EII Power supply schematic question

[Futureman]

Hello all,

I'm fixing up a mates EII.
It was working untill he accidentally shorted out a part of the PS and killed it.

My present issue is that R106 is fried and open circuit.

I can't exactly see the value of R106 as it's damaged.. it seems to be

White Black Gold Gold -> 9 ohms (5%)

It could be Grey black gold gold -> 8 ohms (5%)

Unfortunately, the schematics i have (taken offline) don't have R106 on the schematics..  It's on the schematics, but it's value is not marked as the scan seems cut off.

Any one out there have an original hard copy of the service manual? More importantly the power supply?
(R106 is located in the top right corner, joining R105 and C104)

If you do, can you please tell me the value or R106? (It looks like a wire wound resistor.. can't tell exactly)

Cheers
Mike

[sfbaytech]

Mike,

Checking a working supply it is 1 ohm (brown, black, gold, gold) 5%. I would say flameproof 1/8w(so not wire-wound as this feeds the switching power transistor). I think you are going to find that Q103 (2n6545) next to it is shorted also.

Chris

[Futureman]

Cheers for that! You are a legend!

I've already replaced the Q103.

Just waiting for the resistor to arrive.

Kind regards
Mike

[synthnerd]

Hi all,
I got an EII+ in for repair last week, and the PSU is blown in the usual way. Q103 is shorted, R106 is open. R114 is open, C111 shows a permanent low resistance both ways, R107 has burnt out, the other remaining components around the chopper transistor seem OK, but my experiences of weird switchers would lead me to replace them anyway, just in case. My question is, is this going to be enough to get this PSU working again? or is there anything else I should watch for to prevent another meltdown on switch on. By the way the fuses were not blown, and the only discoloration on the low voltage power connector was on the two green 0V returns, and not the yellow wires that have been mentioned on this forum.
If the replacement parts mentioned would make it work again, then I would consider re-capping the entire power supply, and that leads to another question, for about the same kind of money I could get and fit a brand new Condor GPC-130C power supply, which is newer, more efficient, probably a better design, and as I need to replace the crimp connectors in the low voltage output connector anyway, rewiring the output connector in some form or other is going to be necessary anyway.
How have everyone managed with repairing the original supplies, and was it worth it?

John.

www.retroactivesynth.com

[synthnerd]

Hi all,
Having received no further replies or help from anywhere, I just decided to go ahead and replace everything that was obviously faulty, check everything else that wasn't and go for it. What was the worst that could happen? Another dead Q103 and some more burnt resistors. Finding a compatible off the shelf modern supply that satisfied all the criteria seems impossible even at any price.
It all worked, I switched it on with the lid up to watch for any signs of smoke or a flash, none occurred and the synth started flashing it's drive lights looking for a disk. Putting the lid down, watching the display and putting a disk in confirmed a working instrument. Half an hours playing confirmed it mostly works, and touching all the hot components half a minute after switch off showed nothing was too hot to touch.
A good result.

John

www.retroactivesynth.com