HP - 1741A - Page 1
Forum section: electronics / projects

author: Georg
author_rank: Newbie
timestamp: February 08, 2020, 04:15:29 pm
content: Hallo,ich lerne noch mit Oszilloskop um zugehen. Ich habe versucht im Internet zu suchen leider ohne Erfolg.Bitte um Hilfe ein HP 1741A Oszilloskop reparieren.Oszilloskop habe ich vor 3 Wochen gekauft. Ein Schalter - TIME / DIV- war mechanisch defekt. Ich habe der ausgebaut und instand gesetzt. Auf beiden Kanälen konnte ich Impulse beobachten. Zum Fall: Der Koloskop war eingeschaltet und ich habe Spannung Impulse auf B Kanal beobachtet. Wesentlich habe ich die Sonde falsch auf neu verdrahtete Spule angeklemmt. Die Spannung Spitzen habe ich noch erblickt. Schätzung weise viel zu viel, von unteren Bereich durch ganzen Bildschirm weit hinaus. Und das war, seid dem ist nur Kanal A OK. ich habe den zerlegt. Nach einigen zufälligen Messpunkten habe ich bemerkt, dass die Spannungen tlw sind. außer Toleranz. Von einigen Volt bis zu 40 Volt zu viel. Eine Zener (?) Diode stad 100V hatte 141V. Die habe ich raus gelötet, weil die Lötstelle war dunkel Braun (überhitzt). Ergebnis-beide Richtungen hochohmig, A komplett gesperrt und B nach 2-3 Sekunden schaltet um und zeigt 25-32 Mohm, und danach wieder schaltet um in sperre. Ich vermute das 2 Elemente sind defekt.1-Doppelt-Transistor (?) 5-217 7732CIMG_20200205_124833 kj.jpg2 - Transistor (Motorola?) 712 3-380Kennen Sie mir helfen Ersatz Teil zu finden?MfGGeorg

author: tggzzz
author_rank: Super Contributor
timestamp: February 08, 2020, 05:11:24 pm
content: English please!Google translate gives...Hi there,I'm still using an oscilloscope to go. I tried to search the Internet unfortunately without Erfolg.Bitte help an HP 1741A oscilloscope repair.Oscilloscope I bought weeks before the third A switch - TIME / DIV was mechanically defective. I have the expanded and repaired. On both channels I could watch impulses. For instance: The colonoscope was on and I have observed voltage pulses on B channel. I have much the probe clamped incorrectly re-wired coil. The spikes I have yet seen. Estimate as too much of a low level from full screen far beyond. And that was, you are the only channel A OK. I have the split. After some random measurement points I've noticed that the tensions are partly. out of tolerance. Of a few volts up to 40 volts too much. A Zener (?) Diode stad 100V 141V had. I get soldered because the solder joint was dark brown (overheated). Results both directions high impedance, A and B completely blocked after 2-3 seconds is toggled to indicate 25-32 Mohm, and then again switches to lock. I suspect the two elements are defective.1 Double-transistor (?) 5-217 7732CIMG_20200205_124833 kj.jpg2 - (? Motorola) transistor 712 3-380Do you know help me find spare part?Kind regardsGeorg

author: DuPe
author_rank: Regular Contributor
timestamp: February 08, 2020, 06:32:59 pm
content: Even though being german native speaker: I also have serious problems to understand the original post

author: Georg
author_rank: Newbie
timestamp: February 08, 2020, 08:07:07 pm
content: Hi,Repair an HP 1741A oscilloscope for help.I bought the osciloscope 3 weeks ago. One switch - TIME / DIV - was mechanically defective. I have expanded and repaired it. I saw impulses on both channels. In the case: The oscilloscope was switched on and I observed voltage pulses on B Knnal. Essentially, I incorrectly clamped the probe onto the rewired coil. I can still see the spikes. Appreciate far too much, from the bottom to the full screen far beyond. And that was, that's just channel A OK. I took it apart. After a few random measurement points, I noticed that the voltages are low. out of tolerance. From a few volts to 40 volts too much. A zener diode?I suspect the 2 elements are defective.1-Dopelt tranzistor (?) 5-217 7732C2 - Tranzistor (Motorola?) 712 3-380Do you know that I help replace names?greetingsGeorg Schab

author: DuPe
author_rank: Regular Contributor
timestamp: February 08, 2020, 10:27:44 pm
content: you can download the service manual from keysight:https://www.keysight.com/en/pd-1741A%3Aepsg%3Apro-pn-1741A/100-mhz-dual-channel-storage-scope?pm=PL&nid=-536900196.536896504&cc=GB&lc=engTherein you should find all needed information.

author: Martin.M
author_rank: Frequent Contributor
timestamp: February 10, 2020, 04:33:43 pm
content: killed the input stage CH.B?1850-0266 Dual Fet.