> Hi Jens, > > I know this is not a chip-related question, but it's semiconductors, so > it's at least half on-topic. > > I'm repairing my Hameg HM604 oscilloscope, it's not switching off the beam > on backtrace and during wait-for-trigger. I checked transistors in the > intensity control area (I have no schematics), and found one transistor > with funny behaviour - I can measure three diodes, so I'm pretty sure this > one is in silicon Nirwana.
I have the HM605 with schematic. Perhaps there is some similarity. As for the BF311, now your received 2 different pinouts: Declan's and Pieter's. Pieter's pinout is the same as in my databook. But in my databook the oblique edge is on top instead of on side as at your image. In the schematic of the 605 the fly back suppresionpuls is coupled to the cathode circuit of the CRT, which is at high negative voltage, by an opto coupler. The output of the opto coupler is amplified by a complementary pair (BF440 (PNP) and BF199 (NPN)) and given to the cathode. I will not be difficult to find a replacement to this transistor. The typical transition frequency is 750 MHz. The max voltages are rather low. Gr�sze, Harry > > The question I have is about the pinuot of this type, and how they marked > the parts back then: > > http://think42.com/bf311.jpg > > Both these transistors come out of the oscilloscope. The right one behaves > correctly, assuming that the base is the right pin (I can measure two > diodes to that pin, and the other two have no connection in either > direction, which is correct for TO92Z package). The left one has diodes > between all pins (not shorts!), so I assume it's dead. The question is: Why > has the TFK one (left on the picture) blue paint on top? Why did Hameg use > different manufacturers for same-type transistors? There is no other > transistor with blue marking on top, and it did not look like this one has > been exchanged before (except someone did a *very* clean repair job). Is it > some marking to distinguish between TO92 (CBE pinout) and TO92Z (ECB pinout)?? > > I did not find any reliable data using Google, only some places that say > this type is obsolete. Any help in finding the right replacement is > appreciated. > > ciao, > -- > Jens Sch�nfeld > > -- > Author: Jens =?iso-8859-1?Q?Sch=F6nfeld?= > INET: [EMAIL PROTECTED] > > Fat City Hosting, San Diego, California -- http://www.fatcity.com > --------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > the message BODY, include a line containing: UNSUB CHIPDIR-L > (or the name of mailing list you want to be removed from). You may > also send the HELP command for other information (like subscribing). > -- Author: H.C. Croon INET: [EMAIL PROTECTED] Fat City Hosting, San Diego, California -- http://www.fatcity.com --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB CHIPDIR-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
