Hi Lou, I believe that the transistors are good. If they do not run to hot to hold on to. Yes CR105 feeds the negative supply. Did you check CR104 and CR105? Q203 and Q204 should also be check since they could shunt the transformer. Is transformer T202 and T203 hot. The high voltage windings on T202 could be leaky. Try taking out C119, did rails go to approximately 15 volts? Time to start isolating the supplies to various circuits to find the culprit by removing one leg of various resistors. You can deal with the carbon resistor accuracies later. I had all many issues with my meter, after all their very old. Dallas On 6/7/2016 11:09 PM, Lou Amadio wrote: > Hi Dallas > I set my DMM on Diode Check mode: > Q201, PNP, no part number: EB/BE=0.23/Hi, CB/BC=0.21/Hi, EC/CE=Hi/Hi > Q202, PNP, no part number: EB/BE=0.22/Hi, CB/BC=0.20/Hi, EC/CE=Hi/Hi > Q111, NPN, 2N1304: EB/BE=Hi/0.28, CB/BC=Hi/0.26, EC/CE=Hi/Hi > Q112, PNP, 2N1305: EB/BE=0.26/Hi, CB/BC=0.25/Hi, EC/CE=Hi/Hi > > The two 15v rails are down to about 5v each. The oscillator is working but > fluctuating badly on frequency. > Replaced all the electro caps. Have not replaced the resistors or diodes. > Will check these next. > > CR105 feeds the neg 15v supply cap?? > Regards > Lou >

Hi Dallas Thanks for all the replies. Hope I am not inconveniencing you too much. Q203, NPN, 2N1304: EB/BE=Hi/0.23, CB/BC=Hi/0.24, EC/CE=Hi/Hi Q204, NPN, 2N1304: EB/BE=Hi/0.27, CB/BC=Hi/0.25, EC/CE=Hi/Hi Checked all diodes on both PCBs - all OK. Nothing getting hot anywhere. C119 is now a link feeding the LEDs, which illuminate BTW. So, some output from T202 at least Still, I am beginning to suspect transformer T202, but how do I test it? Next step is to disconnect the power supply PCB from the main board and see if I can get +-15v with no other load. Regards Lou On Wed, Jun 8, 2016 at 3:24 PM, Dallas Smith <dosmith@outlook.com> wrote: > Hi Lou, > > I believe that the transistors are good. If they do not run to hot to hold > on to. > Yes CR105 feeds the negative supply. Did you check CR104 and CR105? > Q203 and Q204 should also be check since they could shunt the transformer. > Is transformer T202 and T203 hot. The high voltage windings on T202 could > be leaky. > Try taking out C119, did rails go to approximately 15 volts? > Time to start isolating the supplies to various circuits to find the > culprit by removing one leg of various resistors. > You can deal with the carbon resistor accuracies later. > I had all many issues with my meter, after all their very old. > > Dallas > > On 6/7/2016 11:09 PM, Lou Amadio wrote: > >> Hi Dallas >> I set my DMM on Diode Check mode: >> Q201, PNP, no part number: EB/BE=0.23/Hi, CB/BC=0.21/Hi, EC/CE=Hi/Hi >> Q202, PNP, no part number: EB/BE=0.22/Hi, CB/BC=0.20/Hi, EC/CE=Hi/Hi >> Q111, NPN, 2N1304: EB/BE=Hi/0.28, CB/BC=Hi/0.26, EC/CE=Hi/Hi >> Q112, PNP, 2N1305: EB/BE=0.26/Hi, CB/BC=0.25/Hi, EC/CE=Hi/Hi >> >> The two 15v rails are down to about 5v each. The oscillator is working but >> fluctuating badly on frequency. >> Replaced all the electro caps. Have not replaced the resistors or diodes. >> Will check these next. >> >> CR105 feeds the neg 15v supply cap?? >> Regards >> Lou >> >> > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. >

Hi Lou, I think we should talk to each other. Send me your phone number to dosmith@outlook.com. I'm confused to the state your meter is in, you already made the mod and now you are having problems? Or it's not working before the mod? When I made my mod it pulled the rails to ±14 volts. It was a compromise between brightness and performance. I tried many LED's and the ones I selected were just right. The right brightness to current draw and the correct wavelength for the photo cells. My instructions are not as clear as it should be for the T202 move wire from pin 9 to 7. The high voltage winding are abandoned and the led's are powered by the winding that supply the ±15 volts. I may have to look at my meter to see better what was done. I work second shift, whats a good time to talk? I go to work at 3pm and return at midnight. Dallas On 6/8/2016 1:24 AM, Dallas Smith wrote: > Hi Lou, > > I believe that the transistors are good. If they do not run to hot to > hold on to. > Yes CR105 feeds the negative supply. Did you check CR104 and CR105? > Q203 and Q204 should also be check since they could shunt the > transformer. > Is transformer T202 and T203 hot. The high voltage windings on T202 > could be leaky. > Try taking out C119, did rails go to approximately 15 volts? > Time to start isolating the supplies to various circuits to find the > culprit by removing one leg of various resistors. > You can deal with the carbon resistor accuracies later. > I had all many issues with my meter, after all their very old. > > Dallas > > On 6/7/2016 11:09 PM, Lou Amadio wrote: >> Hi Dallas >> I set my DMM on Diode Check mode: >> Q201, PNP, no part number: EB/BE=0.23/Hi, CB/BC=0.21/Hi, EC/CE=Hi/Hi >> Q202, PNP, no part number: EB/BE=0.22/Hi, CB/BC=0.20/Hi, EC/CE=Hi/Hi >> Q111, NPN, 2N1304: EB/BE=Hi/0.28, CB/BC=Hi/0.26, EC/CE=Hi/Hi >> Q112, PNP, 2N1305: EB/BE=0.26/Hi, CB/BC=0.25/Hi, EC/CE=Hi/Hi >> >> The two 15v rails are down to about 5v each. The oscillator is >> working but >> fluctuating badly on frequency. >> Replaced all the electro caps. Have not replaced the resistors or >> diodes. >> Will check these next. >> >> CR105 feeds the neg 15v supply cap?? >> Regards >> Lou >> > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > >

Hi Dallas So sorry. I understand how confusing it can be coming in part way through a repair. My apology. I have managed to implement your LEDs mod and I can see the LEDs light up but the voltage driving them, and the rest of the meter, is way too low. The history of my 845 can be found here: http://www.eevblog.com/forum/metrology/teardown-fluke-845aabar-tweaks-and-mods-%28and-repairs%29/.You will need to scroll down somewhat. Briefly, When I first received the 845 it was not working and had nicad corrosion on the PS PCB. I have not really gotten it going properly yet. I then started on your LED mod hoping that would help, spurred on when I discovered the neons had turned black. So, I am now back to square one and working on getting a stable +-15v.I have managed to separate the PS and Main PCBs and will conduct experiments on the PS by emulating CR104/105, C117/118 off board. I live on the east coast of Australia, near Sydney. Regards, Lou On Thu, Jun 9, 2016 at 3:19 AM, Dallas Smith <dosmith@outlook.com> wrote: > Hi Lou, > > I think we should talk to each other. Send me your phone number to > dosmith@outlook.com. > > I'm confused to the state your meter is in, you already made the mod and > now you are having problems? Or it's not working before the mod? When I > made my mod it pulled the rails to ±14 volts. It was a compromise between > brightness and performance. I tried many LED's and the ones I selected were > just right. The right brightness to current draw and the correct wavelength > for the photo cells. My instructions are not as clear as it should be for > the T202 move wire from pin 9 to 7. The high voltage winding are abandoned > and the led's are powered by the winding that supply the ±15 volts. I may > have to look at my meter to see better what was done. > > I work second shift, whats a good time to talk? I go to work at 3pm and > return at midnight. > > Dallas > > > On 6/8/2016 1:24 AM, Dallas Smith wrote: > >> Hi Lou, >> >> I believe that the transistors are good. If they do not run to hot to >> hold on to. >> Yes CR105 feeds the negative supply. Did you check CR104 and CR105? >> Q203 and Q204 should also be check since they could shunt the transformer. >> Is transformer T202 and T203 hot. The high voltage windings on T202 could >> be leaky. >> Try taking out C119, did rails go to approximately 15 volts? >> Time to start isolating the supplies to various circuits to find the >> culprit by removing one leg of various resistors. >> You can deal with the carbon resistor accuracies later. >> I had all many issues with my meter, after all their very old. >> >> Dallas >> >> On 6/7/2016 11:09 PM, Lou Amadio wrote: >> >>> Hi Dallas >>> I set my DMM on Diode Check mode: >>> Q201, PNP, no part number: EB/BE=0.23/Hi, CB/BC=0.21/Hi, EC/CE=Hi/Hi >>> Q202, PNP, no part number: EB/BE=0.22/Hi, CB/BC=0.20/Hi, EC/CE=Hi/Hi >>> Q111, NPN, 2N1304: EB/BE=Hi/0.28, CB/BC=Hi/0.26, EC/CE=Hi/Hi >>> Q112, PNP, 2N1305: EB/BE=0.26/Hi, CB/BC=0.25/Hi, EC/CE=Hi/Hi >>> >>> The two 15v rails are down to about 5v each. The oscillator is working >>> but >>> fluctuating badly on frequency. >>> Replaced all the electro caps. Have not replaced the resistors or diodes. >>> Will check these next. >>> >>> CR105 feeds the neg 15v supply cap?? >>> Regards >>> Lou >>> >>> >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> >> >> > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. >