8mm Forum: help with gs1200

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Posted by Kevin Hassall (Member # 2352) on May 23, 2014, 10:40 AM:

can anyone advise me on this when i switch the projector on and turn the sound up there is a humming noise and when i turn it up a bit more the noise nearly pops my ears

Posted by Steve Klare (Member # 12) on May 23, 2014, 11:14 AM:

The audio circuits need DC (constant voltage) to operate. The power coming out of the socket is AC (pulsating positive and negative, 50 times per second). There are power supply circuits in the machine to convert the AC to DC.

It sounds like your power supply circuits are allowing too much of these pulsations through instead of smoothing them out. If this is the problem it's most likely a filter capacitor or a rectifier has given up the ghost.

Posted by Kevin Hassall (Member # 2352) on May 23, 2014, 12:43 PM:

i wish i knew how to repair projectors but i dont looks like i cant use it now i dont know where there is anyone near me to repair it for me arghhh

Posted by Andrew Woodcock (Member # 3260) on May 23, 2014, 04:52 PM:

Does it have to be someone close by Kevin? I mean do you prefer to transport the projector yourself? If this is the case,I think I may have a contact in the Midlands. If you are interested PM me mate. If you are prepared to send it by courier Bill Parsons is the man.

Posted by Maurizio Di Cintio (Member # 144) on May 23, 2014, 04:54 PM:

Download the tech manual and give both the projector and the manual to an expert technician of electronics stuff. He should figure out how things work pretty soon and fix the problem.

Posted by Kevin Hassall (Member # 2352) on May 24, 2014, 02:57 AM:

i live in walsall and mr king from stoke use to repair them for me but he is retired now

Posted by Lee Mannering (Member # 728) on May 24, 2014, 03:23 AM:

From my own experience Bill Parsons does wonderful repairs and I would highly recommend him in the UK. [Cool]

Posted by Kevin Hassall (Member # 2352) on May 27, 2014, 05:12 AM:

hi andy i dont know if i did it right i pm you i ay very good at computers thanks buddy

Posted by Clive Carmock (Member # 347) on August 22, 2014, 05:46 PM:

Did you ever get this fixed?

I had a similar issue with my GS1200 Xenon machine. It started to very very badly crackle when turned on for about 15-20 seconds. I was told this was the STK443 amplifier IC failing, so I replaced it (a pain to get to on the Xenon machine). It ran fine for a while and then all I got was a loud HUM from the speakers. the replacement STK 443 had gone bad. I replaced it again and it seems to be fine now.

Could you maybe, get a recording of the sound, I'll try to identify if it was similar to mine.

Posted by Andrew Woodcock (Member # 3260) on August 22, 2014, 06:15 PM:

Nice post for Kevin that Colin, hopefully it will help with his problem which sounds very similar. I have offered Kevin the opportunity to send his machine to a vintage Audio Electronics expert in the North West, who for sure, will be able to diagnose the problem, and as long as the STK chip is still available, will be able to repair it for him.

Aside from the specialist (now often obsolete) IC Chipsets, I believe all other electronic components are pretty much readily available and this guy seems to work miracles, in all kinds of scenarios, to find now obsolete parts (Or improvise - see obsolete capacitor resolution on high end amps).

For anyone else within touching distance of the North West of England who may also be interested in such similar service for their machines, please refer to PR Audio Website, where if you look under the "other repairs" section and then "Beaulieu", you will see a detailed explanation and photo's of how this guy got my machine fully functional once again.

It took him less than 24hrs BTW to diagnose and repair!

Admittedly, probably quite a simple repair by this mans capabilities, but nevertheless, if you look through his past conquests, you cannot help but be impressed with his knowledge and capability when working on vintage electronic audio problems!

My machine was collected by me in identical cosmetic condition as when I dropped it off with him and now works perfectly fine, as when new.

I have just had a quick look and the Sanyo STK 443 IC as used by the GS1200 is still available on E Bay.

[ August 23, 2014, 03:24 AM: Message edited by: Andrew Woodcock ]

Posted by Maurice Leakey (Member # 916) on August 23, 2014, 04:51 AM:

One of my GS1200s developed an awful hum which didn't vary with the volume control.
I've just checked my service engineer's repair note which states:-
"Replaced capacitor on amplifier circuit P.C.B."
It's as quiet as a church mouse now!

Posted by Andrew Woodcock (Member # 3260) on August 23, 2014, 05:21 AM:

That is the problem Maurice in trying to diagnose these type of problems, in that it can inevitably be one of many different reasons to establish the root cause of what appears at first glance to be the same problem as what someone else reported.

Dry joints often feature in there on these older machines but often that is coupled with a failed component etc. In these instances, it is often impossible for us mere mortals to just second guess a solution in complex faults even with test equipment and it is always a relief to find an expert in this vintage audio field to someone like me. Chances are they can get within an inch of the problem on the board immediately just from past experience alone.

Vintage electronic audio repair is, I feel, fast becoming a very specialized business and I cherish the people around who can still come to our aid.

Bill as we have all said, is superb, but he is reluctant nowadays to take on "stressful" Jobs as he has to watch his health nowadays, therefore it is important to me to find local alternatives for the future in order to carry out these type of repairs long after Bill eventually calls it a day.

I much prefer also to transport my machines myself as based on past experience, projectors, no matter how well packed, do not travel well via courier services generally speaking.

Posted by Maurice Leakey (Member # 916) on August 23, 2014, 06:03 AM:

Good points, Andrew. I always take my projectors by car, it's a 138 mile run to my service engineer, it's very worthwhile as usually my load is around four to five of my darlings.

Posted by Kevin Hassall (Member # 2352) on August 24, 2014, 09:33 AM:

i havent had it fixed yet gonna get it took to bill parsons when i get the cash arghhhhh

Posted by Clive Carmock (Member # 347) on August 24, 2014, 07:13 PM:

The STK ICs for these machines are still available.

Note though that the Xenon machine uses an STK443 and the standard halogen GS1200 uses an STK439 both are available.

I bought a few of each from an electronics retailer from eBay. It was the STK443 I replaced on my Xenon machine. It's performing perfectly now.

It's a pain to get the main board out on the Xenon machine, but doable.

Posted by Andrew Woodcock (Member # 3260) on August 25, 2014, 03:28 AM:

Just for the record I would like to point out and make absolutely clear, having liaised recently with Bill, Elmo repairs do not cause Bill any stress as he knows these machines inside and out.

Therefore Bill hopes to continue to carry out repairs on all Elmo machines, (for which he has a very large inventory of spare parts) for many years to come, health permitting of course.

[ August 25, 2014, 04:32 PM: Message edited by: Andrew Woodcock ]

Posted by Andrew Woodcock (Member # 3260) on August 26, 2014, 03:21 PM:

Kevin I have read your PM update and I am pleased you are getting your main machine repaired very soon. I cannot reply to any of your PM messages you are sending me as I am on your ignore list as stated previously. Let us all know the outcome Kevin upon it's return.

Posted by Kevin Hassall (Member # 2352) on August 30, 2014, 09:31 AM:

hi andy soz about that was messing about on the computer and touched the ignor so sorry next mpnth my friend is gonna take because he is busy at the moment

Posted by Andrew Woodcock (Member # 3260) on August 31, 2014, 11:55 AM:

It will be spot on Kevin when you get it back from Bill, I can assure you of that. you are sending it to the very best place in the UK. Just make sure you pack it really well to overcome the way in which the couriers sometimes handle these delicate items if you do end up having to use a courier.

I am sure at times they think they are transporting beach balls!

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