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GW GOS-522 Oscilloscope Schematic/Circuit Diagram

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davenz

New Member
Hi everyone.

I have recently acquired the above scope and would dearly love to get a schematic/circuit diagram for it. The scope basically works but has some issues and a diagram would be hugely helpful. The main issue I have is with the trace brightness; it is almost non-existent and the intensity control does nothing to change that - in fact it does nothing at all. The pot is OK, my thoughts are either the tube is on the way out or the driver circuitry is dodgy. I have replaced some of the electros and this helped a lot; the rest seem to have 'burned in' OK.

Everything else works except for this intensity issue; I am thinking I could bump up the juice to the tube slightly in order to get some more life out of it as replacing the tube is not an option, unless someone has one for sale that is. Either way, I need s circuit diagram to help pinpoint what to do and where.

Thanks, Dave.
 

WME_bill

New Member
GOS-522 scope

No, I haven't got the manual. But I suspect this machine was made in the Far East and marketed under several different names. It might be sensible to post a picture, and see if it rings some bells. I suggest your fixed brilliance is due to faults with the bright up circuit. This traditionally uses a couple of high voltage transistors, which equally traditionally seem to fail under surge conditions. Trace that part of the circuit out, and test the output pair. The drive to the low potential end of the tube grid supply should vary about 50v with the intensity control. An easy fault to identify. Keep your meter and fingers away from the tube grid and cathode, as that will be a kilovolt away from earth. Look up the circuit of a few other scopes on the web. Not Tek or Philips or HP, as they are far too sophisticated. Try Leader, Hameg or similar. Bill m0wpn

QUOTE=davenz;812261]Hi everyone.

I have recently acquired the above scope and would dearly love to get a schematic/circuit diagram for it. The scope basically works but has some issues and a diagram would be hugely helpful. The main issue I have is with the trace brightness; it is almost non-existent and the intensity control does nothing to change that - in fact it does nothing at all. The pot is OK, my thoughts are either the tube is on the way out or the driver circuitry is dodgy. I have replaced some of the electros and this helped a lot; the rest seem to have 'burned in' OK.

Everything else works except for this intensity issue; I am thinking I could bump up the juice to the tube slightly in order to get some more life out of it as replacing the tube is not an option, unless someone has one for sale that is. Either way, I need s circuit diagram to help pinpoint what to do and where.

Thanks, Dave.[/QUOTE]
 

FreeThinker

New Member
Hi everyone.

I have recently acquired the above scope and would dearly love to get a schematic/circuit diagram for it. The scope basically works but has some issues and a diagram would be hugely helpful. The main issue I have is with the trace brightness; it is almost non-existent and the intensity control does nothing to change that - in fact it does nothing at all. The pot is OK, my thoughts are either the tube is on the way out or the driver circuitry is dodgy. I have replaced some of the electros and this helped a lot; the rest seem to have 'burned in' OK.

Everything else works except for this intensity issue; I am thinking I could bump up the juice to the tube slightly in order to get some more life out of it as replacing the tube is not an option, unless someone has one for sale that is. Either way, I need s circuit diagram to help pinpoint what to do and where.

Thanks, Dave.
Hi Dave
Did you ever sort out your scope?I have an Isotech ISR650 that I've been looking for a service manual, all I have found so far is this https://www.eserviceinfo.com and search for isotech which is the 20mhz ver of the same scope(Ithink).However if you look at the legend it says GW GOS-522.Isotech is the badge RS flys under and GW must be the OEM.I'm haveing similar problems to you in that my trace is quite dim at fast sweep rates and the Intensity control is fully clockwise, however the trace is very bright when A Int B is selected suggesting to me that it is abias problem.As I know less than nothing about analouge circuits i'm struggleing so any help or pointers would be welcome.Anyhow hope the link is of some use to you
 
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FreeThinker

New Member
Hi Dave
Did you ever sort out your scope?I have an Isotech ISR650 that I've been looking for a service manual, all I have found so far is this Service Manual free download,schematics,datasheets,eeprom bins,pcb,repair info for test equipment and electronics and search for isotech which is the 20mhz ver of the same scope(Ithink).However if you look at the legend it says GW GOS-522.Isotech is the badge RS flys under and GW must be the OEM.I'm haveing similar problems to you in that my trace is quite dim at fast sweep rates and the Intensity control is fully clockwise, however the trace is very bright when A Int B is selected suggesting to me that it is abias problem.As I know less than nothing about analouge circuits i'm struggleing so any help or pointers would be welcome.Anyhow hope the link is of some use to you

Fixed link (Sorry :( )
 
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