[solved] GW Instek GDS-820S oscilloscope - no boot - Page 1
Forum section: electronics / repair

author: shakalnokturn
author_rank: Super Contributor
timestamp: December 28, 2020, 02:34:28 pm
content: Cheap oscilloscope sold as "powers on, blank screen" soon after the seller got back to me to say "it won't power on, must be a PS problem".Once received opening the scope I found the line trigger connector disconnected from the PSU, standby PSU was working but main power would not respond to power soft key press.On primary side there's a 2 pin connector that can be used to force the main power on, the connector is same type as the line trig. one, I imagine the seller had last minute regrets on selling a scope that may be a too easy fix, went in to check to do whatever he could and went and connected the line trig connector in the wrong place...Found TL3842 (60between Vcc/GND pins), 2SC1815 (power enable to the 3842) and 5.1series resistor on Vcc open, fits well with the wrong connector scenario.After replacing these main power and soft key work, so I get a scope that powers on with a blank screen.Checking around with the thermal cam. doesn't show anything alarming, doesn't show there's much going on at all actually.On CPU board 3.3V power is good.The line trig. leads to a trigger selector daughter board on the lower PCB (F.E. and acquisition), expecting the miss-wiring may have caused havoc there I checked for burnt components and tried removing the full acquisition PCB in case it was holding the CPU bus low. No better...Next suspicion was a corrupt firmware so I started looking for that and came across these:https://wiki.leedshackspace.org.uk/wiki/Electronics/GDS-820SQuotehttps://www.gwinstek.com/en-global/products/detail/GDS-800Firmware:https://www.gwinstek.com/en-global/products/downloadSeriesDownNew/12124/1054I first tried Realterm on the serial port to see if it was responsive, Power On Reset does give an output from what looks like a bootloader.Next the Instek update software, which does complete the update sequence but the scope is still in the same state after the update.Probing at the HY29LV160BT flash during a POR shows bus activity for a few seconds then seems to freeze at one point, buses still active but probably stuck on a very short loop.Probing HY29LV160BT during firmware update shows no bus activity at all, so although the CPU responds to the software to initiate the update it doesn't write the received data to the flash.Broken bootloader or hardware fault?

author: shakalnokturn
author_rank: Super Contributor
timestamp: December 28, 2020, 07:33:49 pm
content: Would anyone have a working dump of the flash or a clue on how I may be able to extract the image from the Windows update software?

author: nctnico
author_rank: Super Contributor
timestamp: December 28, 2020, 08:08:17 pm
content: Have you tried the HELP command to see if there is anything useful to be done with the bootloader (for example: a flash check)?

author: shakalnokturn
author_rank: Super Contributor
timestamp: December 28, 2020, 08:58:18 pm
content: Hi,Yes, tried "HELP" uppercase, lowercase, tried throwing it some remote control commands all it ever returns is something along the lines of "unrecognised command".

author: shakalnokturn
author_rank: Super Contributor
timestamp: December 29, 2020, 02:56:04 am
content: I kept trying, I wasn't really understanding why the scope would return random looking characters in the middle of a sent command.After a while sending the "help" command one got through uninterrupted and gave me some basic return with a choice of "BOOT", "UPDATE" or "version" additional commands.I tried throwing it some simple U-Boot commands too, but it did not respond, looks like a very boiled-down version.Then I moved on to capture the scopes TXD output while attempting a firmware update which showed that the software was getting the sameas I was seeing with Realterm, no hope it would update that way..Code:Gboot >updateUpdate Firmware ...xQuitUpdate FailedFirmware not programmed!!Please Cycle Power Redo UpdateGboot >315¶Ã01045FŠS±5FFÃ0002°4600C08°8°00´7Unrecognized CMDGboot >±Æ1Ä010´7E0FF0ÂUnrecognized CMDGboot >Gboot >S10·D07¶87EÅQuitGboot >315F9Ä026E6E0±10°8E±77°D00Unrecognized CMDGboot >S1F°±20ÂD03·CDD°6FS35FÃ1000E29B0°8000324QuitGboot >Æ0°Aµ058855Ä07Ä50D87E¶Unrecognized CMDGboot >Ó1Æ0AD°49D509¹86ÅEUnrecognized CMDGboot >Gboot >S15D°³A46D5FQuitGboot >S3±E°3AA·AD°3ACÃD0Â0D0B6D7xQuitGboot >5F06Å070³B18Ä0BÁ6E5Unrecognized CMDGboot >Gboot >³1Ã6CC°502Ä5Unrecognized CMDGboot >Gboot >Ó3±652µ57Å1BUnrecognized CMDGboot >ŠS3E56FÆF8´±F9°07Â1AS35FÃ0²1´9°01Ã6E308Å9Unrecognized CMDGboot >±Æ±094³F90346µUnrecognized CMDGboot >Gboot >Ó30¸68D°814ÃCUnrecognized CMDGboot >Gboot >31¸797Ã90±00Unrecognized CMDGboot >ŠS3E4EÂ900°5CA·2F°04S35FÃ0·4·200A·00ÆFCD6Unrecognized CMDGboot >1Æ±FE·60ÄE08µ5Unrecognized CMDGboot >Gboot >Ó3³°67¶002Å2BŠS31µFC±1A17¶0²0´306621C°ASµF002´5C1E2´9³Æ±³·²´0803Unrecognized CMDGboot >F184ÄE0C¸Unrecognized CMDGboot >Gboot >Ó3³64EÃ7C0³8EUnrecognized CMDGboot >ŠS1C00±83´514°324´94S±5F12012C0180288211¹S5C²E1010²8±8ÅÓÆ°001881D´SF3´²8A´1750¹6792µSF0Å2174³5²3Å8Ä0E310200²3ŠF882122E±0Ã455Å6SC8°8Æ02Unrecognized CMDGboot >Æ28F0029Unrecognized CMDGboot >Gboot >Ó3°021°30°66ŠS315FC0201¶6Ã1°0Â8¶00AF74S5Ã20C0Å·0808CUnrecognized CMDGboot >1Æ²0¸14A°0663Unrecognized CMDGboot >Gboot >Ó3Ã¶48°4A0²01Unrecognized CMDGboot >ŠS3³644Ã0A1C0³±08°70S35F10²4¸4022¸60512±ÄS5C³38CAD°²Å24SÆ°±30D5081ÓF33Ã60Ã231010B¸2°SF0CDC24¸5³000±5F31°0204AŠFA80°134±0±0127°SC0¸7²17Unrecognized CMDGboot >F³0213Â6Unrecognized CMDGboot >Gboot >Ó3³430°031BAUnrecognized CMDGboot >ŠS3004±³40°006±30µ4FUnrecognized CMDGboot >35F2001Å67µ°0Á8C7ÃUnrecognized CMDGboot >S³54000Ã7007C0¸²4ÄCUnrecognized CMDGboot >Ó35°080D13´20°°E1EFUnrecognized CMDGboot >Ó3µ20²218¹1C0°2256AUnrecognized CMDGboot >S3µE485C°6CCµ454°56S35FC0µ850140³3015140xQuitGboot >F142µC29°D2E±04A¹Unrecognized CMDGboot >Gboot >Ó1±097Ã70³CDUnrecognized CMDGboot >ŠS3Ä08´0001732°11´19S35FÃ0¹0±29C1³0490025Unrecognized CMDGboot >1Æ´151°31¸0092Unrecognized CMDGboot >Gboot >Ó³0°1428060ÃAUnrecognized CMDGboot >Ó31Æ66´2E0Á0A2Æ02²CAŠS1µF14°F°CA10°4C°E8²8S5Ã400CC0²µ²°°³Æ´¹Â°C160¹ÓF06·4A¸°Unrecognized CMDGboot >µ0E952B4BŠS3±5FF10500·CE4CE6E6E31¹36Unrecognized CMDGboot >35C5°034²801°32FUnrecognized CMDGboot >Gboot >S1F±F24µF4E6QuitGboot >315FFÆF04¸D70Ã0C´13´48°027Unrecognized CMDGboot >S1F·30C°04C³108090S35FÃ0500A2120°±962052QuitGboot >Æ0µ9Á0B4000¶11´0007102Unrecognized CMDGboot >Ó1ÆCB4²23±628°00Ã3Unrecognized CMDGboot >Š310AAÃ290¸103²10°67ŠS±FF±50680B¸1Ä2C²54´1S5Ã5Æ24C040·°Ã³Æµ8¶27438Ã3FEE013³4Unrecognized CMDGboot >µ50CC´518Unrecognized CMDGboot >S3±4E642°2EÃ´8D·00ÁS³5FC017B5920µ2Æ8CF45xQuitGboot >Æ121E±542¸36C±A0061A1Unrecognized CMDGboot >Ó3µ80°072²038²84Á82ŠS1µF±0´4¶5µ141A°80´063F10´0Á607CC4Unrecognized CMDGboot >1C6¸127´C0B·6Unrecognized CMDGboot >Gboot >Ó1°861³801¸1Unrecognized CMDGboot >ŠS3±114±9C2F01±±C±81Unrecognized CMDGboot >35F7410°42¸°14¸24´S³5FC0A0°0±1B10ÃF86058S5C6·408E3´°ÂDUnrecognized CMDGboot >51°C2Á6F0°42Unrecognized CMDGboot >ŠS1B0°9E1¸842¸112B41Unrecognized CMDGboot >S±5³¸06´340FFFÆ22BUnrecognized CMDGboot >Gboot >S17°³4±560²AQuitGboot >315A7E²5DE°741C05·0±8811°4Unrecognized CMDGboot >S1F8´665·4B±420095ŠS35FÃ0²07680·4Á40·81²µS5Ã·0D82Â±0F5EQuitGboot >10´8²745°00F´07°F201Unrecognized CMDGboot >Ó3501°245Ã8A0²DE¸FFUnrecognized CMDGboot >S3µ5²Å15´1F4°8000A5S35FÃ0·2·7°1001·20°14xQuitGboot >F1843EB00±7C°5011´1²Unrecognized CMDGboot >Gboot >31µ213¸081AAUnrecognized CMDGboot >Gboot >Ó1¸051Ä08²27Unrecognized CMDGboot >ŠS3F34²03B¹40F412¶C2Unrecognized CMDGboot >S3566A2¸8C1³2F7µ1A¹I had spotted a unpopulated TTL serial header on the CPU board, having a prolific USB to serial TTL around I gave it a try that way...The scope updated and rebooted to a normal screenSo it looks like I may have a defective SP202 RS-232 driver.Surprisingly the line trigger is working normally.To be continued as two of the front BNC's have been mutilated with a wire cutter and need replacing...

author: shakalnokturn
author_rank: Super Contributor
timestamp: January 03, 2021, 03:41:00 am
content: Hopefully last update:Swapped the SP202 for a MAX232 that was in my pulled parts. Serial port now working, I did a new FW update to check.Swapped the mutilated BNC's for a pair in my pulled parts. Required sacrificing an extra nut to get them level with remaining original BNC.Epoxied broken rear feet back together and added a layer of cork for padding.Wanted to test the FreeView software over USB on a XP machine. USB connection was hazardous at the best, after it crashed the laptop and I lost use of the mouse on the main PC I decided something needed looking at.First fear was that unearthed use may have also killed the FT245BM in the scope.After one more disassembly and a few minutes poking with the DMM I found USB Vcc shorted to ground...That turned out to be a factory quality check overlook.Two pins of USB connector were bent. Well... You get what you pay for...

author: danymogh
author_rank: Regular Contributor
timestamp: January 11, 2021, 12:49:28 pm
content: Nice job on the GDS820!I have a GDS-1054B which firmware I corrupted by accident using SSH.now after trying to reflash the firmware to the NAND I still can't get it to boot. there are 3 or 4 pin headers on the CPU board. How do you recommend I proceed?