Pioneer SX-1280 Part 6 - Circuit Theory & Assembling the New PC Boards

[@g.fortin3228]

Awesome Tony. this one's really coming together quicker than expected... Looking great.

[@greengrayradio1394]

Nice job as always, Tony!

[@AUTISTICLYCAN]

Another funny fact. I brought my Pioneer SX-1250 and Pioneer SX-1980 power and other board upgrades from the same dude in Canada you reference. Only difference I got the version he sells that has all the electronic bits set in place. My repair people use the same chap. He also supplied all my boards for my Pioneer SX-1250. Nice to know I choose my upgrades well. The best thing is all the awesome upgrades in these boards still lets this huge Pioneer SX-1280 receiver sound just as awesome. I like the black meters and colored function lights unique to the Pioneer SX-XX80 Series.

[@jeremiahchamberlin4499]

Thanks for the analysis of the original vs. the modified circuit, Tony. I always learn something from your reviews.

[@bobdoritique7347]

Merci for this video. What is the model or reference of the metal plate with the magnetic tips to hold the PCB please?

[@philipslighting8240]

I have ben looking forward to this video. Thanks Tony. Mike.

[@keeper1855]

Thanks Tony!

[@RCampbell-y4b]

Really enjoy your channel. Thanks

[@t1d100]

When I flip a component and get aggravated with myself, I just remind myself that, if that is the worst thing that happens in my day, its going to be a really great day. Cheers.

[@SkyhawkSteve]

I do find those discrete voltage regulator designs interesting! Modern regulators, such as the venerable LM317, offer a lot of advantages in terms of reliability and ruggedness. However, they aren't designed for the high voltages seen in some hardware, so the discrete design still has some utility. One of the easy things to do to improve the reliability of a regulator is to keep the temperatures low... well below 85C... so a big beefy heatsink is a great idea.

[@seanobrien7169]

Haha loved the foghorn leghorn reference.

[@erikdenhouter]

Hi Tony. I hear you often say that the gain of transistors have gone down over the years by heat. But please see that the manufacturers use low gain transistors in places like regulators, because they are cheaper, and the schematic doesn't matter at all for high gain, it will work anyway. The only thing it does is open or close more or less.

[@thomasswift2195]

Tony, When looking at an LED, what you call the anvil is shaped like an arrowhead and it is pointing toward the positive lead. So just remember the arrowhead/anvil (USUALLY) points toward positive.

[@xraytonyb]

Another good tip. Thanks!

[@acoustic61]

I wasn't aware of replacement boards. I wonder if there are any for Marantz?

[@xraytonyb]

No. Delta9electronics is the name of the company and they only have replacement boards for certain Pioneer gear, as well as some Hafler gear.

[@acoustic61]

@@xraytonyb They got some cool stuff. Have you tried their STK-0050 replacement Modules?

[@Parkhill57]

I enjoy watching you build the boards, as I used to love kits as well. But about age 60 or so I find I don't have the patience anymore. I have two kits waiting to be built, and I just can't get motivated. I think it's burnout, but may be just old age. In any case, there would be at least 6 empty beer cans on my bench.

[@MIJ_Pioneer]

Great video I really enjoyed the detailed analysis of the old/new circuits. I am running the same Delta9's AWR-157 power board in my 1280 and its been worth every penny. I have my 1280 ready for the bench to compliment some of your suggestions through this series. Particularly fixing the rather crude connections to the main filter caps (using a jumper wire vs using the original bracket for ground). Do you have any thoughts of adding additional 2.2uf PP caps across the filters? Also last video you mentioned making a replacement awx-127 to accept modern outputs. Did you have a chance to review the ones I recently used on my 1280 (post #10 & #38 on thread " SX1280 - Power Amp burned up a resistor" AudioKarma).

[@jansen2810]

I realise the new boards are better than the original ones, who still lasted over 40 years, but what about originality? Where do you stop with enhancing? I’ll bet someone at one time comes up with better output stages or a better preamp design. What will be left of the vintage character of this beauty? Why not use the original boards and restore them for another 40 years with new components. Not that I don’t love watching the process and learn from it, but it just made me think.

[@xraytonyb]

I place a high value on originality if the goal is to keep it as a piece of history and not actually use it. Pioneer receivers of this era were known to have problems with the power supplies. Quite often, the heatsinks were undersized and the resistors rant hot and were positioned near the capacitors, causing them to fail. Most of these units didn't last 40 years without having to have the power supply rebuilt. The new design corrects these issues without affecting the audio performance of the amplifier. In 30 years, this unit will still sound as it did new, with possibly only needing some capacitors to be replaced, and not scorched PC boards! In addition, the original board can be kept with the unit and reinstalled for originality.

[@jansen2810]

@@xraytonyb I have no intentions to contradict my teacher, I have learnt so much from you. Besides the topic is very interesting. To me however it's putting a Porsche engine into an old VW Beetle.

[@geoffreykeane4072]

Good question and good answer.

[@seanobrien7169]

@@jansen2810 That is a great analogy (me being an air cooled nut from way back). If you are going to drive the car even on a semi-regular basis though you will have made some mods. Especially as you go back to the older pre-67 cars you will have swapped to dual port heads, 12 volt electrical, maybe even front discs. Hopefully you kept the original parts (if the car even had them...most have been lost a LONG time ago). I remember back in the 80s matching numbers was of the utmost importance for muscle cars. While that gets you premium price today it is amazing how it has lost its importance among us common folks. Today we are just happy to find anything that is drivable.

[@jansen2810]

@@seanobrien7169 The analogy was a bit over the top. Could not think of anything better. It came up probably because my first car was a 1968 VW Beetle. 12 volt electrical, no front discs yet. A Porsche engine would not have fitted. :-)

[@discountwire9120]

Been watching your channel for a while now. I dont have the skill, patience or knowledge you have so my 1280 sits needing repair. The vintage audio guru in my area passed away and now Im stuck with no local help. Can you recommend somewhere I can send my baby to? Its not the type of unit I trust any old place with. Its was my Father’s so sentimental value is immeasurable.

[@erikdenhouter]

Trevor's bench on youtube maybe ? Waiting list for sure...

[@RGD-Audio-Repairs]

that tool to bend the component legs at exact width.. What is that called, Please? Might see if i can download one to 3D print... They look brilliant!

[@markk.4941]

Called a lead bender. About $4.00 on amazon

[@garp32]

It's the simple things in life. That's a pretty slick looking gadget and offers consistency. I can never seem to bend 2 the same and the OCD in me drives me nuts! Gotta get me one. Great video as always, Tony.

[@afnDavid]

I say! I say! I say!

[@harryhirsch9135]

yep, I can't stand that tilted transistors as well.

[@andymouse]

Its good luck to have a bird crap on your head like stepping in dog poo is good luck too, so I'm told (in the UK) I think it has to do with Karma....cheers.

[@xraytonyb]

Luck was not what i was feeling at the time 😕

[@andymouse]

Yeah, I don't get it either !!!!@@xraytonyb

[@401ksolar]

This "war on cpu resources" that yt is perpetrating under the guise of adblock war is causing coolateral damage to those of us who do not use adblock, (ads play fine, comments work, but have to sign out to see video) thumbs down on excessive resource hogging.

[@jdmccorful]

Live and learn! Thanks for the show and tell.