SX-1010 project

I'm so close to placing my mouser order and begining my recap. I just need to find a replacement for Q1 and Q7 on the power supply. Seems MJE15032G is out of stock everywhere I look.

Is their no alternate part that I can use for this transistor?
The SD313 is a 60V, 3A device and the 15032G is a 250V, 8A device. So anything larger that 60V, 3A should work. You could sub a MJE15030G which is 150V, 8A or go higher and sub a MJE15034G which is 350V, 8A.
 
I now have all of my parts, and I think that I have the unit as clean as it's going to get. I've given it a couple of simple green baths using a soft paint brush. For the second wash I diluted the mix more to try to keep the simple green smells down. We have had lots of low humidity warm sunny days lately that I have been able to take advantage of. I have been able to wash, blow dry with air, and then sun dry. The difference between before and after is surprising! I'm very happy with how much it cleaned up.

I'm getting everything set to begin the restore. I'm thinking of starting with the power supply board and then the protection circuit. I also have a new protection relay that I'll install. I assume that I will still have the same issues as I did on the initial trials but at least I'll know my power supply is working correctly, and I'll have a properly functioning protection circuit. At that point I can move onto the amp boards where I suspect my offset and bias issues may lie.

Please let me know what you guys think.

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Looking good, be careful with that power supply board, before you flip that board over to work on it cover those rectifiers with a towel, they can be live.
 
Ok guys, I have been working on the power supply board and I could use some input regarding diode D7.

Before doing anything at all to the PS board I noticed that D7 would give a continuos beep from my multi meter using the diode checker setting. I also got the same results when the meter probes were reveresed. D7 gave the same results with the multi meter after replaceing all of the electrolytic capacitors including C20 and C21.

Today, I replaced all of the diodes D1 - D7 with new diodes. The original D7 diode tests fine now that it’s out of the circuit, but the replacement diode gives the same continuous beep from the multi meter now that it is solder into the circuit.

What I am wondering is, is this indicating another issue in the circuit or is this expected due to the D7 diodes placement in the circuit? I don’t know enough on my own about the actual circuit design to be able to determine if this is an issue or not. Is it possible that C7 has failed and is causing this result? Or is this the reading I should be getting when testing this diode in circuit?

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c7 is short circuit

Thank you for the feedback. This is what I suspected, but the weird thing is that C7 does not show any visual signs of failure. From the outside it looks the same as the others. I figured it would be best to ask the question here before replacing more parts.
 
I went ahead and pulled C7 out. It tests fine out of the circuit. It is not shorted. D7 still gave the same result even when C7 was pulled out of the circuit.
 
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After looking at the schematic some more I noticed that pin 5 and pin 6 on the power supply board run to the dimmer switch on the front panel. I moved the dimmer switch button to the other position and the D7 diode tests fine.

Sorry about that. At least I figured it out. Looks like I’m good to keep moving forward here.
 
Great work so far! Keep it up. I like how well it cleaned up.

Thanks Loweran. I was feeling a bit bummed when I first opened it up and seen how filthy it was. I got it for a nice price so I couldn’t be too upset. I am also very happy with how it cleaned up.

I’m taking my good old time with the PS board. I’m sure the rest of the boards will go faster once the PS is done. I also have the 737 to listen to now so no need to rush. Slow and steady with this one.
 
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Finally life has slowed down some and I have been able to get back to work on the power supply board. I had a very busy fall this year. At this point I have replaced all of the capacitors and diodes, and I have also replaced several resistors.

Today I have been working on replacing transistors and I have found a descrepency between the service manual and the silk screen on the PS board for Q5 and Q6. 2SA628A. The silk screen shows this as a BCE but the service manual shows it as an ECB. Can someone please clarify what the pinout is for 2SA628A?

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Hi, the 2SA628A is BCE as shown on the silk screen (the silk screen is correct), the service manual has is wrong.
 
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