Help on Gorf Powersupply.

Finch

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I know, I should just get a switching supply and the adapter, but I already got the repair kit from Bob Roberts and installed it, so I'd at least like to get it working while I'm at it.

I installed every single component of the repair kit. The previous owner had replaced at least one of the original big caps with two caps stuck side by side.

So anyways everything is installed and I turned it on and I only get 3.8v out of the 5v line. 12v and -5v are perfect and I can adjust them with the pots, but 5v remains at 3.8 and the pot does nothing.

There are some resistors and (i think) caps on one of the ICs. I've looked at various pics of GORF powersupplies and some have these caps and resistors, some don't. There is a cap and a resistor on the back, and 2 on the front, and one pin of the IC on the front is lifted where the resistor is attacked. from the looks of the back of the board this was not original.

So I'm wondering if anyone can tell what's going on from the pictures, or has a working midway PSU of the same model as used in gorf and can tell me the configuration of their IC, and maybe I can revert this back to factory specs.

NOTE: I tried removing all of these extra components and then got no 5v at all...although at that time I didn't know that one pin was lifted.
 

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anyone? I know someone out there has one of these running properly.

I'm not able to adjust the 5v at all, it stays at 3.8 all the time so I think something is borked and it's bypassing the pot. Although with my limited electronics knowledge I can't for the life of me figure out how it should be set up.
 
I don't believe that my Gorf power supply looks like yours. I think my IC chips do not have anything mounted over top of them. I can look again once I open the game up tonight. Teh schematic that I am looking at doesn't seem to address the extra stuff that you have going on with that chip

Is it possible that the pot is bad? Unlikely, but certainly possible I suppose.
 
pots not bad, I've checked it with the multimeter. I've searched a lot on google for pictures of Gorf PSU boards, and some have a resistor and cap on top of the IC like mine, some don't. I've tried running mine with all the extra stuff, and then without and it honestly doesn't make a difference. I get the same result with only 3.8v that I can't adjust. The 3055 transistor is only outputting 3.8v, so I wondered if maybe that was the problem (even thought it was recently replaced from the bob roberts kit). I asked him and he thought it might be shorted to the heatsink but it isn't.
 
Did it work before you installed the rebuild kit? What all semiconductors did you install with the kit? Usually I'd say to check the 3005, but if you just replaced it, it should be OK. What about the voltage regulator (3532J)? Did you replace that?

-Ian
 
I take back my earlier assessment....My gorf does have the stuff on top of the IC, although I have a round resistor (kind of looks like the Gorf robot) rather than what you have. I'd venture to say that yours is the same specs, just repaired at some point while mine is the old crusty original.

Let me know if you want me to look at anything specific, but my knowledge base is not very good...I'm not very technically inclined.

Steve
 
Did it work before you installed the rebuild kit? What all semiconductors did you install with the kit? Usually I'd say to check the 3005, but if you just replaced it, it should be OK. What about the voltage regulator (3532J)? Did you replace that?

-Ian

Interestingly enough, as I remember, the 5v line was fine, and adjustable, before the repair kit. -5v was way too high and not adjustable. Now I've got a lot unadjustable 5v and -5 is fine and adjustable. NO IDEA WHY.

As for the 3532, its not included in the repair kit. Bob said it's discontinued and not easy to find.
 
I take back my earlier assessment....My gorf does have the stuff on top of the IC, although I have a round resistor (kind of looks like the Gorf robot) rather than what you have. I'd venture to say that yours is the same specs, just repaired at some point while mine is the old crusty original.

Let me know if you want me to look at anything specific, but my knowledge base is not very good...I'm not very technically inclined.

Steve

If you could take pictures of the front of your board, specifically the IC with the stuff stuck on it, and if possible, the back of the board, as mine had stuff stuck back there too.

The round thing might be a ceramic disc capacitor. I've seen pictures of a few gorf PSUs with these instead of the round glass one I have.
 
Not the best photos ever....kind of tight and dark in that area of the basement. I hope they are able to help you out.

Steve
 

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Not the best photos ever....kind of tight and dark in that area of the basement. I hope they are able to help you out.

Steve

no, those are perfect. That pretty much looks like how mine was before I did any work on it. The components soldered to the 3532 IC are different types than mine, but it looks like it's the same stuff, just different brands. I guess the stuff on the back is standard, even though it's not mentioned anywhere in the schematic, or it was a common mod.

I see some of your power input lines got fried too, mine were soldered to the back of the board instead of the pin like yours but its the exact same wires. I hear that's common.

Thanks again, should help me get this sorted out.
 
best wishes...I just battled various issues on mine for the past 6 weeks. Fixing the Optos tomorrow and then we should be fully functional!
 
joeycuda & wysiwyg2: Thanks a ton for the pics, those are helpful

Riptor. I may want one of those at some point if I can't figure this out otherwise, I'll let you know.
 
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