Blast from the past a Goldscan II

[Ferric Toes]

thx Eric. but his burnt tants on TX board while you shared RX ones.

Yes, but he also asked what was in the black box which is associated with the Rx board. There appear to be problems on the Rx board hence the circuits to show what is in the box. I would guess that the burnt tants were due to the supply voltage being reversed at some point in time. Perhaps the battery was changed and connected wrongly, if only briefly, at some point in the last 38 years. That is the common cause of tants failing. NiCad batteries do age and need replacement, but tantalum caps last indefinitely unless subjected to reverse voltage. That is my experience anyway.

[Paul Harris]

Here are two schematics of the GS2 Rx board. The earlier 1982 version in which the points that go to the potted module are circled in red. The second schematic drawn a couple of years later is more complete and I have highlighted the potted module within the dashed red lines.

[ATTACH]53870[/ATTACH] [ATTACH]53871[/ATTACH]

Eric

Thank you so much Eric, there is a wealth of information in those diagrams. The Tantalum's I'll be able to figure out their orientation no problem. Speaking to the father the other day and he says he had the GS2 working again, he says with very impressive depth. He's asked me to pass his phone number on to you so later I'll private message you his number if that is alright with yourself? Thanks again Eric.

[Ferric Toes]

Hi Paul,
Yes that would be good to be in touch again. I'll see if I can locate the Tx board diagram to see where those tantalum caps are. I'm sure that they are associated with the +5V and -5V regulators.

Eric.

[Ferric Toes]

Hi Paul, Found the Tx board info and located the two tantalum capacitors that failed. They were not where I thought they were in my previous post. Attached is a circuit diagram and board layout with the caps ringed in red. Both are across the -12V supply rail, so would blow quickly on a reverse voltage. Check the choke L1 to make sure it is not open circuit. If it was, there would be no +5V supply. I noticed that the board layout has a few things slightly different to yours, and a few extra components. This is because yours is an early one. It is basically the same though.



Eric.

[Paul Harris]

Hi Paul, Found the Tx board info and located the two tantalum capacitors that failed. They were not where I thought they were in my previous post. Attached is a circuit diagram and board layout with the caps ringed in red. Both are across the -12V supply rail, so would blow quickly on a reverse voltage. Check the choke L1 to make sure it is not open circuit. If it was, there would be no +5V supply. I noticed that the board layout has a few things slightly different to yours, and a few extra components. This is because yours is an early one. It is basically the same though.

[ATTACH]53878[/ATTACH] [ATTACH]53879[/ATTACH]

Eric.

Hi Eric, I've sent Bill's phone number to you by private message. I have noted the circled caps in question and the caps are now on order, hopefully that is the only damage done, I'll check L1 as you suggest shouldn't be much ado if there are other problems with those detailed diagrams. Thank you.

[TufaN]

hi is there pcb photos or lay file for GS2.

[Ferric Toes]

hi is there pcb photos or lay file for GS2.

I don't have any. Layouts were hand done in the 1980's with black adhesive pads and tape of various widths. Probably thrown away, years ago. The only way now is for someone to take a photo of the track side of the board and work from there. I don't have any boards to do this either.

Eric.

[profesor]

I don't have any. Layouts were hand done in the 1980's with black adhesive pads and tape of various widths. Probably thrown away, years ago. The only way now is for someone to take a photo of the track side of the board and work from there. I don't have any boards to do this either.

Eric.

You are so generous Eric. Thanks.

[TufaN]

engineer eric all your devices are great. I think the goldscan2 is a beautiful device. Maybe there will be those who take photos from our friends and share them. Thanks for your attention and for your reply.

[profesor]

paul harris goldscan 2 can you take pictures of pcb cards.
lower faces

[TufaN]

paul harris goldscan 2 can you take pictures of pcb cards.
lower faces. Please

[profesor]

goldscan 2 different photographs with open scheme.
+ 5V inverter, LM709 supply resistors are different.

[Paul Harris]

Hi All, well finally I replaced the caps on the GS II yesterday and everything is working much better I'm told. Thank you Eric for the diagrams made things much easier.

Tufan I have high res photos of the underside of each board, however, I don't really want to post them out of respect for Eric. If Eric were to give his blessing I'd be happy to share them.

[skorpio]

I don't have any. Layouts were hand done in the 1980's with black adhesive pads and tape of various widths. Probably thrown away, years ago. The only way now is for someone to take a photo of the track side of the board and work from there. I don't have any boards to do this either.

Eric.

add photos please

[Ferric Toes]

Hi All, well finally I replaced the caps on the GS II yesterday and everything is working much better I'm told. Thank you Eric for the diagrams made things much easier.

Tufan I have high res photos of the underside of each board, however, I don't really want to post them out of respect for Eric. If Eric were to give his blessing I'd be happy to share them.

Yes, that is fine by me, The only problem is the black potted box. I have shown what part of the circuit is in it, and that will have to be added on the board layout. This should be no problem with computer layout programs as there would be plenty of space available on a similar size board. One thought; better OK it with Bill too, as it is his detector. Bill's input as an enthusiastic user was very valuable in the Goldscan range of detectors.

Eric.