IWATSU DS-8710 Oscilloscope "auto cal error(3)" ,Seeking Help - Page 1
Forum section: electronics / repair

author: daisizhou
author_rank: Super Contributor
timestamp: September 05, 2025, 11:56:34 pm
content: A few days ago, I successfully replaced the LCD polarizing film of the DS-8710 oscilloscope, and the display has returned to normal.But when I perform auto calibration, the error code AUTO CAL ERROR(3) appears.[CH1\CH2 is in no-load state]I don't know where the problem is, if anyone knows please help me, thanks****I have not been able to find any IWATSU DS-8710 service manual or circuit diagrams. If anyone knows any information about this, please let me know. Thanks.***

author: daisizhou
author_rank: Super Contributor
timestamp: September 07, 2025, 08:37:44 am
content: Please see the test video below, I tested ERROR1 and ERROR3

author: daisizhou
author_rank: Super Contributor
timestamp: September 08, 2025, 11:16:21 am
content: Can someone help me find the service manual or schematic for the IWATSU DS-8710 digital storage oscilloscope?

author: daisizhou
author_rank: Super Contributor
timestamp: September 09, 2025, 12:58:19 am
content: Here is a picture of the interior.I don't know how to begin investigating this ERROR3 fault.There is no useful information at all.

author: daisizhou
author_rank: Super Contributor
timestamp: September 09, 2025, 11:33:37 am
content: On this board, I found 3 adjustable potentiometers.It seems to be adjusting the 15v voltage

author: daisizhou
author_rank: Super Contributor
timestamp: September 09, 2025, 10:41:06 pm
content: I used a digital multimeter to test the test points above, and the voltages were 5.0v, -4.99v, and 5.0v. The voltages on the three wires were 5.0v, 0v, and 21.98v.It seems that the 3 potentiometers are not related to these voltages.I don't know how to adjust them correctly.I am stuck in finding ERROR3.

author: TinLethax
author_rank: Regular Contributor
timestamp: September 10, 2025, 12:11:11 am
content: Did you try calibrationwithout attaching the probe to the probe compensation signal?

author: daisizhou
author_rank: Super Contributor
timestamp: September 10, 2025, 12:51:36 am
content: Quote from: TinLethax on September 10, 2025, 12:11:11 amAs shown in the video above, I connected two 100M oscilloscope probes to CH1 and CH2, left the inputs floating, and retested the auto cal, displaying ERROR1.In general, it is correct not to connect any probe to the BNC interface when performing auto cal test.But ERROR3 still exists

author: TinLethax
author_rank: Regular Contributor
timestamp: September 10, 2025, 08:48:43 am
content: And did you try without connecting the probes ?

author: daisizhou
author_rank: Super Contributor
timestamp: September 10, 2025, 08:59:36 am
content: Quote from: TinLethax on September 10, 2025, 08:48:43 amCH1/CH2 is not connected to any probe and displays Error3

author: TinLethax
author_rank: Regular Contributor
timestamp: September 10, 2025, 09:04:06 am
content: That's not good :'(You'll have to locate the calibration circuit. Usually it's DAC and possibly MUX connected from DAC to each analog input channel.Check if the voltage rails are OK and also check the DAC output. Also check if there's any noise in the voltage rail. I've heard that it can cause self cal to fail.

author: daisizhou
author_rank: Super Contributor
timestamp: September 10, 2025, 09:37:05 am
content: Quote from: TinLethax on September 10, 2025, 09:04:06 amDo you mean for me to carefully inspect the PCB circuit board below?(Can be zoomed in to view)I couldn't find any useful information related to DS-8710, the only one is the instruction manual

author: daisizhou
author_rank: Super Contributor
timestamp: September 10, 2025, 11:12:22 pm
content: I took pictures of DCPU BOARD and DAS BOARD(Can be zoomed in and viewed clearly)https://i.postimg.cc/zBqwYh6F/DAS-BOARD-1.jpghttps://i.postimg.cc/pr6Kj6Ts/DAS-BOARD-2.jpghttps://i.postimg.cc/J76NSGqj/DAS-BOARD-3.jpghttps://i.postimg.cc/m2PY4BXJ/DAS-BOARD-4.jpghttps://i.postimg.cc/XqJwpbVZ/DCPU-BOARD-1.jpghttps://i.postimg.cc/rF7SF37m/DCPU-BOARD-2.jpghttps://i.postimg.cc/NjTRybwx/DCPU-BOARD-3.jpghttps://i.postimg.cc/Bv0H2DSf/DCPU-BOARD-4.jpghttps://i.postimg.cc/SRJMmfrC/DCPU-BOARD-5.jpghttps://i.postimg.cc/PJ98Jv3c/DCPU-BOARD-6.jpghttps://i.postimg.cc/7PWzmjHV/DCPU-BOARD-7.jpghttps://i.postimg.cc/3J0v69WH/LCD-KEYBOARD.jpg

author: TinLethax
author_rank: Regular Contributor
timestamp: September 11, 2025, 12:21:11 am
content: There are DACs ic14IC1, 14IC2 and 14IC3on the back of the DAS board. The 14IC3 is probably used for the offset adjustment of each channel. And the 14IC1 and 14IC2 can potentially be used for the DC calibration on each channel.14IC3 :https://docs.rs-online.com/bf60/0900766b81229fe5.pdf14IC1 and 14IC2 :https://www.ersinelektronik.com/class/INNOVAEditor/assets/Datasheets/MB88351.pdf

author: daisizhou
author_rank: Super Contributor
timestamp: September 11, 2025, 01:36:27 am
content: Quote from: TinLethax on September 11, 2025, 12:21:11 amDo you mean to ask me to measure the resistance between the AO port and GND of each chip 14IC1, 14IC2, and 14IC3?Use the resistance or diode range of a digital multimeterWhen I press AUTO CAL, I can hear the sound of the three relays in channel 1 and channel 2 closing or releasing. After the sound, ERROR 3 appears on the screen.

author: TinLethax
author_rank: Regular Contributor
timestamp: September 11, 2025, 05:27:36 am
content: Check voltage on pin 10 and pin 11 of the 14IC3, Pin 8 and 9 of the 14IC1 and 14IC2.

author: daisizhou
author_rank: Super Contributor
timestamp: September 11, 2025, 07:39:23 am
content: Quote from: TinLethax on September 11, 2025, 05:27:36 amPlease see the picture, they are 4.97v and 3.50v respectively

author: daisizhou
author_rank: Super Contributor
timestamp: September 12, 2025, 12:01:39 am
content: Quote from: TinLethax on September 11, 2025, 12:21:11 amIt seems that 3.50v voltage is a bit low, but this is the actual measurement value.If there are other things you need to test, please let me know and I will do the measurements.I have measured the voltage value of the power supply, please refer to the following figure

author: daisizhou
author_rank: Super Contributor
timestamp: September 13, 2025, 02:46:24 am
content: Hi TinLethaxDo I need to purchase several new MB88346B and MB88351 chips to try replacing them?

author: TinLethax
author_rank: Regular Contributor
timestamp: September 13, 2025, 01:54:26 pm
content: Don't buy and replace them yet. please check all voltage regulator to see if the measurement make any sense (for example 7805 outputting 4.9 is fine, but something like 4.7 4.6 or 4.5 then you need to doubt that chip, just desolder it out and test it separately with dummy load).

author: squadchannel
author_rank: Frequent Contributor
timestamp: September 13, 2025, 02:39:49 pm
content: you should check the attenuator relay. try applying voltage to the coil and see if you get a good resistance.if you're concerned, you can remove relays and check. if looks fine to applying in circuit, you can apply voltage as is. is it a low-side driver, just connect it to GND.

author: daisizhou
author_rank: Super Contributor
timestamp: September 13, 2025, 10:27:07 pm
content: Quote from: squadchannel on September 13, 2025, 02:39:49 pmThanksWhen I run "AUTO CAL", I can hear the internal relay opening and closing sound.When I rotate the "VOLTS/DIV" knob in the user interface and see the range change in the lower left corner of the screen, I can also hear the sound of the relay disconnecting or closing.Finally, in the normal use interface, I used the signal generator to input the signal and tested the range accuracy test on CH1 or CH2 respectively. It seems to be normal.After the above test, do I still need to disassemble the relay for offline testing?(If my description is unclear, please let me know and I can shoot a test video.)

author: daisizhou
author_rank: Super Contributor
timestamp: September 13, 2025, 10:58:21 pm
content: Quote from: TinLethax on September 13, 2025, 01:54:26 pmI carefully checked the power supply and found that there were only 3 adjustable potentiometers, Marked 15VR1, 15VR2, and 15VR3 respectively,but the exact set voltage values ​​were not marked around them.The circuit seems to be a DC/DC power supply, not an LDO regulated power supply.In addition, two unknown components were found. They seemed very special, but I couldn't tell their exact models. They seemed to be unique to Japan.*The voltage value of -21.91v seems a bit special, and the other voltage values ​​seem to be normal values ​​of 4.99-5.0*In the power input section, there are power adapter input and battery input. The power adapter voltage is DC 12V and the battery input is 7.2-8.4v. I tested them separately, but the AUTO CAL test still reported an error.

author: squadchannel
author_rank: Frequent Contributor
timestamp: September 14, 2025, 01:41:46 am
content: check whether good contact is obtained. Tek TDS attenuators will fail SPC due to bad relay contacts.

author: daisizhou
author_rank: Super Contributor
timestamp: September 14, 2025, 03:52:19 am
content: Quote from: squadchannel on September 14, 2025, 01:41:46 amHow can I test these relays? (Can I only remove them from the PCB individually and test them one by one?)Is there a simple and efficient way to do this?CH1 or CH2 uses the 0.6mv 1khz signal square wave that comes with the oscilloscope, and it seems to be displayed normally

author: daisizhou
author_rank: Super Contributor
timestamp: September 16, 2025, 08:11:24 am
content: I'm still checking, does anyone have a better suggestion?I don't know how to test the relay

author: TinLethax
author_rank: Regular Contributor
timestamp: September 17, 2025, 12:32:58 am
content: You can try desoldering the relay from the board. Use power supply to energize the coil, and use something like multimeter to check the contact resistance.Alternatively and easier, You can turn the oscilloscope on then input a known signal to the analog channel, then use another oscilloscope to probe before and after relay signal path to see if you get any signal after the relay.

author: daisizhou
author_rank: Super Contributor
timestamp: September 17, 2025, 03:05:06 am
content: Quote from: TinLethax on September 17, 2025, 12:32:58 amPlease refer to the following image,I tested CH1/CH2I'm not sure if this is correcthttps://i.postimg.cc/rsD5fLB3/cable.pnghttps://i.postimg.cc/rs7xbPcm/CH1.pnghttps://i.postimg.cc/c1zRrrYS/CH1-TEST1.pnghttps://i.postimg.cc/tCVhPptV/CH1-TEST2.pnghttps://i.postimg.cc/52d8STnK/CH1-TEST3.pnghttps://i.postimg.cc/XYfdHLPj/CH1-TEST4.pnghttps://i.postimg.cc/XvnFTFMw/CH2-TEST1.pnghttps://i.postimg.cc/jjvNK5KB/CH2-TEST2.pnghttps://i.postimg.cc/KzzTY28j/CH2-TEST3.png

author: TinLethax
author_rank: Regular Contributor
timestamp: September 17, 2025, 05:17:35 am
content: Try changing the volt/div. The relay would switch to select different attenuation. Then use another oscilloscope to probe the signal after the relay.I recently fixed the DPO2014 with the issue unrelated to the calibration. But it has the EXT trigger offset problem that I'm yet to fix (Self Cal failed). This could happened to you as well.You can try capturing a 1kHz sine by setting the trigger level to 0V so that the Zero crossing point of Sine is at the center of the screen. Then try to also feed the same signal into the EXT trigger channel and see if the zero crossing point is still sitting in the middle of the screen. If there's any voltage offset present in the EXT trigger signal path. Zero crossing point wouldn't be in the middle of the screen (the waveform would slightly shifted to left or right depends on the offset polarity).

author: TinLethax
author_rank: Regular Contributor
timestamp: September 17, 2025, 05:23:10 am
content: Also I found the Service manual from the similar model. They also mentioned the CD107 trigger IC too.https://www.scribd.com/document/384931154/service-manual

author: daisizhou
author_rank: Super Contributor
timestamp: September 17, 2025, 07:47:29 am
content: Do you mean that I should turn on the oscilloscope, adjust the volt/div knob, and then use the resistance range of the digital multimeter to measure the resistance of each pin of the relay below?What chip do you mean by CD107? I didn't find any CD107 mark.

author: squadchannel
author_rank: Frequent Contributor
timestamp: September 17, 2025, 09:29:19 am
content: Tek TDS, even when you input a signal and vary the amplitude of scope, it displays perfectly fine, but SPC fails. I think the calibration signal used by SPC is passing through the frontend relay.I know absolutely nothing about this scope, but if the signal used for auto calibration is indeed passing through the frontend relay, I think the quickest way to rule it out as the cause would be to measure the relay's contact resistance.set the generator amplitude that fits within the display range of the scope's amplitude settings and input it to compare the generator's amplitude to scopes reading. if it doesn't match, it's likely a relay issue.However, a slight DC offset deviation might be causing the error. It might not be visible.it's better to remove the relay and check it, but it's a pretty tight design. removing it seems like it'll be a hassle.

author: TinLethax
author_rank: Regular Contributor
timestamp: September 17, 2025, 09:54:09 am
content: Quote from: daisizhou on September 10, 2025, 11:12:22 pmCD107BFP, the IC (11IC3) on the lower right corner of the second picture.

author: daisizhou
author_rank: Super Contributor
timestamp: September 17, 2025, 09:54:55 am
content: Yes, the relays are SMD packages, which makes disassembly difficult.I need to be accurate in my judgment, otherwise I will damage the relays that are performing well.I don't know how to test these relays.

author: daisizhou
author_rank: Super Contributor
timestamp: September 17, 2025, 10:02:26 am
content: CD107BFP appears to be a specialized IC that cannot be purchased in the electronic market

author: daisizhou
author_rank: Super Contributor
timestamp: September 18, 2025, 09:33:43 am
content: Hallo everyoneCan I turn on the power of the DS-8710, adjust the "VOLTS/DIV" setting, and then use the resistance range of a digital multimeter to measure the resistance of the six relay pins?It seems that my operation is quite dangerous. I am not sure whether it will fail, so I hope to get your confirmation.

author: daisizhou
author_rank: Super Contributor
timestamp: September 19, 2025, 12:12:14 pm
content: May I ask if anyone can find compatible models for ASLD5W-K relays?

author: daisizhou
author_rank: Super Contributor
timestamp: September 20, 2025, 06:15:54 am
content: I checked all 6 relays and found that the CH2 channel relay seems to be working in the same position as the CH1 relay, with different pin short circuits or disconnection states.So I tried to disassemble it, but unfortunately, this type of relay packaged in a patch is very difficult to disassemble. I removed the solder connecting it, but there are still some residues left there, which makes it impossible to completely detach from the PCB circuitSo I used an external power supply with a 4.5V DC voltage to try to drive this relay. Soon, I heard the sound of the relay working and tested it. I found that the working state had been restored to the same normal state as the CH1 relay at the same positionSo I reassembled the PCB and entered the SYSTEM for AUTO CAL testing, at which point a prompt appeared indicating that AUTO CAL had been completedI thought the problem had been resolved, but unfortunately, when I tested it again, the AUTO CAL encountered Error3 againI tried adjusting the attenuation X10 of channels 1 and 2, as well as the "VOLTS/DIV" setting, while keeping both channels at the same settingBut the result is still, I don't know how to check next