8mm Forum: GS1200 Take Up Spool Problem

This is topic GS1200 Take Up Spool Problem in forum 8mm Forum at 8mm Forum.

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Posted by Simon McConway (Member # 219) on August 04, 2008, 04:36 AM:

Well, it's not really a big problem, but sometimes the take up spool doesn't move. I simply stop the machine and restart, which gets the spool turning again correctly. Any advice? It doesn't always happen; it's intermittent.

Posted by Ugo Grassi (Member # 139) on August 04, 2008, 01:09 PM:

Typical problem: the defect comes from a relay on the main board. The contacts are oxized and the supply doesn't arrive to the arm motor. Stupid problem but to fix it is hard. You have to disassemble the main board and to clean the contacts in the relay. Other way is to change the whole relay.

Posted by Paul Adsett (Member # 25) on August 04, 2008, 02:23 PM:

I had exactly the same problem Simon, and had to cahnge out the relay as Ugo has stated. My take up was running intermittently, just like yours, and I would have to restart the projector sometimes to get it to 'Kick in'. Until the day I was projecting a 1200ft reel and noticed 600ft on the floor half way thru the film!
Changing the relay is not easy. I mangaged to do it - the worst part is getting the old relay out, it has about 11 pins on it and the relay has to be gently pried up from the board as you melt each of the solder joints - a real bear, I almost ruined the printed circuit board doing this. Once out though, soldering the new one in is a peace of cake.

Posted by Paul Adsett (Member # 25) on August 04, 2008, 02:25 PM:

I had exactly the same problem Simon, and had to change out the relay as Ugo has stated. My take up was running intermittently, just like yours, and I would have to restart the projector sometimes to get it to 'Kick in'. Until the day I was projecting a 1200ft reel and noticed 600ft on the floor half way thru the film!
Changing the relay is not easy. I mangaged to do it - the worst part is getting the old relay out, it has about 11 pins on it and the relay has to be gently pried up from the board as you melt each of the solder joints - a real bear, I almost ruined the printed circuit board doing this. Once out though, soldering the new one in is a piece of cake.

Posted by Kevin Faulkner (Member # 6) on August 04, 2008, 06:00 PM:

I had the same problem on my Xenon. I removed the relays using a solder pump and then lifted the relays off the board. I gave the contacts a clean and resoldered the relays back into the machine. It has now been running with no problems for several months.

This can be done without having to remove anything at all. The relays can be unsoldered from under the main circuit board but do use a solder pump to remove the solder then the relays will just lift out. Any other method will damage the board.

Kev.

Posted by Maurice Leakey (Member # 916) on August 05, 2008, 02:19 AM:

Kev

What is a solder pump?

Posted by Keith Ashfield (Member # 741) on August 05, 2008, 04:01 AM:

Maurice, please find below a picture of a "solder pump". It removes the solder residue and frees the pins to aid removal of components.

Posted by Maurice Leakey (Member # 916) on August 05, 2008, 05:48 AM:

Keith

Many thanks. Never heard of one! I see that it is actually called a de-solder pump.

I assume it acts like a hypodermic syringe in reverse, i.e. it sucks up surplus solder.

Posted by Martin Jones (Member # 1163) on August 05, 2008, 06:09 AM:

Just a word of caution based on many years (I won't admit to how many!) as a Tv Engineer. De-solder pumps are fine on medium to heavy solder joints, but are not recommened on faily light pc boards, as they tend to lift the circuit copper from the board (did you find this, Kev?). On printed circuits always use "de-solder braid" (Maplin).
This is like a compacted screening braid from, say, TV aerial cable, impregnated with a cleaning flux. It's placed on the joint, which is heated through it. The solder melts and the braid acts as a wick and soaks it up (like magic) leaving the joint free of solder. The size you use depends on the density of the printed wiring so that you dont clean joints you dont require to clean.

Martin

Posted by Keith Ashfield (Member # 741) on August 05, 2008, 06:46 AM:

Maurice, you am correct. It am de solder pump! It reminds me of the old joke about famous sayings -

"We will fight them on the beaches" - Sir Winston Churchill
"Once more into the breach dear friends" - Henry V
"Defeat is fine" - Nelson Mandela's chiropodist!
[Big Grin]

No offence intended in any language or nationality. [Smile]

Posted by Graham Sinden (Member # 431) on August 05, 2008, 07:21 AM:

Martin,

I have used desoldering pumps for years (solder suckers as we call them), and they are fine on small and fine solder joints providing you know how to use them. Generally speaking good desoldering is all about heat conduction. If when using a solder sucker it is not desoldering the small bit of solder left or its not melting, try adding a blob of more solder and then you will find it all sucks up easily. It may sound crazy but often it is better to add more solder and get more heat into the joint and you will be more successful desoldering. Not masses but just a small blob and allow a few seconds for the iron to melt all the solder. Also make sure the plastic tip of the solder sucker is flat and not melted.

If the circuit boards are made correctly they should not lift the pads if you do the whole operation quickly and efficiently.

Graham S [Smile]

Posted by Martin Jones (Member # 1163) on August 05, 2008, 01:37 PM:

Yes, Graham, solder suckers are fine if you are experienced in using them. The word is "experienced". And "experienced" applies to both the use of solder suckers and to repair work on pc boards generally. I used them for many years after PC boards came in (my TV and Radio repair experience goes back over 50 years to when everything was hard wired ) and well made modern (usually glass fibre) boards are much tougher than the older (Paxolin based) boards. I changed to braid some 20 years ago because those older boards tended to shed their copper. And in this Forum we are mainly talking about boards in equipment that is 20 years plus(!) old. With these braid is much safer. My advice was aimed at the "inexperienced"; no doubt both you and I have seen the results of repair work that went wrong! Far be it for me to teach my grandmother to suck eggs!

Martin

Posted by Paul Adsett (Member # 25) on August 05, 2008, 03:32 PM:

I used a 'solder sucker' when I replaced my GS1200 relay, but still found that the desoldering of the old relay was very difficult. I think, as Martin points out, that the problem is the hardening up of a 25 year old solder joint. Its just very problematic trying to get the old solder to melt and totally suck away from the holes in the board. And the fact that the holes are very close together does not help. So I take my hat off to Kevin and others who regularly take on electronic repairs of the GS1200.

Posted by Steve Klare (Member # 12) on August 05, 2008, 03:44 PM:

My problem with this stuff is I work in a building with very highly qualified solderers (solderists??), so I don't get a huge amount of practice. They (wisely) don't like the Engineers messing around with the saleable hardware.

I swear if I needed something like this done, I'd bring it to work and wind up owing someone a favor!

I'll go up to maybe a four pin device, beyond that it's off to the rework department.

Posted by Paul Adsett (Member # 25) on August 05, 2008, 04:10 PM:

I agree Steve. I spent 30 years working for Northrop Grumman, and they have fantastic technicians who really know how to solder (and de-solder)electronics, and they did a lot of 'bootleg' work for me on my projectors. There was one guy there who was incredible at soldering up wiring harnesses, with a myriad of wires. It was'nt until his retirement dinner that I learned the guy was color blind! [Eek!]

Posted by Graham Sinden (Member # 431) on August 05, 2008, 04:23 PM:

Sorry Martin, I didnt take into account that the GS1200 PCB is more than 20 years old (and the solder on it). The PCB's that I use are all modern double sided with plated through holes, and surface mount types. Certaintly the latest ones we use can take quite a lot of soldering and desoldering before you get any damage like tracks/pads lifting. You are right to be careful with something of this age. A bit of time and patientice is important particularly when there are no replacements available.

Graham S

Posted by Kevin Faulkner (Member # 6) on August 05, 2008, 06:03 PM:

All the GS's I have worked on will be of similar age and I have still been able to remove those relays without any problems. The solder pads are fairly substantial and the holes are larger than the pins of the relay.
I use a small soldering iron and make sure the solder is flowing well before using the de-solder pump to remove the well molten solder.
To date I have not had an instance where the track has lifted. One other thing I do to each pin is to use the soldering iron tip to lift and straighten the bent over pin before de-soldering.

The covers unclip off the relays quite easily and its then just a case of cleaning the contacts.
I use a small piece of thin card which I have drenched with switch cleaner and work this between the contacts. The card being rough helps to clean the contacts and I use a cleaner on the card which also has a lubricant.

If you lay the machine face down so you can get to the underneath of the board you will find you can get to all the contacts without having to remove the circuit board.
Next time I do another machine I will take some pics.

BTW I have never been able to get on with that solder wick stuff and found that I had to use a meatier soldering iron as the wick tends to take the heat away from the joint. The less heat the better which is why I prefer the pump. Just my opinion though!

Kev.

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