Pioneer SX-40 Tube amp Power Capacitor picture please

[nongrata]

I bought defective Pioneer SX-40 tube amp with power capacitor C83 and C84 removed in it.
These 2 Capacitors are 100uf 180Volt grey Elna's.
From this models you do not find any pictures of the wirings and components on the internet.
Can anyone please help me and post a picture so I can see how the wires (and diodes)
are connected to those 2 capacitors ?
I tried to connect them but would rather check with a picture if I did it right.
I am afraid if I made a mistake I might blow upon something beyond repair.

 

[Dandy]

Is this a tube amplifier? Google comes up with solid state amps with this model number.

 

[primosounds]

It might be a "voltage doubler" circuit. Checkout the Fisher models of later vintage that mostly use solid state rectifier in a voltage doubler. if this is a SS amp i think you should ask the guys in that forum.

 

[nongrata]

Yes it is a tube receiver. Everthing is handwired. EL84 tubes.made in 1964-67

 

[primosounds]

Yes it is a tube receiver. Everthing is handwired. EL84 tubes.made in 1964-67

So, without a picture of the part you are worried about we are just guessing. But, if this unit doesnt have a tube rectifier then it it could be a voltage doubler circuit. Although the cap values seem low. For units like your , pp el84, i would probably use 250 v x 200 uf or more.

 

[Dandy]

Okay, it's the amp version of the SX-82, which I have. http://www.hifimuseum.de/2147.html

The SX-82 uses a voltage doubler circuit, with two 100uF caps rated at 250V supplying the B+ of 450V. The SX-82 runs 7189 tubes, so maybe higher B+ voltage than the EL84s in your SX-40. Still, I wouldn't go below 250V for those caps. The wiring will be similar to that of the SX-82. Here's a small schematic of this one: http://epweb.tripod.com/webonmediacontents/sx-82 schematic.jpg

 

[nongrata]

I found a schematic and the elco’s are both 100uf 180v in it. I put in 150uf 450v. But i am not sure i connected them correctly. That is why i hoped someone might be able to post a picture how to connect them. I got the receiver with those capacitors removed.The wires (several) to connect to the elco’s are like spaghetti

 

[Dandy]

Can you not read the schematic?

 

[Dandy]

This should show you the orientation of the diodes and polarity of the electrolytic caps. The line going off in the top left corner under L10 (not shown) is the B+ to the output transformers' centre taps.

Because this is solid state rectified, if you have a variac, you can check your wiring with a low input voltage, e.g.10% of 120V to see if you get 10% of the expected B+.

 

[grindfix]

Here is the schematic and component layout of SX-40
Post a picture of what you are dealing with. I believe those 2 capacitors are 350 volts, All other cans are multi-sectional This receiver's wiring is real rat's nest PITA

 

[grindfix]

They were 180v and I re-stuffed them with 350v caps

 

[larryderouin]

The Plate voltage is something like 255V (fuzzy enlargement so I could read.) And that B+ comes off the +side of the VD. The other end of the transformer winding is pushing the tuner which might be something like 150-160V. Which would account for the original 180V can caps.

Nongrata. Please take some pictures of the power supply area (close ups and from different angles). Isolate the TWO WIRES Coming From the Transformer and Wrap with Masking tape so we can ID them. Write PWR on them. Then go over to the output transformer and locate the one wire on the transformer that comes back to the power supply. Mark it with tape and write OPT on it. Then locate the wire going to the Tuner (there should be a Coil near the pwr supply (I can't make it out on the schematic that Grindfix supplied) that the wire comes from) and wrap with Tape and Mark TUNE.
Take pictures of all this and we'll help you get it all connected right.

This is done on Paint and I can't draw for shit with a Mouse. So excuse it but it's functionally correct to the schematic.


This is approx what it will look like inside see note below.

 

[primosounds]

Here is the schematic and component layout of SX-40
Post a picture of what you are dealing with. I believe those 2 capacitors are 350 volts, All other cans are multi-sectional This receiver's wiring is real rat's nest PITA

the detail on the schematic you posted is too poor to see the part numbers and other pertinent data. But it definitely shows a voltage doubler circuit. Also the top part of the circuit shows a FWBR, full wave bridge rectifier, There are also power supply caps associated with this. But i can not make out the part numbers or values. Since the original caps were of an value that seems out of place with the voltage doubler supply, could the 2 caps of 100uf x 250v that you referred to in the first post be part of this circuit?

 

[nongrata]

First of all I want to thank everyone here who tried to help me out. Saw all this post here this morning (I live in the Netherlands in Europe) and was surprised to see so many replies.
I checked the drawings of Larry and It seems I connected the wires also like that (i tried to follow the electronics schematic I have from the SX-40).
Here some pictures and a drawing that might give you more insight how i connected the wires. Strange thing is that in the user manual the capacitor near the choke coil is C84. However the way I connected them according to the schematic the one with all the 3 wires (black) that go to ground or other minus connections is like C83 in the schematic.
So C83 is near the choke coil the way I connected it.
I did not put voltage on it yet. Do you think I should give it a try.

 

[nongrata]

Here some more. The red wire near the 133v goes to the diodes.

 

[grindfix]

My schematic file is not great but it zooms much nicer then in forum. I can PM my file. OP may have better copy anyways.
I found couple of pictures that I took before removing original cans. Pictures attached.

 

[nongrata]

Thanks for placing the pictures grindfix. I see a big grey elco that is above the power supply elco of 100uf 180 volt that is fascinerend the front of the receiver. I do not have it in mine. Looks the someone removed it when they removed the power caps. There is also one near the transformer (Nippon chemical brand) that misses in mine. So need to dig info that also.

 

[Dandy]

As Grindfix and the OP have the correct schema and access to pics, I'll step out of this discussion. However, it has reminded me what a PITA the wiring of this receiver is. Also, it's reminded me of having to replace all the PIO caps as well as the electrolytics and some other caps. Also many of the resistors in mine were way off.

Nongrata, if you haven't done so, plan to replace all the caps. I attach a closeup of the voltage doubler in my receiver and an overview showing all the replacement caps.


You might find it useful to glance at my SX-82 thread and the link to the work done by LinuxGuru. http://audiokarma.org/forums/index....acing-noisy-resistors-in-pioneer-sx82.716969/

 

[grindfix]

I sold my unit after re-stuffing C84 & C85 cans. Guy who bought it is doing full recap and he found several resistors out of specs, including one in the biasing of right channel preamp tube which, of course was affecting the balance between the channels. I did not want to continue with such a difficult example to work on. It was blowing fuse due to one of those caps shorted. I got it going and got an idea on the sound and power level and decided to sell it. New owner seems to get it under control.

 

[Dandy]

I've just been running mine, as I had dragged it out of storage. Man it's heavy. It can sound nice, but way too many features on the controls that I suspect degrades the sound. I had to replace quite a bit of the power amp to get the biasing right.

Still these are late sixties tube amps, at the end of the tubes era for Japan and are loved by some collectors. Nongrata, I hope you are soon enjoying yours.