Text preview for : GOS 6030 Reverse Engineer Document V5.pdf part of GW Instek GOS-6030 GOS-6030 Reverse Engineered Service Information. Revision 5
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GW Instek GOS-6030 Oscilloscope
Schematics Only
Reverse Engineered from the PCB's
THIS IS NOT AN OFFICIAL DOCUMENT PLEASE USE WITH CAUTION
Bob Ford 2017 Rev 5
GW Instek GOS-6030 Reverse Engineered Service Manual
Introduction
A few years ago the opportunity came along to purchase a number of GW-Instek GOS-6000 series oscilloscopes, all with faults/damage. A deal was then agreed, and for better or worse I became the owner of 16 6XXX oscilloscopes of varying specifications. The collection was then stored in my shed for a number of months until time/weather/incentive all peaked. The first step, find a set of manuals. Therein lay the first problem, as it would seem that service information for all GW equipment is as rare as the proverbial RHS. Further investigation confirmed that the manufacturer only supplies service documentation to dealers, or selected service agents. Not good at all. After sending a few emails using the GW online enquiry service, with no reply, the full horror of the situation dawned upon me, the scopes would need fixing without reference to service documentation. Subsequent attempts to obtain spare parts also failed dismally. It seems that ALL repairs should be through authorised dealers, and long gone are the days where test equipment came with a full service manual from new, along with easy access to spares. To cut a long story short, after fixing a couple of the scopes, and sketching out a number of partial schematics as I traced each fault, I decided to combine all of the schematic portions into a proper circuit diagram for much of the entire scope. At present it focusses on the 6030, however the other models with higher bandwidth use essentially the same circuits, but with small changes in transistor, CRT, and various component value changes. At some point I hope to group all variations in this document. In the end this took about 3 months of spare time, on and off to complete whilst still looking into other faults. The end result comprises this document. The schematics are a mixture of sections drawn from scratch, and others edited by cut and paste in `Paint', from other oscilloscope schematics. Because the circuit diagrams have evolved over time, they do not `flow' in a logical way. They are what they are, a group of interconnected blocks, which can make them tricky to understand when deciding what the circuits are doing. The limited amount of on-line service information for GW products was used as a basis for the `cut and paste' stuff, as some circuitry from the GOS- 600, GOS-61XX and GOS-62XX series `scopes is similar in a lot of cases. There are also strong similarities to some Isotech and Tenma circuits, plus I feel sure other re-branded `scopes will show a common parentage. Should anyone find errors, or have additional scraps of circuits from this or other GW `scopes, please leave details on this forum. I must stress that this is still work in progress, is far from complete, and most likely contains errors. So please use with the above limitations in mind. In the end, I hope it is better than nothing!
Block Diagram
Applicable GOS-6030 PCB Assemblies
OS-10P04C-2 OS-10P01C OS-01P03G-4 OS-10P03G-1 OS-10P03F-1 OS-10P03G-5 OS-10P02D OS-10P03G-6 ? OS10P03G-03
CPU Board Input Amp Board CRT Board HV PSU Board HV PSU Board (Build 2) LV PSU Board X Drive Board Y Drive Board Front Panel Board Potentiometer Board
Description
The GOS-6030 oscilloscope is the base model from a small range with varying bandwidths, capabilities and features (6031, 6051 etc.), the third digit indicates the bandwidth in MHz, and the last digit the specification level. My guess is that most, if not all of the internal circuit boards are common across the range (which I will confirm as I investigate the scopes in more depth), with a few extra boards installed, or varying build levels on the common modules to extend the specifications. The 6030 has 9 separate PCB's, with a mixture of PTH and SM build styles, the SM being double sided, and the PTH single sided. The single sided boards, especially the `X' drive board, come with a vast array of `link' wires. These links made/make fault finding on the `X' board (to me) particularly difficult. Unfortunately the majority of faults that I encountered were on this board, and I did come to loath it's `patchwork quilt' design, as when tracing the circuit very few tracks go straight from one component to another. My guess is that the board is a result of integrating older designs from individual boards onto a single one. This may also be borne out by the odd range of component numbers on the board, R5XX, R8XX, R2XXX etc. The design changes means the 6XXX use momentary controls (digital), this being the main difference from the 6XX series, which used conventional mechanical switches.
Fault/Servicing Notes
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Be careful of sharp edges on the chassis. It will bite! With any brightness issues or dim/weak traces, first check the CRT board for dry joints Access to the X input circuits can be tricky. Desoldering the screening plate at the two rear corners, and then sliding the plate to the rear will give access to the components. Undo the 6 fixing screws through holes in the PCB will allow the complete panel to be removed by sliding backwards and tilting upwards, be careful though as the front of the panel will jam against the boss on the plastic foot The `X' I/P circuits are roughly the same as the GWInstek GOS6200 `scopes. Until I get around to mapping the I/P board schematic, it will do at a pinch for general signal flow Main problems seem to be with the PSU's. The HV unit seems to eat the HT diode D1012. I've used R3000 ones as a substitute. Dry joints around the HV transformer are another issue. The LV PSU has a bunch of regulators and transistors that are fixed to the chassis for heat sink purposes, however I have rebuilt a board with the heatsinks and regulators etc. fitted to the PCB. During use the heat sinks do not get overly hot, so maybe it's only really needed on the scopes with more boards/features where more current is drawn The mains switch is a very weak area, I have found 3 scopes, all in new physical condition with O/C switches. I have been unable to find an exact replacement, but there are many versions available that can be used with a small amount of PCB fettling. This is another of my gripes about these scopes. The mains switch is fitted to the LV PSU PCB, and makes removal of the board a bit of a faff. I'm looking at alternate ways to mount the switch in future, and remove it from the PCB completely The relays on the X I/P board are all A5W-K, 2 Pole 2 Pos. Pin1 is at the black line marking, and not the square indentation in the plastic case Most of the S/M component on the X I/P board lack identification markings. This makes it tricky to transfer to a schematic
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LV Power Supply Board Image
LV Power Supply Board Schematic
HV Power Supply Board Image
HV Power Supply Board Image (Type 2)
HV Power Supply Board Schematic
CRT Board Schematic
Potentiometer Board Schematic
X Board Image
X Board Schematics
X Board Schematics
X Board Schematics
Y Board Image
Y Board Schematic
X Pre Amp Board
CPU Board