Simpson 260-6xlp Schematics - Page 1
Forum section: electronics / beginners

author: AardvarkM31
author_rank: Contributor
timestamp: November 24, 2021, 05:16:06 am
content: Hello,Because of reputedly being able to buy a oscilloscope for $25, I bought an HP for a bit more. Then came the Wavetek Function generator and just received a Simpson 260-6xlp. The meter does not show meter movement on the scales R1-R1K. R10K seems to work. I watched a video on YT which showed a possible spot for a resistor failure. On the video it was R19 which branches off of the 10K position after the potentiometer which shows a schematic for 260 3 - 6. The schematics I've gotten off of simpson260.com don't match the R19 value or the the other 6xlpm,different versions of the 6xxlp or any other of the 6 series in location, value and purpose.Plan on tearing it down but I don't know or where to look for it.Any assistance for the proper schematic or insight is appreciatedThanks

author: Stray Electron
author_rank: Super Contributor
timestamp: November 24, 2021, 01:39:03 pm
content: I would start by cleaning the selector switches and trim pots with DeOxit or something like that. I'm very surprised to hear that the manuals posted on Simpson260.com aren't correct!Not sure what you mean by "or the the other 6xlpm". Do you have more than one?I have a pile of Simpson 260 parts units. I'll look and see if I have any 6xlpms but I don't think that I do. Most of my 260s are early series.You might look-up the schematic for a Simpson 261. It might be closer to what you have.

author: AardvarkM31
author_rank: Contributor
timestamp: November 24, 2021, 02:09:00 pm
content: Hello Stray Electron,I was wrong, there are 2 versions of the manual, not the schematics. It is highly probable that one of the schematics is correct. I don't know which though. Can you tell me which of the Deoxit products you use, there seem to be many? I have the 260-6xlp and of course I don't know the difference between it and the 6xlpm. My first professional meter was a 260 ages/eons ago.Thank you for the hint on the 261, will take a gander.In case my humour didn't come across, was joking about the $25 oscilloscope!!Thanks you

author: AardvarkM31
author_rank: Contributor
timestamp: November 24, 2021, 02:15:02 pm
content: Howdy again,I am thinking that the problem is possibly the R3 resistor as the R10K is the only range that works. Would that be the correct value for it on my meter? Must be a bear to source the exact value. May I ask what wattage should be used.Again thanks

author: BILLPOD
author_rank: Frequent Contributor
timestamp: November 24, 2021, 02:53:25 pm
content: Good Morning AardvarkM31,The 10K Ohm setting uses the 9 volt battery, the others use the 1.5 volt D-cell. I found this out the hard way while repairingmy 260 after probing mains voltage using the Ohms setting.

author: AardvarkM31
author_rank: Contributor
timestamp: November 24, 2021, 03:05:07 pm
content: Good Morning to you! Just received the meter yesterday and put in a good D cell. Didn't inadvertently misuse it YET, that I know of. In your opinion I should just check out the D cell again for proper voltage?Thanx

author: BILLPOD
author_rank: Frequent Contributor
timestamp: November 24, 2021, 05:59:03 pm
content: I would look at the R1 and R100 parts of the circuitry.By the way, my 260 is the 6M series. Good luck and letus know what you find.

author: Gregg
author_rank: Super Contributor
timestamp: November 24, 2021, 09:34:41 pm
content: Here is a Simpson 260-7 schematic if it helps

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: November 24, 2021, 10:32:34 pm
content: You could check the volts on the probes. As you said, should be 1.5 V on 2 lower ohm scales. May be a bad connection?Buy the way, I think I have purchased three scopes each for under $25. One is a Tek 475. Still have it. Of course they needed repair.

author: WattsThat
author_rank: Frequent Contributor
timestamp: November 24, 2021, 10:53:08 pm
content: DeOxit: I’ve used the Gold, D5 spray and D100 versions. I find the D100 to be the best general purpose choice that actually does what it claims. It also does a good job on alkaline battery leakage on pc boards after you’ve cleaned up the worst of it with white vinegar.

author: AardvarkM31
author_rank: Contributor
timestamp: November 25, 2021, 12:03:44 am
content: Hello again,I have found a schematic for the 6XLP and the 6XLPM. Having difficulty deciphering it though. On this print I am looking at R25 which is a 8.2K. Need to locate it on the board also......Will keep and eye out as Thanksgiving will put a halt in my diet and electronic adventures.A quick also --- Where is a good online shop for electronic parts, 3AG fast acting 1 Amp fuses, 1% Tolerance resistors and good caps?Thanks

author: AardvarkM31
author_rank: Contributor
timestamp: November 25, 2021, 12:05:51 am
content: Hello Greg,It sure can't hurt. thanks for your time and assistance.

author: AardvarkM31
author_rank: Contributor
timestamp: November 25, 2021, 12:10:04 am
content: Hello Sir,What a great idea! First thing on my list. As an aside, I can't fix the meter, I am so out of my depth on scope repair. I wound up actually with s digital scope with CRT. HP with 100 MHz, still will eventually get a small Tectronix or something.Tanx

author: AardvarkM31
author_rank: Contributor
timestamp: November 25, 2021, 12:13:58 am
content: I have used the vinegar in the past. Today I went over the contacts with some isopropyl alcohol. It cleaned them up well, did not fix the problem although. The Deoxits seem quite expensive and I've read that CRC is a good cleaner without lubricant and the Deoxit was a good lubricant and cleaner. Thanks for your experienced recommendations!

author: AardvarkM31
author_rank: Contributor
timestamp: November 25, 2021, 02:31:58 am
content: Checked the probes on voltage on every resistance scale except RX10K and it looked like capacitors were charging up in that it started at about 350 mV and continued up to 816 mV, where it stopped increasing. Does that mean I am getting the 1.5 VDC?

author: Gregg
author_rank: Super Contributor
timestamp: November 25, 2021, 03:21:57 am
content: Aardvark,It looks like you could use a reasonably reliable digital multimeter to help troubleshoot your collection of test equipment. A DMM across the leads of your Simpson set to the lower ohms scales should show close to the 1.5V battery voltage.There should be a number of deals on budget friendly DMMs for black Friday. For instance on Amazon there is a limited time deal for a Uni-T 161B for $56.79 plus another 7% off coupon that expires in about 4 hourshttps://www.amazon.com/UNI-T-Multimeter-Resistance-Capacitance-Transistors/dp/B08PNS4G8QWith free shipping and not having to wait for the slow boat from China, this may be a good deal.I’m not saying you should spring for this immediately but might want to do some research on this forum. Amazon also has some higher spec Uni-T meters on the same deal, but not as good of a discount. If you miss this deal, there will be more if you hunt for them.

author: AardvarkM31
author_rank: Contributor
timestamp: November 25, 2021, 04:12:43 am
content: Thanks Greg, but this DMM is an Amprobe AM-530 which is as I recall a pretty good True RMS Chinese meter. Let me double check it in case?As it would have it, double checking the Amprobe, it seemed to work well except for capacitance...... A Radio Shack DMM showed the same voltage increase pattern as the Amprobe but it was also correct on the capacitance readings, by 20 nF on several .047 uF caps of different types. Weird !!!!!

author: AardvarkM31
author_rank: Contributor
timestamp: November 25, 2021, 04:46:43 am
content: Hello BILL POD,On the schematic I have of the 6XLP and the 6XLPM the R1 appears to be a 100K potentiometer across the meter and unless I am mistaken, I can't find an R100 resistor.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: November 25, 2021, 12:39:15 pm
content: On my 260 the volts on the probes at low resistance scales is 1.500 Volts. High resistance scale is 9 V.You need 1.5 volts on the probe to make the resistance measurement work. You are not getting the right volts according to your measurements.You should not be able to "see" any delay in the volts getting to the probes. Not with another multimeter.Note: There are no capacitors to charge up in the resistance measurements. There is only One Capacitor, Not involved in DC or Ohm measurements.Tracing the path from the battery to the probes should find the culprit.Check the 1.5 V battery out of the unit then the battery connections then the resistors in circuit.Wires connected to the spring battery terminals are frequently a problem.Hopefully it is not a switch.If the meter itself works at high resistance scale, it and it's adjusting pot are OKWally

author: AardvarkM31
author_rank: Contributor
timestamp: November 25, 2021, 03:07:03 pm
content: Happy Thanksgiving,Sounds like a plan. Understand the concept and will try to get some work on it before the family arrives.Thank you!

author: AardvarkM31
author_rank: Contributor
timestamp: November 26, 2021, 04:02:21 pm
content: Thank you,After cleaning the switches and tracing the 1.5 battery paths, it came down to a corroded blob of solder on the negative battery connector......Solderwicked it back to the surface (luckily there was still most of the original contact). Now have positive continuous contact and all functioning resistance ranges.You helped me get my mind right.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: November 26, 2021, 05:23:00 pm
content: A TA-DA moment. Now you have a state of the art (circa 1970) multimeter.Fortunately many repairs are very simple things that are not necessarily easy to find.A logical approach frequently is the best one. Not always, sadly.I did PM you also.

author: AardvarkM31
author_rank: Contributor
timestamp: November 26, 2021, 10:31:37 pm
content: Howdy,I actually used a 260 for work, way back in the 80s, Having been using it, I much prefer a DMM if it had a manual range switches and mine worked more accurately on capacitance.But yes, getting my mind right is getting back to the troubleshooting mindset.Merci, gracias and Danke.