Notifications
Clear all

Free Philips PM3110 oscilloscope FOC

 
sideband
(@sideband)
Famed V-Ratter Moderator
Posts: 4045

Now I have a Tektronix scope to play with, I want to offer my old Philips PM3110 analogue scope to anyone who wants it. It needs some TLC starting possibly with a good clean-up. This scope has been a workhorse, firstly in the Philips workshop back in the 70's and then when everything was modernised, this one found it's way into the boot of my car and has been with me ever since.....around 1980. It spent some years with my brother in his TV workshop and then the rest of the time in my home workshop and also when I briefly ran a small service business. It's had a few repairs including a new mains transformer. I have a complete set of spare boards and a CRT for it although the spare timebase board has a fault. I can also provide a full Philips service manual for it.

The current (and latest) fault is no YA channel. I've been using it on YB. I have not yet investigated this latest fault but I suspect it lies in the beam splitter section. There are quite a large number of lockfit transistors in the X and Y amplifiers and I suspect that some of these have now started to fail. It has a hybrid Y amplifier with a couple of ECC83's in the front-end run with DC heaters.

js1024 100 0263

Screenshot taken tonight. 

It's quite heavy so not prepared to post. Collect from Croydon (PM me for full address) although I would be prepared to meet in a local area or either East or West Croydon stations.

 

ReplyQuote
Topic starter Posted : 08/07/2021 11:35 pm
Red_to_Black
(@red_to_black)
Noble V-Ratter Registered
Posts: 1745

Nice offer for someone Rich, I myself still have a Hameg HM203-6 and a Philips PM3055 from my servicing days maybe I should pass these on too, just I hate the thought of ever being without a 'scope (habit I guess) although neither has been used in anger for several years now 😊 

ReplyQuote
Posted : 08/07/2021 11:50 pm
turretslug
(@turretslug)
Honorable V-Ratter Registered
Posts: 522

That looks like a nice, useful basic 'scope there, hopefully it'll find a good home. Philips test kit of that era was sturdily enough made (though, being Philips, the term "quirky" construction was also never far away....). I'm encouraged to see that it uses the more sophisticated HF power oscillator technique to generate EHT, more reliable (not to mention safer too!) than direct mains EHT. Having said that, I'm currently rebuilding a PDA multiplier for a PM3232, a bit of an Achilles heel in Philips 'scopes generally. I liked the Philips approach to test gear circuitry, straightforward yet elegant effectiveness seemed to be a design goal. Whilst I tend to regard all-valve 'scopes as something of a penance for the true enthusiast and all-solid-state as a stable and dependable blessing, no doubt having a twin-triode as input stage would withstand the odd whoopsie better than the exoticum FETs often found in Y-amp inputs.

ReplyQuote
Posted : 09/07/2021 8:47 pm
sideband
(@sideband)
Famed V-Ratter Moderator
Posts: 4045
Posted by: @turretslug

That looks like a nice, useful basic 'scope there, 

It certainly is and it's been very reliable. I suppose in truth I've just got fed up with it. It's getting on for 50 years old, it's heavy and takes up a lot of room. It probably only gets switched on twice a year and it has limited bandwidth. It's absolutely fine with what it was designed for and for the technology of the time.....typically analogue audio and video. I have managed to scope a fault on a CD player with it but triggering the waveform was very difficult and the scope really wasn't fast enough to resolve it properly. It's been absolutely fine for general scope work on monochrome and analogue colour TV though. 

The latest fault is probably one of the lockfit transistors in the beam splitter circuit. When selecting YA the beam appears right at the bottom of the screen and can't be moved up. It then gradually disappears altogether. It shouts out as a DC shift problem but I just can't muster the enthusiasm to investigate further.

The Tektronix replacement scope is a fraction of the weight, takes up virtually no bench space at all and has a vastly superior spec. 

 

ReplyQuote
Topic starter Posted : 09/07/2021 10:54 pm
turretslug
(@turretslug)
Honorable V-Ratter Registered
Posts: 522
Posted by: @sideband

The latest fault is probably one of the lockfit transistors in the beam splitter circuit. When selecting YA the beam appears right at the bottom of the screen and can't be moved up. It then gradually disappears altogether. It shouts out as a DC shift problem but I just can't muster the enthusiasm to investigate further.

The Tektronix replacement scope is a fraction of the weight, takes up virtually no bench space at all and has a vastly superior spec. 

 

I had a similar sounding fault with a Hameg HM312-8 recently- both Y channels were uncontrollably offset at the edge of the screen, one had no output, the other was severely assymmetrically compressed. The beam multiplexer matrix is driven by two pairs of BF199 in common-base mode, emitters driven by 733 gain block ICs via resistors- 3 out of 4 of these transistors were open-circuit base-emitter. The emitter feed resistors were 68 ohms- on a hunch, I checked the circuit of the early model HM203, this uses the HM312-8 circuit transplanted effectively wholesale into a "landscape" front panel rather than the "portrait" aspect panel of the '312 (complete with quaint round CRT, later '203 series got a rectangular CRT with higher sensitivity plates and considerable circuit revision). The emitter feed resistors in this later case are 150 ohms- I wondered if the 733 output with 68 ohm series resistors was delivering sufficient current to fuse the BF199 junctions with excess amplitude signals applied by the previous user and the 150 ohms was a revision to prevent this?! 4 BF199s were matched from a batch of 20 (they're only pennies), series resistors were appropriately increased and all was right as rain.

I wouldn't be surprised if Lokfits were the problem but I know what you mean about whether it's worth the effort when something better in every way is available. I do have a soft spot (probably a poor metaphor in this context....) for CRT 'scopes though....

This was just one of so many cases where I found the "diode test" facility of a DMM absolutely invaluable- some may sneer at it as not "proper" fault-finding but it's so quick and easy to go through a suspect area of a circuit and you soon get a feel for suspicious components even when in-circuit.

ReplyQuote
Posted : 10/07/2021 11:21 pm