SPEC-2 Refurb Help Please

[EchoWars]

I assume that you verified pins 1 and 2 are the relay coil? I can't find a data sheet for those relays.

Those TO-220 transistors can use additional heatsinking, but you have to consider that the originals went 30+ years. I'm not crazy about those big wings on the new heatsinks, and the stock heatsinks are electrically hot, so unless you insulated them, these are too. If you're convinced that they aren't going to touch anything else, then rock on. But kinda looks like they might interfere with the electrical connections at the bottom of the board. Anyway, I simply prefer to use a nice, tough replacement that can deal with the heat, the On-Semi MJE15032 & 33.

All that trouble, and you didn't replace the electrolytic caps? And that crappy tantalum input cap? Junk those things. Replace the 22µf 35V feedback DC blocker with a 68µf 16V Panasonic FM cap.

 

[laatsch55]

I was 19 when I purchased my first Spec components, course that was in the middle of the 70's oilfield boom up here. Had more money than we knew what to do with. and still have the gear.

Deep sixing the tantalum wasnt brought up when I did mine, It's now on the to do list, along with better caps than I put in.

Lookin good Surgeon, kinda overkill on the heatsinks, but hey, whose project is this?

 

[markthefixer]

Get yourself some insulating shoulder washers for the 4-40 TO-220 transistor screws
532-7721-7PPS to-220 mounting shoulder washers, 4-40 $0.29 ea

and some mica insulators:
534-4672 to-220 mica insulators $0.12 each...........

or a full mounting kit:
532-4880SG @ $0.91 with sil-pad insulator, screw, washer, lock washer, insulating shoulder washer & nut.
532-4880 @ $0.77 with thermal film insulator, screw, washer, lock washer, insulating shoulder washer & nut.
532-4990M @ $0.77 with mica insulator, screw, washer, lock washer, insulating shoulder washer & nut.

and electrically insulate those heat sinks, it's cheap insurance and GOOD practice.
I've taken to doing that whenever I can.

oh, those are mouser.com parts numbers.

also:
863-MJE15033G pnp to-220 bce 250v 8a 50w 30mhz 70hfe $0.87
863-MJE15032G npn to-220 bce 250v 8a 50w 30mhz 70hfe $0.87

as well as the heatsinks you used: 532-507102B00 just for grins....

 

[Surgeon]

I assume that you verified pins 1 and 2 are the relay coil? I can't find a data sheet for those relays.

Yes, I metered them as 2K ohms (in both directions == no diode) & bench tested them with my variable power supply @ 24VDC (in both directions == no diode) -- I know they are hard to find so I took a chance and ordered a few & they worked out perfectly.

Those TO-220 transistors can use additional heatsinking, but you have to consider that the originals went 30+ years. I'm not crazy about those big wings on the new heatsinks, and the stock heatsinks are electrically hot, so unless you insulated them, these are too. If you're convinced that they aren't going to touch anything else, then rock on. But kinda looks like they might interfere with the electrical connections at the bottom of the board. Anyway, I simply prefer to use a nice, tough replacement that can deal with the heat, the On-Semi MJE15032 & 33.

I used the On-Semi 32/33's also, but figured the additional heat sinks could only improve their lifespans as well. And my amps, which I purchased new in '78, started showing their turn-on 'protection' issues within the first 5 years (maybe because I used them so much back in the days) and have gradually gotten worse. Like the old saying goes (the way I remember it): HOPE for things to go well but PLAN for them to ****-on-you any time they get the chance! :yes:

And it's hard to decern in the photos, but there really is lots of clearance around them and they sit above the circuit board itself by almost 1/2", easilly clearing smaller components. Plus, they are lightweight alumninum so they are quite easy to bend away from any taller components yet, because they are firmly mounted to the originals, they would never move on their own. I understand that they are electrically the same as the transistor's mounting tab, but honestly once they are 'formed' they should pose no more of a concern than the exposed legs of the transistors themselves...

All that trouble, and you didn't replace the electrolytic caps? And that crappy tantalum input cap? Junk those things. Replace the 22µf 35V feedback DC blocker with a 68µf 16V Panasonic FM cap.

And just exactly where was that sage advice when I asked for it at the begining of this thread when I was ordering parts?!? :scratch2: :scratch2: :scratch2:

Seriously though, is it safe to replace all the 35V electrolytics with 16V flavors or is there a list of which-to-replace-and-with-what? (And it's a good thing you brought up replacing them as upon closer inspection I found the bottom plug oozing out of the 10uf/50V next to the 22uf/35V DC blocker you mentioned.)

As near as I can tell on each amp board we have (from left-to-right):

10uf/35V electrolytic
47uf/35V tantalum
10uf/50V electrolytic
22uf/35V electrolytic

so what should I use for replacements for each of those?

And is there anything else I'm overlooking that needs attention? I really don't mind so much ordering lots of parts but I *hate* all those individual small-order shipping charges! (Hell, my wife thinks I must be having an affair with the UPS driver as it is...)

THANKS!
-Surgeon-

 

[laatsch55]

General rule of thumb is you can go up in voltage on caps but not down. Tantalum caps in the signal path are taboo, why the factory did ? Who knows?
Non signal path caps, Panasonic FM series, if not there, Panasonic FC, signal path Elna SilmicII( as per EW in earlier post on caps) Use t6he same uf numbers.

 

[Surgeon]

I was 19 when I purchased my first Spec components...

I was 21, going to college and working nights as an auto mechanic at a local Volkswagon/Porsche dealership. When I moved into my first appartment my stereo system consisted of a $20 car cassette player connected to a pair of 6" car door speakers & powered by a Radio Shack 12V power supply.

At the time I had a lot of friends who spent their entire paychecks on baggies of pot, while I instead spent mine on boxes of Pioneer (and smoked their pot!)...

When I bought my 1st receiver, a SX650, I was hooked! Then an upgrade to a SX850, followed by a SX1250. From that point on I switched to SPEC equipment and have had them ever since... And the speakers were another story. I remember having to save for over a year to be able to buy the Infinity QLS-1's. To this day I'm still in love with the absolute sound clarity that those speakers generate. (The only thing that even comes close is my Sennheiser HD650 headphones.)

I always tell everyone that I can't play any musical instruments, but I can play a mean tape-deck, so I purchased the best tape-decks & equipment I could afford at the time...

Lookin good Surgeon, kinda overkill on the heatsinks, but hey, whose project is this?

I want to do this now and have it last long enough that my grandson might inherit & get some enjoyment from it someday... And since I owe the tax people so much friggin' money that they can't/won't afford to let me die anytime soon, that means it has to work properly for many, many years to come...

-Surgeon-

 

[Surgeon]

Get yourself some insulating shoulder washers ... and electrically insulate those heat sinks, it's cheap insurance and GOOD practice.

I agree 100% that it is absolutely the best idea, but there is just so much heat transfer lost with even the best sil-pads. It's kinda like wrapping your body in a rubber suit smeared inside & outside with grease and then standing in front of a fan trying to cool off on a 100 degree day.

And since this is an old-school single-sided circuit board with lots of exposed bare wire via's anyway, I don't percieve that the heat sink extension wings pose much-if-any greater risk that the original 'electrically-hot' heat sinks did to start with. And the direct metal-to-metal contact (with just the thinest layer of compound) between the TO-220's tab & it's heat sink provides for a lot better heat dissipation solution, which is the main goal.

Again, I wish I could provide a full 3D CAD image so everyone can see that there is plenty of clearance! I could easily take a 1/4" drill bit between 99% of the sinks & their nearest components, and at least an 1/8" between the remaining 1%. The bare legs of the TO-220 transistors are a lot closer to each other than the heats sinks are to anything else, and I won't lose any sleep worrying about them shorting out to each other!

-Surgeon-

 

[Surgeon]

The problems you guys think your seeing with the additional heat sink wings is due soley to the 2D photos your viewing. In the "real world" you'd easilly agree that clearance problems are a total non-issue...

For example, in the top photo below you'll see that there's plenty of clearance between the rightmost heat sink & the 1st connection pin, but on the other hand the sleeved resistor appears to be almost touching the heat sink wings...

But when I rotate to unit to provide another perspective as in the bottom photo, it's obvious that there's absolutely no issue with the heat sink wings & the sleeved resistor at all...



Maybe these 2 photos will help demonstrate that the Heat Sinks clearance is really OK:

There's so much clearance in fact that if Pioneer had designed it this way to begin with no one would have ever second guessed it...

You remaining non-believers will just have to drop by and check it out in person... Bring beer...

-Surgeon-

 

[markthefixer]

You have been doing an excellent job, I was impressed, and my comments were meant to be constructive - not combative.
We do NOT take the "convince me and defend yourself" attitude on this board, yet somehow in the last few minutes I have felt the need to defend myself.

And just exactly where was that sage advice when I asked for it at the begining of this thread when I was ordering parts?!? :scratch2: :scratch2: :scratch2:

The sage advice was in same place the list of all parts you were ready to order was, locked up in wetware - nobody could say "hey, where's the caps??". plus I felt like this whole thread was a "pop quiz", two posts on the same day, and then 4 silent days later with NO indications of anything, and then: "I ordered parts...." In defense, I offer up ALL the parts lists I have posted in the past.
I could NOT offer up a "tried and true, been there - done that" spec 2 parts list, because I was deferring to and waiting for EchoWars (or ANYBODY else who had "hands on") to post the specific caps he has (/they have) used on the many spec's that have taken their turn on his bench.

Get yourself some insulating shoulder washers for the 4-40 TO-220 transistor screws
532-7721-7PPS to-220 mounting shoulder washers, 4-40 $0.29 ea


and some mica insulators:
534-4672 to-220 mica insulators $0.12 each...........

or a full mounting kit:
532-4880SG @ $0.91 with sil-pad insulator, screw, washer, lock washer, insulating shoulder washer & nut.
532-4880 @ $0.77 with thermal film insulator, screw, washer, lock washer, insulating shoulder washer & nut.

532-4990M @ $0.77 with mica insulator, screw, washer, lock washer, insulating shoulder washer & nut.

and electrically insulate those heat sinks, it's cheap insurance and GOOD practice.
I've taken to doing that whenever I can.

You did ask for suggestions, and this is the first it (insulating the heat sinks) dawned on me, since your first post inferred doing all the to-220's when a question was asked. It did take a direct question by EchoWars to figure out that you were using the on-semi 32 & 33's in those positions.

Let's hope you don't have to do any troubleshooting with all those live fins flapping all over the board. Getting around them will be fun, but when they are live, waiting to short something else out, they become far more significant. Like I said, good practice - as in dressing wires, neatness etc... icing on the cake. On humid days, 60 volts can HURT, especially if you brush it with a forearm or wrist.

And I included the sil-pads as a choice as I did list micas in two places. I grabbed a chunk of text.
I'm not prepared to discuss/defend thermal resistance of various insulating materials at this time, as I stick to mica mainly. When I have lower wattage situations, I do use berquist pads at times, but I'm pretty good keeping the goop off my fingers.

edit: as an example I offer up the early model sx-828 power supply as an example. It has two "T" heat sinks on to-220 power transistors, that hover over the other parts, and Pioneer did mount them with mica insulators and nylon screws ( the nylon was baked to fragility and has been replaced with two mounting kits.) to keep it "cold", and all the components in proximity to them had fabric covers over the exposed wires.

 

[goat67]

Before you install the board I would clean the pins on the connector with Brasso
They look pretty bad right now.

Looks like you are doing a good job. You are getting advice from two of the best I would pay attention to what they say.

Love to hear it when you get done and I will bring beer

I am an Infinity fan also. I always wanted a pair of the QLS1s

 

[Surgeon]

You have been doing an excellent job, I was impressed, and my comments were meant to be constructive - not combative.
We do NOT take the "convince me and defend yourself" attitude on this board, yet somehow in the last few minutes I have felt the need to defend myself.

Hey Mark & ALL,

I MOST CERTAINLY DID NOT in any way mean to put you or EchoWars on the defensive -- I KNOW from lurking here that you guys ROCK! (It's kinda like the photos 'cause somebody is seeing malace that's just not there -- e.g. the comment I directed to EchoWars about missing "sage advice" was absolutely 100% done purely in jest!!!

I MOST CERTAINLY DO truely appreciate, read, savor & digest every word that comes from you, EchoWars & all the other pros & pros-to-be here on these forums! I readily admit that I haven't a clue what I'm doing, which is why I asked for help and I want to do everything I can to encourage you guys to give it... (BTW - The reason I was 'missing' for those 4 days after initially posting was due to RWFDE ("real-world-family-distraction-effect") -- my father-in-law went into the hospital & is now scheduled for open-heart surgery on Thursday.)

PLEASE understand that if I come on strong defending my viewpoints & ideas that it doesn't in any way mean that I don't also accept, value & most assuredly welcome yours!!! I'm the "new guy" here so I have to try hard to impress you "regulars" that I'm worthy of your efforts to assist me...

-Surgeon-

 

[Surgeon]

Before you install the board I would clean the pins on the connector with Brasso
They look pretty bad right now.

I agree totally & since they appear to me to be silver plated I thought I would use a little jewerly cleaner to remove the oxidation & then coat them with a layer of DeOxit...

Love to hear it when you get done and I will bring beer

As a fellow Infinity fan you're welcome to drop by any time... Just like the Motel-6 man says, "We'll leave a light on..."

-Surgeon-

 

[markthefixer]

Your Father in Law will be in my thoughts and prayers for a successful, complication free surgery and comfortable complete recovery.

 

[Surgeon]

Your Father in Law will be in my thoughts and prayers for a successful, complication free surgery and comfortable complete recovery.

Thanks so much, Mark... We're sure he'll be fine... Some kind of valve problem... But it still puts little hobby projects like this one in their place for a while...

-Surgeon-

 

[EchoWars]

I try to assist others when I can, but I have plenty of my own battles to fight. To assume that any of my instructions are comprehensive and all-inclusive of everything you need to know is to stumble into a trap of your own devising.

I assisted lots of guys in the hand-holding step-by-step approach to fixing their gear through web posts here at AK a few years ago, similar to what Mark does now, only to see about 1/2 of them end in disaster for one reason or another (usually a failure to follow instructions or procedures, or misinterpretation of instructions due to a lack of technical knowledge, or maybe I just suck at instructing others). On more than one occasion I ended up repairing the unit for free, out of a sense of responsibility or guilt for the incident. I have since decided that I have to take care of my own issues first, and while I'll happily attempt to steer would-be DIY'ers in the right direction, I have long since abandoned the hand-holding step-by-step approach to assistance. I have no problem helping with suggestions and pointing out common issues and problems, but to my mind, someone who is interested in tackling a project like this can also educate themselves with the abundance of technical information available on the web. If that gets too deep for them to grok, then perhaps the unit belongs in the hands of a professional. And I hope none of this is taken the wrong way...with the work and effort I've seen thus far, you obviously have a great deal more common sense and a smidgen more technical ability than the typical 'Help Me!' DIY'er who stumbles in to AK asking for assistance.

RE: The electrolytics. Old caps are old...of all the electrical parts in an amp, only electrolytic capacitors have a ticking clock on 'em for lifespan. As to your particular amp, on the driver boards there are four electrolytic capacitors...C1, the tantalum 4.7µf 35V input cap, C4 the 10µf 50V AC bypass for the bases of Q2 and Q3, C5, the 10µf 35V bypass for the D2 34V zener diode, and C6, the 22µf 35V feedback DC blocker. I usually replace C1 with a 4.7µf 25V Elna Silmic cap, as I do not care for tantalum caps in the signal path. C4 & C5 both get a 47µf 50V Panasonic FC cap, which leaves only C6.

Because of the oddball way in which the protection circuitry works on the Spec 2, C6 is made as small as possible to prevent power-on thumps, as the bigger this cap is, the longer it takes to charge and the DC offset to settle when turning the unit on. But the stock 22µf value is a real compromise, and causes a lot more distortion in the bass region than necessary. On the first Spec 2's I rebuilt, I replaced this cap with a 470µf 10V cap (this part of the circuitry will never see more than a volt or two, so 10V is more than enough...the stock cap is a 35V cap probably through convenience). What I found is that the large 470µf cap took so long to charge that annoying thumps were heard on power-up. I eventually settled on using a 100µf 10V Panasonic FM, which still usually results in a mild thump on power-up, but unless connected to efficient speakers, the thump is usually not a problem. But I'd say that unless more radical changes are planned to the protect circuitry that this cap be kept to a maximum of 100µf, and perhaps even less if the power-up thump might be problematic...which is why I suggested a slightly smaller cap, such as a 68µf. Or you can stick to the stock values if you determine that 'what was good enough for Pioneer when they built the amp is good enough for you'.

Hope this serves to steer you in the right direction, as well as enlighten you a bit as to my so-called philosophy in lending assistance. It is not my intention to leave others in the dark as to what they should do, rather to help where I can and when I can, without usurping all my available time. Some things you simply gotta figure out on your own, which will further your skills a great deal more than the 'look here, do this, do that' approach.

Best of luck and well-wishes for your father in law.

 

[laatsch55]

I'm still amazed you devote as much time as you do EW!!!!

Surgeon, Having never heard a set of RS-1's in person I dont have an opinion, BUT, the purest , cleanest, with clarity that's hard to imagine was the Spec gear driving A pair of OHM Model "F" s. Bought new in 1979. As a tribute to the folks at Ohm Acoustics a short story is in order.
At the time I was into several different chemical substances, one of which allowed for very little patience. Trying to get the Ohm's as loud as my old 901's resulted in unwinding the voice coil from one of the speakers. Exhibiting the patience of Atilla the Hun i diseccted said speaker with an ex-acto knife to see what happened, I obviously blew it up. Boxed 'em up sent 'em back so Ohm could see what a tweaker with too much power could actually do. Thought nothing more about it. Six weeks later i received a brand new pair, no freight collect, no nothing, except a note that said " We're sorry Mr. Laatsch, you're speakers were shipped with 5 amp fuses instead of 4 amp, enjoy your new set!" They were out of warranty and I shipped the destroyed set back as a joke. Those Ohm folks were something else, so were the speakers. I was in no shape to appreciate them.
Hope your father -in -law does well.

 

[Surgeon]

I try to assist others when I can...

Based on what I've seen (and heard from many others on these forums) you do an ABSOLUTELY AMAZING JOB of helping everyone the way you do... I, for one, am very greatful (as are all the others I'm sure) and fully understand that this is NOT the 1-900-ASK-ECHO pay-for-technical-support-line... Quite frankly I'm awe struck, because I know how long it take me to formulate an intellegent question & get it typed into a message, while in the same amount of time you have often responded with answers to 20 different messages or more!

I know that sages like youself, Mark(thefixer), Laatsch55, and all the un-named others here, are mostly on the giving end -- which takes a special kind of person to be willing to donate so much of themselves for the betterment of others...

All I can say is THANKS SO VERY MUCH to you & everyone else for all the assistance, and hope that in a small way through the sharing of some of my novel thoughts, ideas, & discoveries that I may ocassionally send a few gems back in payment...

...with the work and effort I've seen thus far, you obviously have a great deal more common sense and a smidgen more technical ability than the typical 'Help Me!' DIY'er who stumbles in to AK asking for assistance.

That makes my head swell a few sizes coming from you... I only hope that I prove to be a worthy apprentice...

RE: The electrolytics. Old caps are old...of all the electrical parts in an amp, only electrolytic capacitors have a ticking clock on 'em for lifespan. As to your particular amp, on the driver boards there are four electrolytic capacitors...C1, the tantalum 4.7µf 35V input cap, C4 the 10µf 50V AC bypass for the bases of Q2 and Q3, C5, the 10µf 35V bypass for the D2 34V zener diode, and C6, the 22µf 35V feedback DC blocker. I usually replace C1 with a 4.7µf 25V Elna Silmic cap, as I do not care for tantalum caps in the signal path. C4 & C5 both get a 47µf 50V Panasonic FC cap, which leaves only C6... <SNIP> ...which is why I suggested a slightly smaller cap, such as a 68µf.

OK. A few question/observation about your excellent explanation of the caps on this amp...

C1 -- Using the 4.7µf 25V Elna Silmic cap is an perfect replacement since it's in the audio path.

C4 & C5 -- I'm confused here. These are simply (noise) bypass caps so I understand that the uf values aren't that important, but when I look at the schematic in the service manual it shows that C4 traces back to the power supply on a -31V(-75V) line & C5 traces back to the power supply along a +31V(+75V) line. (The values in ()'s represent full 250W @ 8ohms output). So why did Pioneer use a 50V rating for C4 & a 35V rating for C5??? Wouldn't under-spec'ing the caps voltage make them die sooner? (I'd really like to know your thoughts on if this under rating is a big deal or not...)

C6 -- Since it's function is R/C dependant, I like your advice about keeping it around the 68uf mark to keep the "thumps" down...



---- OK. Now for my "really strange" interpretation of your recommendations...

C1 -- Use the 4.7µf 25V Elna Silmic cap absolutely!

C4/C5/C6 -- Why not just keep it really simple and replace all 3 with 56uf/50V caps? By keeping all the values the same you can get to the quantity discounts quicker & don't even have to think twice about which-goes-where... Your recommendation of the Panasonic FM series (DigiKey Part# P12928-ND) is very good, as they have a long lifespan of 2000hours@105°C. But the Nichicon HE series (DigiKey Part# 493-1604-ND) has 2.5 times the lifespan of the Panasonic's at 5000hours@105°C, so why not use those instead?

Best of luck and well-wishes for your father in law.

Thanks so much...

 

[EchoWars]

C4 is on a voltage divider. The voltage in the cap is [15K/(15K + 33K)] x 91V = 28V & change. C5 is hitched across a 34V zener diode, so the voltage there has to be about 34V. A 56µf 50V cap is fine, although 56µf is an oddball value, but is available in a HQ cap, such as the Nichicon HE. Note that both of these caps also have to charge before the input stage settles, so increasing the size is also flirting with turn-on thumps. If you're especially averse to these thumps, consider changing them out to a maximum of 22µf.

Electro Caps work best when the voltage on them is about 75~90% of their voltage rating. A 50V cap for C6 is simply inappropriate, as this is probably the most important cap on the board. 10V is more like it. I can't find a quality 56µf cap for this position. A 47µf 10V Panasonic FC, or (better for this job) a 47µf 10V Nichicon PW (#493-1732-ND, Digikey).

 

[laatsch55]

Surgeon, much as I would like to be mentioned in the same breath as Mark or Glenn in tech prowess I'm not even close. My forte is oilfield production equipment, pumping units my speciality. I know my way around a soldering iron and can follow directions and to some extent operate autonomously. I just fixed my Spec 2 before you did.

 

[Surgeon]

Surgeon, much as I would like to be mentioned in the same breath as Mark or Glenn in tech prowess I'm not even close

I understand that Mark & Glenn are the true 1000W Electronic Generals around here, but I'm also sure that a newbie PFC like myself can still learn a thing or two from all the Sargents and Corporals as well... It's the fact that you make the effort to try and assist others that I was praising... :thmbsp: :thmbsp: :thmbsp:

(And thanks for the kind words before for my father-in-law...)