection circuits and independent power meters.

Specifications

Tuning range: FM, MW

Power output: 45 watts per channel into 8Ω (stereo)

Frequency response: 5Hz to 80kHz

Total harmonic distortion: 0.05%

Damping factor: 30

Input sensitivity: 2.5mV (MM), 150mV (line)

Signal to noise ratio: 76dB (MM), 95dB (line)

Output: 150mV (line)

Speaker load impedance: 4Ω (minimum)

Semiconductors: 5 x FWT, 11 x IC, 26 x transistors, 22 x diodes

Dimensions: 480 x 140 x 320mm

Weight: 11.2kg

Accessories: FM T-type antenna

Downloads

instruction/owners manual  English

service manual  English

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Reviews

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rating
Submitted by jarogerson

I have nothing bad to say about this receiver! It is my first dive into the vintage hi-fi world and has been absolutely fantastic. I got this from craigslist off of someone who found it at an estate sale. $60 for the beast and they threw in some run of the mill Sherwood speakers. I got it home and plugged it in...no cleaning or repair, just plug and play! I upgraded to new Sony 4 way towers and the sound is impressive, crisp from a very low volume setting through house rocking volume (which can be accomlished at the 10o'clock setting!). Running my TV/DVD/CDplayer/Sansui turntable through it, with fabulous results. Who needs surround sound when you have Pioneer SX780 Stereo!

rating
Submitted by IOC386

Pros: Great warm sound, decent power, cool look (UV meters, dude!)

Cons: Power relay tends to go bad, phono stage is a little noisy (but still better than most of the era), pots tend to get scratchy with age

This is a great tuner. It seems to be underrated for the power it puts out (I have no trouble cleanly driving a pair of cerwin vega LS-12's). Sound is decently warm, but can be a bit muddy at times. Overall has a pretty nice sound on a variety of speaker combinations. The preamp stage is better than many other (standard) 70's tuners, but it still has a bit of electrical noise as integrated phono stages tend to have. The tuner portion seems to be a little sensitive, and doesn't really lock in as well as some of the old onkyo's did.

 

Comments

snhalder's picture

re: SX-780

I love this retro receiver. A gift from my brothers (who thought the old guy would appreciate a receiver that was popular in his youth... ) ;-)
Just replaced the Onkyo TX-8511 in my office with this and really like the sound! Maybe it is just a better match for my ancient Speakerlab S3 speakers, but it is warm and sounds better for all types of music at all volume levels. Though the power output rating is technically lower, it seems to have much more top end - really stunning.

dmeth's picture

Pulled from a shelf in the garage....

So my parents have had one of these receivers in their garage since i was born, along with a pair of bose 301 series III speakers. The receiver was just sitting uncovered in the garage for years. Both the receiver and speakers were exposed to hot (>90) and cold (<32) temperatures, as well as various dusts and aerosols. the first test after hooking everything up yielded impressive results, with next to zero perceptible noise or distortion across frequency and volume ranges. The receiver also powers my sony MDR-V6 headphones very nicely (first time using these headphones with something other than my laptop or a portable device). Overall I am very impressed with this receiver. I was wondering if there is any sort of maintenance i should do considering the conditions in which the unit was stored in for 10+ years without use.

re: Pulled from a shelf in the garage....

The most important thing right away is to blow out all of the dust using compressed air or dust off. I've actually had receivers not working at all because all of the dust causing minor shorting between the components. The unit will also run cooler with the dust removed.

If you know how to solder, it's also not a bad idea to check all of the solder joints for cracking using a magnifying glass. If any is noted, it can be reflow end by applying a small amount of solder paste and reheating. If you decide to resolver the joint make sure you use a solder with lead like 60/40 to match the original solder, and always clean your work using either circuit card cord cleaner or denatured alcohol and a stiff brush.

Pioneer SX 780 question...

I recently purchased a Pioneer SX 780. It had bad sound when tuned to FM stations and barely had any sound when using the record player with it. I replaced the darlington power packs and the FM stations come in with GREAT sound now, but I have no sound from any other imputs. When I switch it to FM, after a few seconds you hear a click and the sound comes on. Switch it to anything else, nothing. Switch it back to FM, and again, after a few seconds, you hear a click and music. Does anyone have any suggestions as to what can be the problem?

SX-780

Yes I work on them and most of the time, they need cleaning of the selector swhich really good and then it lock in..

Jim Salamoni

re: SX-780 - protection circuit?

Hi. I saw this note regarding a pioneer sx-780. Mine has worked great the last 2 years but now doesn't send power to the speakers. Can you help describe how to troubleshoot? I used to turn on the unit and in 3 seconds or so the protection circuit would turn on and music would play. Now I turn it on and no 2nd sound. I suspect this switch is bad or dirty. I am not an electrician but figure I should be able to figure it out with a little help. Thanks in advance if you have any ideas/diagrams/descriptions.

Dan
Bellingham, WA

Delay in power on and Random Click Off

@hdstonemeister The receiver does have this delay. If you look at the service manual provided on this site, it notes that there is a delay due to the mute switch. I can attest that my receiver has the same behavior with any of the inputs. You turn it on, no matter the position and you get the delay.

I now have an issue where it clicks off, whenever the hell it wants to, in all input positions, and comes back on whenever the hell it wants to.

I feel like the board gets overheated or is overly susceptible to humidity, as it often seems to happen when the humidity has kicked up. Unfortunately I can't help you with your overarching problem, but I hope this helps you in some way. I'm asking my Dad, an 40 yr+ Electrician and Electronics geek to weigh in on mine, so I'll let you know if he has any ideas for yours.

Are your other inputs on when you click the dial over? I've found generally have to be on for you to hear it click onto the selected position. There is always a few second delay.

Delay...

Yes, I know there is a "delay", but this takes several minutes sometimes, not the few seconds that the manual states. I found out that the problem may be corrorided contacts within the switches. What I have done is ordered parts to do a complete recap and when I take it apart for that, I will clean the switches completely. Thanks for the help.

WOOOW

NOW I CAN USE MY FATHER'S RECEIVER!!! PIONEER ROCKS!!

SX-780

I just acquired this from my brother who got it at a flea market. I have not even powered it up but he said it seems to work. WIth the manuals , i will have no trouble checking it fully out.

Thanks.

SX-780

The manuals you have archived are a fantastic asset to the community. Thank you.

Thank you!

Thanks to the poster. After some 35 years my SX780 quit working, and I hope to get it sorted ASAP with the manuals I just downloaded.

sx 780

looking for the schematics on sx 780

pioneer sx 780

anyone have a sx 780 schematic diagram??

KCTV

...

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I'm looking for Pioneer SX-880 and can't find. This is the most similar. Thanks for yours web, allways will be useful.

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