Documentation for restoring a PM3261 - Page 1
Forum section: electronics / repair

author: PlatinumX
author_rank: Newbie
timestamp: November 24, 2015, 08:23:01 am
content: Hi! I just bought a Phillips PM3261 to restore, and while I found a PM3260 service manual, it's a bit different from mine.I haven't gotten deep into the guts yet, but just based on the controls, the areas that are missing from the documentation are:Event Counter - this is broken on mine, or I don't know how to use it.Digital Delay - this is also broken and/or too mysterious for me. All it does is turn off the delay mode.If anyone has any info or documentation that could help, that would be great!

author: tautech
author_rank: Super Contributor
timestamp: November 24, 2015, 09:29:32 am
content: Welcome to the forum.This might be close, it's for the 3262:http://www.ebaman.com/index.php/remository/ELECTRONICS/Test-Equipment/Fluke-Philips/Scopes/Philips-PM3262-User-and-Service-Manuals/There's also the 3261 supplement that's easy to find:http://www.apite.com/apitewww/pedido.php?modelo=UE0zMjYx&documentacion=285126&pdf=20622101.pdf&marca=MjYw

author: lowimpedance
author_rank: Super Contributor
timestamp: November 24, 2015, 10:55:56 am
content: Will upload the scans when back at work tomorrow!.

author: lowimpedance
author_rank: Super Contributor
timestamp: November 24, 2015, 10:33:46 pm
content: Okay the scans are from the PM3261 handbook but not the whole book just the schematic, parts overlay, some operating instructions etc.Check the quality is good enough.I can do higher dpi scans if needed and also more of the handbook if needed, (note ; its quite a bit more to scan which is why I did not do the whole thing!).edit: I should point out that the old CRO at work was labeled PM3261, the handbook's supplied were for the PM3260 main frame and the PM3261 supplement !.

author: PlatinumX
author_rank: Newbie
timestamp: November 25, 2015, 08:54:38 am
content: Wonderful! Thanks so much, lowimpedance. I'll try my best to document the repair and let you all know how it goes.

author: PlatinumX
author_rank: Newbie
timestamp: November 26, 2015, 07:45:48 am
content: Just took my first crack at it. My board doesn't quite match the diagram and has quite a bit of rework - cut traces, additional components, etc. I suspect it is from an early production run (date codes are all circa 1975).I found the following:Probed voltages in circuit and found that the +5V rail was at 0.81V while +6V rail was at 5.86V. Measured about 319 ohms from +5 to ground, so I suspected a bad diode. Took the board out and removed the diode (GR2401) and it tested good. Took out C2406 and C2308 and tested capacitance and leakage resistance, tested good. Put the diode and caps back in and re-installed delay board to do additional probing, and found +5V is now 4.92V and counter now turns on.Tried to perform delay calibration per section 3.1 of lowimpedance's PM3261-c.pdf. Found that the count knob push-pull had dirty contacts, which was leaving it in "fast" mode and couldn't hit the count speed spec (item 7). Blew it out with compressed air and it now works much better. Now meets spec at 15.5 seconds / 10 count.My guess as to how this is supposed to work is it just delays the display by N trigger events (N being from 0-9999 as displayed on the counter). This is similar to how the "Delay Time" knob works, but it's better because it's can scan through data(?) There's a press release describing it here:http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=5183165.However, I only get a trigger when the counter is 0 or 1. Outside this range the "NOT TRIG'D" light comes on and sweep stops if displaying the delayed timebase, or the trace highlight goes away if displaying main TB.I think I need to understand Fig 3.5 of PM3261-c.pdf more fully before continuing.

author: PlatinumX
author_rank: Newbie
timestamp: November 28, 2015, 05:16:31 am
content: @lowimpedance, could you do me a favor and get a high-DPI scan of Page 28, Fig. 3.1 as shown in the attachment?It looks to me like the delay board is now working as expected, but it's not seeing trigger pulses from the delayed trigger time base. It looks like they reworked in a transistor to generate the pulses, but it's not shown in the circuit diagrams I have and I suspect it's lost a wire.I've shared all the documents I have here:https://drive.google.com/folderview?id=0B3jtpt2_4iKFSnY2VFN1Q2NlV0U&usp=sharing

author: lowimpedance
author_rank: Super Contributor
timestamp: December 03, 2015, 11:56:41 pm
content: Higher DPI scan of fig 3.1 as requested. (jpg) Hope it has enough resolution.Forum limited to 1M per upload !!

author: Chris56000
author_rank: Frequent Contributor
timestamp: June 25, 2023, 09:21:54 pm
content: Can anybody post the whole of the PM3261 supplement please?It would cost me over £100 in postage to buy one from the USA, and I object to paying three figures in postage for a manual that isn't very thick!What's been posted isn't anywhere what I need as the logic PCBs on my pm3261 have been butchered by somebody trying to de–solder it with what looks like a poker and I need the whole supplement to help with making a new PCB for it!Chris Williams

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: June 25, 2023, 11:07:49 pm
content: This company has really good scans and has the PM 3262 but I don't know if your supplement is included.Perhaps e mail them and ask.http://artekmanuals.com/manuals/other-manuals/

author: Chris56000
author_rank: Frequent Contributor
timestamp: June 26, 2023, 01:10:32 am
content: I've already bought a set of three manuals that included an original paper PM3262 one – Artek don't list the PM3261, which is what I need – as I said previously I object to paying U.S. sellers grossly over–inflated three–figure postage prices when I have had a 465B manual imported from the USA for less than £20 postage only last year, so ONE seller at least, took the effort to find the shipping cost out and price fairly!I wouldn't be asking on here in the first place if Artek had what I needed or I found one to buy in the UK – if Artek had it I would have bought it from them, or bought it from a UK seller – if I ask on here for a specific model, it's because I've already spent a considerable amount of time looking for one, emailing suppliers (including Artek!) and checking those who do list Philips manuals – there's a German eBay seller that's scraped practically every free Philips manual there is, and charges quite high prices for them, rest assured you won't find any of his listings that not already available for free elsewhere!

author: Chris56000
author_rank: Frequent Contributor
timestamp: June 30, 2023, 10:36:12 pm
content: I (eventually!) was able to buy a PM3260 Manual with the 37 page PM3261 Supplement included on the Jetec Website!http://www.jetecnet.com/Chris Williams