Pioneer SX-1980 80v Regulated Heatsink Preliminary Drawings

[rcs16]

You can use fairchild as a sub for MJE1503x, look to be better specs too!!
I have only ran sims with them but they seem to perform better in sims than MJE1503x, but it is only sims!!
FJP1943
PNP Epitaxial Silicon Transistor
Applications
•High-Fidelity Audio Output Amplifier
•General Purpose Power Amplifier
Features
•High Current Capability: IC = -15A.
•High Power Dissipation : 80watts.
•High Frequency : 30MHz.
•High Voltage : VCEO= -230V
•Wide S.O.A for reliable operation.
•Excellent Gain Linearity for low THD.
•Complement to FJP5200
•Full thermal and electrical Spice models are available.
•Same transistor is also available in:
-- TO264 package, 2SA1943/FJL4215 : 150 watts
-- TO3P package, 2SA1962/FJA4213 : 130 watts
-- TO220F package, FJPF1943 : 50 watts

 

[EchoWars]

The FJPFxxxx parts are out of production.

The On-Semi MJF15030G and MJF15031G are insulated 150V 8A parts and in current production, and 30-something watts when big heatsinking is applied. Problem is, no one has the MJF15030G in stock...backordered everywhere.

I'm getting some TO-220 sockets to make things easier to deal with, and mount some regular MJE15032G and MJE15033G parts to the big heatsinks w/mica and a shoulder washer and see how that goes.

 

[zebulon1]

Do you have a P/N for just the shoulder washer? I can find the mounting kits all day but not just the washer alone.

 

[EchoWars]

532-7721-8PPS
or
532-7721-7PPS (Mouser)

The first is a little larger with a flat on one side. That's the one I'm using

 

[zebulon1]

Perfect! Thanks

 

[rcs16]

Sorry, I did not check stock avail, not too much to select from at Mouser in a isolated TO-220 pkg. 2sc4793 is non-isolated and only 1A rated, not so good for this app.
http://ca.mouser.com/Semiconductors...0y4ciZ1z0z63xZ1z0y4diZ1z0y4cnZ1yx61b3Z1z0xn56

 

[EchoWars]

Yeah, it's too bad. The FJPF parts were pretty badass for TO-220's.

 

[zebulon1]

Hey, You have to check out this Ebay listing! No affiliation!

http://www.ebay.com/itm/VINTAGE-PIO...pt=Vintage_Electronics_R2&hash=item1c46b2c1d8

 

[rcs16]

Notice the fan mod? and still, they blow up
Want to venture what it will go for?, I am guessing $750-1000, now how do you guarantee it makes it in one piece, pickup!!
Anyone live close to Magnolia, Kentucky?

 

[SolderIron]

Experience tells me depending on the fan is asking for trouble unless there is a stuck/stop fan alarm.

 

[zebulon1]

The larger sample TO-220 heatsinks are on the way and the quote for the modified bottom cover is $78.00. Its made as the original. Same thickness (0.49), metal, unpainted with double the venting. That was for 20 pieces. I could get a better pricing if I went to a larger quantity (20 is alot in this business. I know from experience ). The $78.00 is the actual cost. Powder coating will cost an extra 15.00.

 

[jbrainey]

The larger sample TO-220 heatsinks are on the way and the quote for the modified bottom cover is $78.00. Its made as the original. Same thickness (0.49), metal, unpainted with double the venting. That was for 20 pieces. I could get a better pricing if I went to a larger quantity (20 is alot in this business. I know from experience ). The $78.00 is the actual cost. Prouder coating will cost an extra 15.00.

I know it is not reversible but, wouldn't it be cheaper to modify the original cover with more venting? That would be my preference. Then you wouldn't have to worry about losing the original cover and you could still call it original.
Regardless, I have a candidate for restoration and/or modification with these upgrades. I just need a tech willing to take it on sometime in the foreseeable future along with a SX-1250. Please.

 

[onwardjames]

For the armchair readers that are wondering why this thread exists at all---
There are several Pioneer receivers that run %*&^ hot in use, and I mean HOT. Think class A hot, tube hot, usually due to pushing the limits for the time in power supply design. The most guilty culprits are SX-1010 and sx1980 with their upside down on the bottom power supplies followed by the sx1280 which thankfully has a vertical board. No big deal you think, they designed them that way. Ok, you are correct however if you look at most of the threads on these units you will see that in most cases the failure issue revolves around a cooked power supply. When we rebuild them and put our reputation on the rebuild the last thing we want is a unit left running for 12 hours a day slowly baking itself again followed by unhappy correspondence down the road. The possibility of board fracture is very real on both the 1980 and 1010 and has doomed many a shipped unit through the years btw. I a new bottom cover specifically for the 1980 was made with @ 3/4 inch drop around the power supply board area many other cooling options would present themselves.
Oh, btw its not just a Pioneer thing.
-Lee

Thanks for clearing this up for the non technical of us.

I bought Zebulon's Sx1010 he reworked, modding the easy-bake oven part of it, and it works cool and clean.

Keep at it fellas, tho I don't know all you guys speak on, I enjoy reading it.

 

[onwardjames]

Anyone live close to Magnolia, Kentucky?

I live in Bowling Green, Ky...

 

[markthefixer]

I looked into that SX-1980. The phono amp is unshielded and remounted centered under the tuner. He said that there wasn't much dust in it.
With the opposed cooling fan and presumed hole, the airflow is cross chassis and the power supply area does not benefit.
It was a relatively neat job from the pictures.

 

[zebulon1]

MTF, Whats your thoughts on the bottom cover?

 

[markthefixer]

I don't think it's a good idea to re-engineer the whole airflow plan with a revised bottom plate, but rather do what you initially set out to do, increase the air to heat sink area and get it into airflow. We have absolutely NO idea how diligent or negligent they were in their airflow routing, flow restriction considerations as well as heat exchanger design.

I try to observe the principle of "KISS" - Keep It Simple, Stupid"

Considering the price, versus the potential benefits, of a different bottom plate, it just isn't worth it. We will be better off just unshrouding that 35% blockage of the 10 x 20 vent hole caused by the +/- 80v regulator's heat sink.

 

[craxx6969]

My bad, thought I saw a 1980 but it was a 1280 that was beat up.

 

[zebulon1]

The sample heatsinks arrived this afternoon.

They will need to be drilled and tapped and I am waiting for the plastic insulating bushings for the TO-220's.

The HS's may seem shallow but the clearance is tight from top to bottom. We still need the space to add the top plate. What the HS lacks in height it has in depth.

My plan is to check the temps with only the new HS installed and then look at adding the additional top HS plate.

I will have a before and after temp chart.

 

[zebulon1]

Doing the temp measurements on the original heat sinks for the 13.5v regulator Q203 and the 8v Q205. They topped out at 190.1 F., after 10 minutes.

The original Pioneer duel heatsink for the +- 80v regulators Q210 and Q211 topped out at 151.1F.

It didn’t matter where on the HS I located the probe, the temps changed little. I had the set on its side with the bottom cover on for the entire temp measurements. I had thought I might position the set in the normal operating position but decided to leave it on its side. Moving it around is a total pain as I do not want to damage it. Taking the temp measurements is going to be a comparison to the modified HS’s so I will reproduce the setup the same on each mod attempt.

The results show that the Duel +- 80v Pioneer HS only gets to 150F which it first seemed like it was the hottest heat source. As it turns out, the smaller regulators with the separate HS’s, are the hottest by 40F over the duel HS.