Pioneer SPEC 2 restoration help

Sorry Mark, I'll be more thorough next time!

I was just worried, since the thing does come in two different lead layouts... which in the past I hadn't stressed.... and I am correcting MY error

So I got ALL the information on the product's codes out....
 
For Blue Shadow: I am impressed. Unfortunately, my SPEC isn't in as good a shape as your pre-restoration Kenwood was. Rust is rust and hard to clean. First time I've seen it on board components this bad as found on my SPEC. I do have a challenge on my hands.

For EchoWars: Regarding the US Relays (Digikey) relay to be installed on the SPEC PA board...Digikey minimum buy is 15 pieces. Am I reading this correctly on their website? I'm ready to order parts now. I am also looking to replace the TO-3 sockets with parts from Digikey if I can't clean the original Pioneer sockets. Will this Digikey part (4601K-ND) work?

Thanks.
 
For EchoWars: Regarding the US Relays (Digikey) relay to be installed on the SPEC PA board...Digikey minimum buy is 15 pieces. Am I reading this correctly on their website? I'm ready to order parts now. I am also looking to replace the TO-3 sockets with parts from Digikey if I can't clean the original Pioneer sockets. Will this Digikey part (4601K-ND) work?
Looks like the US Relays part is going to be dropped by Digikey...I have no idea why. When I ordered mine, there was no minimum. They do still have the Z532-ND relay available, which is essentially identical to the other part number I gave and will work fine. Digikey shows 900+ of these in stock, but it looks like they too are being dropped once stock is gone. Once that happens, the Hamlin HE3300 24V SPST relay can be used. Part #HE129-ND.

4601K-ND is a transistor mounting socket, so I dunno what you were looking at.
 
For laatsch55 and/or markthefixer:

I'm a little confused by posts 57-60. Is the Fairchild KSA992 (F or P) a good sub for the 2SA872A's? Is Mouser the source for these (in case I don't have time to do the search myself)?

If Mouser has the 2SC945's, are they the reliable source? Otherwise, which Fairchild part ended up being the correct sub for the 2SC945? I'm a little confused by posts 58 and 60.

Thanks.
 
I know of NO source for decent TO-3 sockets, since everybody is phasing these devices out slowly but surely. Those Keystone sockets are pretty crappy.

Why do the sockets need replacing? You need to do anything and everything you can to keep the original sockets in that amp.
 
For Blue Shadow: Oh, Ok. I'm still impressed, though.

For EchoWars: Alright. I'll do what I can for the originals. My issue...rust, rust, rust. Everywhere. I hate rust (especially on stereo equipment). People who store nice stereo equipment (it doesn't have to be Pioneer, either) in damp basements, attics, outside storage sheds, garages, etc. for 20 years ought to be strung up by the short hairs. Sorry, my pet peave. Hope I didn't offend any AK members.
 
For laatsch55 and/or markthefixer:

I'm a little confused by posts 57-60. Is the Fairchild KSA992 (F or P) a good sub for the 2SA872A's? Is Mouser the source for these (in case I don't have time to do the search myself)?

If Mouser has the 2SC945's, are they the reliable source? Otherwise, which Fairchild part ended up being the correct sub for the 2SC945? I'm a little confused by posts 58 and 60.

Thanks.

2sa872 pnp ecb 120v 50ma .3w 250-800hfe 120mhz
can be replaced by
512-KSA992FBU (ln)to-92 pnp ecb 120v .05a .5w 100mhz 150-800hfe $0.05 ea
and here's it's complement:
512-KSC1845UBU (ln)to-92 npn ecb 120v .05a .5w 100mhz 150-800hfe $0.05 ea

the 2sc945 to-92 npn ecb 50v .1a .25w 150mhz 90-600hfe
is directly replaced by:
512-KSC945CLTA to-92 eCb 50v .15a .25w 300mhz 40-700hfe $0.05 ea
or with a DIFFERENT PINOUT:
512-KSC945LBU to-92 eBc 50v .15a .25w 300mhz 40-700hfe $0.05 ea
....
and the complements are:
512-KSA733LBU to-92 eBc 50v .15a .25w 180mhz 40-700hfe $0.05 ea bu = bulk
or with a DIFFERENT PINOUT:
512-KSA733CLTA to-92 eCb 50v .15a .25w 180mhz 40-700hfe $0.05 ea ta = ammo strip
 
Slipstream55,

I too am in the middle of a repair on my Spec 2. I had ordered 15 of the Read Relays (Z535-ND) from Digi-Key and found out the lead time was around 10 weeks. I was reading through this thread today and noticed EW had suggested the Z532-ND so I called Digi-Key and cancelled the prior order and change to the 532 version. I am close to getting through my repair/recap. Hopefully we will both be happy campers after the work is done.

Ray
 
For EchoWars or markthefixer:

Do you have a replacement part and source for RL1/RL2 on the SPEC-2 Power Supply board and RL2 on the PA board?

Thanks for your help.
 
The two side-by-side relays on the power supply board are Omron LY2-0-DC24 jobs. Link to Digikey PN here. These relays engage the two different secondary transformer winding, depending on whether you select 8 ohm or 4 ohm at the rear panel.

RL2? PA board? Power amp board? Driver board. This is a 24V DPST reed relay that switches in the different current limit resistors depending on whether 8 ohm or 4 ohm is selected. I do not know of a direct replacement.
 
All of the parts I need to rebuild/recap the "Driver" boards and "Power Supply" board are on their way. Now I'm off to the UK to hunt for replacement metric hardware for the SPEC, enjoy some good English beer, bangers and mash, fish and chips and anything else I can find that sounds good.

If I'm real lucky, maybe I'll find the elusive STV4H and STV3H-Y diode packs while there.

Cheers.
 
The STV-3H diode is available from PartStore: http://www.partstore.com . I didn't know you needed one. The wait can and will be lengthy, but you can get them.

Something which Markthefixer and I have briefly touched on is that, in the original circuit, the D4 diode, STV-3H, is the one used to bias the output stage. The D11 diode, the STV-4H, is simply used as a shunt to bypass the D4 diode and the bias adjust pot...essentially acting as a 'bias limit' diode. It also protects the output devices in the case of the bias pot opening up.

spec2biasorgjs0.png


Simply put, the D11 STV-4H diode limits the bias adjustment range by imposing an approximate 2V limit on the voltage that can be generated between the collector of Q5 and the collector of Q7.

Well, let's see...there's another device that can force a nearly-steady voltage between two points: A zener diode. The Panasonic MAZ4020 is a 2V, 370mW zener diode in a DO-34 axial package. It's characteristics may not match the original diode to a 'T', but as far as acting as a 'safety-valve' in the case of a failed trimpot, it should work fine. (Digikey PN MAZ40200LFCT-ND)

spec2biasmodbb1.png


Note that the anode and cathode are reversed as opposed to the original STV-diode in order for the zener to perform properly.

The DO-34 axial package can even be mounted fairly easily by covering the leads with tiny shrinkwrap, and a very small ring terminal (such as the #5 hole ring terminal A27150-ND part from Digikey). The wire insert section can be straightened out and hammered flat, and the diode attached using JB Weld, which is a good conductor of heat.

Certainly I've never tried this, but I see no reason why it shouldn't work. I'd want to monitor the bias over a range of heatsink temperatures, but if it all looked good, I'd call it a done deal.

Edit: I meant to mention that, on many Spec 2 driver boards, one of these diodes (D4 or D11) has the silk-screening backwards...I cannot specifically remember which one. Check the orientation of the diodes currently in place before anything is removed. Do not rely on the silkscreening to get it right!

Edit #2: I'd be tempted to add a small film cap (such as a Panasonic 0.56µf 63V stacked film) across the zener to counter the effects of the dynamic zener impedence with AC signals. I'm not sure if it is important here, but it couldn't hurt anything. The cap will essentially perform an AC short from the collector of Q5 to the collector of Q7, and can be added to the back of the driver board (so no hassle with trying to remote-mount it physically with the diode).
 
Thanks for the information, EchoWars. This is important and the theory makes a lot of sense. Thanks, also, for the note on the bad silk-screening. I was going to verify the diode orientation before removing it (them) but I will check for this.

I wanted to replace the hack-job STV-3H with a real one on the one driver board that was "repaired" by the previous owner. I'll get some on order from the Parts Store. If I can't locate a STV-4H I will make an attempt at fabbing one that is a little better than what is on there right now.

Regarding paint and the SPEC top, bottom, and side covers...there are a few rust removing products available that purportedly don't affect (or have little effect) on the existing paint. I would try one of these and report on the outcome. I think a local auto-paint supplier near me may be able to match the color and texture/finish of the original Pioneer SPEC paint.

I would like to replace the power cord but I can't verify what gauge the wire is. If you know or have done this, let me know, please.

Well, T minus 11 hours and counting before my First Class ride to the UK (it was a free upgrade from Business Class on BA). Can't wait.:banana::banana::banana:
 
T-minus 4 hours and counting and...Holy capacitor Batman...

The wife just brought the mail in and, guess what? She's carrying three packages (Mouser, Digi-Key, and Electronic Surplus). Everything I ordered to start the SPEC-2 rebuild AND I CAN"T DO ANYTHING WITH THEM (for 9 weeks). ARRRGGGHHHH!!!:tears::tears::dammit::bash:

How does that go...Absence makes the heart grow fonder?

B#ll Sh*T.
 
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