SX1980 Power supply board ...... OH NOOOOOOOO!!!!

It can be an original doorstop, or a working unit with a lot of modern transistors and caps. The market has determined that WORKING is the breadwinner.

For current source stuff, find the sx-1980 threads by anderslober in the pioneer audio forum, it has GOOD, annotated pictures of what's removed and what's added.You're in some of the threads too, so you should remember a bit.

Ah yes I do remember that thread, I think a stumbled across it before, I figure I need to do it as one of the 2SK34's has been ejected before I got to it....I read EW's thread from 2007 in DIY Audio as he developed it. Great reading!!

This is good, a plan is formulating, this is one SX1980 that will not end up a door stop or boat mooring...
 
Ah yes. They Exist here in Sydney at Sth Granville actually.
I was going to mention them, but didn't think you'd heard of them.
If your company has an account then you'd probably enjoy a decent discount.
Excellent ! :thumbsup:
I'll be watching this thread. Very interesting stuff even though I don't have a 1980. I'd love to some day though...... yeah dream on ......
I have a different view, after decades of wanting one (and never seeing one locally ever) but reading every 1980 thread, I dunno if I ever want one....TOTTOTL machine, but slightly more a pain in my ass than working on my northstar...thru the firewall. Good luck on this project.
 
I'm getting ready to install a set of these Desk Top cooling fan extensions for EW's remote regulator mounting mod.
The 12" extension is a little too short for mounting Q204 and Q203.
The mod is discussed "Here" if you haven't seen it:

DSC03987.JPG
 
I'm getting ready to install a set of these Desk Top cooling fan extensions for EW's remote regulator mounting mod.
The 12" extension is a little too short for mounting Q204 and Q203.
The mod is discussed "Here" if you haven't seen it:

Yes I will be doing this I have studied that thread, but I'll remote mount the +/-80V regs only, once the board is less cluttered etc etc theres enough room to mount better heat sinks on the other regs...

I also have a bunch of 3pin molex connectors which perfectly fit TO220 devices, so I'll use those, I have them in stock.
 
I have a different view, after decades of wanting one (and never seeing one locally ever) but reading every 1980 thread, I dunno if I ever want one....TOTTOTL machine, but slightly more a pain in my ass than working on my northstar...thru the firewall. Good luck on this project.
Pfft......bit of re-engineering the PSU board and job done, better than new........I'd have one no doubt about it....
 
Right, time to clean this thread up a bit so it may be of use to others.
This is mattsd's list for the AWR154, so I am posting here to check in with the resident experts.
AWR-154: C203: 3300uF 35v CEB: 647-TVX1H332MDD 3300uF 50v
AWR-154: C204: 220uF 160v CEB: 647-TVX2C221MDD 220uF 160v
AWR-154: C205: 220uF 160v CEB: 647-TVX2C221MDD 220uF 160v
AWR-154: C210: 100uF 10v CEA: 647-UPW1E101MED 100uF 25v
AWR-154: C211: 100uF 16v CEA: 647-UPW1E101MED 100uF 25v
AWR-154: C212: 100uF 10v CEA: 647-UPW1E101MED 100uF 25v
AWR-154: C213: 100uF 6.3v CEA: 647-UPW1E101MED 100uF 25v
AWR-154: C216: 100uF 50v CEA: 647-UPW1J101MPD 100uF 63v
AWR-154: C217: 100uF 50v CEA: 647-UPW1J101MPD 100uF 63v
AWR-154: C218: 10uF 50v CEA: 647-UPW1J100MDD 10uF 63v
AWR-154: C219: 10uF 50v CEA: 647-UPW1J100MDD 10uF 63v
AWR-154: C220: 100uF 100v CEA: 647-UPW2A101MHD 100uF 100v
AWR-154: C221: 100uF 100v CEA: 647-UPW2A101MHD 100uF 100v
AWR-154: C222: 100uF 50v CEA: 647-UPW1J101MPD 100uF 63v
AWR-154: C223: 100uF 50v CEA: 647-UPW1J101MPD 100uF 63v
AWR-154: C224: 100uF 50v CEA: 647-UPW1J101MPD 100uF 63v
AWR-154: C225: 100uF 50v CEA: 647-UPW1J101MPD 100uF 63v
AWR-154: C301: 100uF 16v CEA: 647-UPW1E101MED 100uF 25v
AWR-154: C302: 100uF 16v CEA: 647-UPW1E101MED 100uF 25v
AWR-154: C303: 47uF 16v CEA: 647-UPW1E470MDD 47uF 25v
AWR-154: C305: 10uF 16v CEA: 647-UPW1E100MDD 10uF 25v

Q201: 2SC945: 512-KSC2383YTA
Q202: 2SC945: 512-KSC2383YTA
Q203: 2SD712: 863-MJE15032G
Q204: 2SC945: 512-KSC2383YTA
Q205: 2SD325: 863-MJE15032G
Q208: 2SC945: 512-KSC2383YTA
Q209: 2SA628: 512-KSA1013YBU
Q210: 2SD712: 863-MJE15032G
Q211: 2SB682: 863-MJE15033G
Q212: 2SC1318: 512-KSC2690AYS
Q213: 2SA720: 512-KSA1220AYS
Q214: 2SC869: 512-KSC2383YTA
Q215: 2SA628: 512-KSA1013YBU
Q216: 2SD325: 863-MJE15032G
Q217: 2SB536: 863-MJE15033G
Q301: 2SA872: 512-KSA992FBU
Q302: 2SC1438: 512-KSC2690AYS

D212: EQA01-35R 35V 1/2W zener: 512-1N5248B and 512-1N5247B in series
D213: EQA01-35R 35V 1/2W zener: 512-1N5248B and 512-1N5247B in series

I am researching more about the current source mod, seems there may be two different circuits floating around here, Marks one and EW's one.
I have EW's circuit diagram, but no parts list, I have a parts list for the other one (I think) but no diagram...
I am continuing to research this out some more.

Here is the parts and information for the replacement of the relays.
S1: Relay (Soft Start) ASR-046: 653-LY1-0-DC24 (Achtung! Using this relay requires you to remove R102 and run a jumper wire from the + terminal of the 3300uF 35v axial cap over to the pad of R102 that connects to pin 2. Be very careful, if you put it to the wrong side of the R102, you will short the 24v supply to the 100v supply. Not good. To be extra safe, you can just remove R102 and connect the jumper wire straight to pin 2)

S2: Relay (Protection) ASR-048: 653-MY2-02-DC48
 
The TxTurbo board is a drop in and works like a champ. On the other hand the original board can be rebuilt with the current source mod and will also work well and run cooler than the original design once you remote mount those four transistors. Figure on twenty hours in labor to rebuild it though if you work at the same pace I do---
I have used Mark's current source mod with great success on a couple of 1980's in the past, forget what the current transistors are and changes needed to the design since the original posting used Zetex transistors which are nla and a TX board which was outstanding.
-Lee
 
EchoWars current regulator is ALL the regulators,
MTF current regulator IS EchoWars schematic, it's merely a physical way of putting it together.

Glenn (EchoWars) had a little custom circuit board made up, which accommodates ecb type transistors, while the MTF regulator layout
uses the trick of the ebc transistor layout to lay it out on a simple 3x6 matrix perfboard fragment.

current_regulator.JPG

Hat tip to hoggwild89 for the drawing!!

Copy of current_regulator_mtf_1.jpg

it's small, those are 3mm LEDS.
 
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EchoWars current regulator is ALL the regulators,
MTF current regulator IS EchoWars schematic, it's merely a physical way of putting it together.

Glenn (EchoWars) had a little custom circuit board made up, which accommodates ecb type transistors, while the MTF regulator layout
uses the trick of the ebc transistor layout to lay it out on a simple 3x6 matrix perfboard fragment.

View attachment 930727

Hat tip to (name the ak'er) for the drawing!!

View attachment 930731

it's small, those are 3mm LEDS.

Excellent, great stuff thanks for the clarification, I'll get on it!!

There is a BOM in Mattsd thread for the parts, so that makes it easy, I'll use that....


The TxTurbo board is a drop in and works like a champ. On the other hand the original board can be rebuilt with the current source mod and will also work well and run cooler than the original design once you remote mount those four transistors. Figure on twenty hours in labor to rebuild it though if you work at the same pace I do---
I have used Mark's current source mod with great success on a couple of 1980's in the past, forget what the current transistors are and changes needed to the design since the original posting used Zetex transistors which are nla and a TX board which was outstanding.
-Lee

I'm going to rebuild it, the customer doesn't want to spent "that much money" but it will be "that much money anyway"!!
 
Just working through the AWR154 board, I have all the caps except the axial ones in stock, I have some of the transistors, so I have gone ahead with starting to rebuild and cleanIMG_4593.JPG .
I have some breadboard so I will cut them to size for the current source mod....
Put an order in with Mouser, and yes, orders over $100NZ have free shipping.....I Used the entire BOM so I can replace my stock I've already used...
This is where I got to today....She's pretty toasty!!
 
Not much to report, waiting on parts, I thought I had some ZTX transistors but I didn't so waiting for the Mouser order to turn up which will be here in 5 days.
I'm warming the customer up to the idea he needs me to go through the rest of it as well....
I actually ordered everything including relays to do the whole job...
 
Let me but in for a moment:
I finally finished the EW mod on this 1980. All hot Q''s are remote mounted.
This is a very good mod but it does take some time to fabricate up. Probably spent most of three hours making up the harnesses, drilling, tapping and double checking.
I used an epoxy to bond the harnesses to the PCB. I'd like a better way. I can't find those Molex solder/PCB, TO-220 sockets. Seems they are obsolete.

DSC04011.JPG

Back to your interesting thread.
 
You can get the molex connectors, just have to lob a little bit off the transistor legs on the ones I have here, I'm not at work for a few days, I'll get the part numbers and post.
I'm only going to remount the +/-80v Regs, I am going to use a different heat sink for the 30V....
I'm also going to see if I can fashion up some sort of connector for the board end, I actually have molex sockets that could do it, or maybe bolt a bracket on the board and use cable ties, not entirely sure yet...
I don't like the idea of the epoxy....
A dob of silicon would be okay at least you can peel it off, the epoxy will be hard to deal with once its set and you want to remove that cable for some reason.....

lot to think about.....I have time while I wait for my order to turn up in a few days...
 
well, one comment about remote mounting the transistors:
There are eyelets available from Mouser that can be installed in the board
at the transistor location to anchor the cables more securely and prevent any damage to the foils.
I use them when mounting a to-126 replacement to a to-92 in a mechanically vulnerable location, (like the sx-1250 psu)
and whenever a to-220 is mechanically vulnerable or has damaged foils.
mouser part number 534-23 Keystone Electronics Circuit Board Hardware - PCB EYELET 1/16 X.093
 
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