Re: Troubleshooting HP 2116B
On Sat, 28 Jul 2018, GerardCJAT wrote: Christian, I absolutly agree with David s post. Back in the ' '70 when I was maintaining 3 x HP 2116 B running 24/24 7/7 FOR around 10 YEARS, the ONLY memory related problem that I got was traced to a faulty transistor !! Then I have a new fault ;-) After swapping the transistors with those for bit 16 (parity, not used in this machine), the fault was still there. Swapping the IC did not help. Finally, I found it: one of the two 1.65k resistors going to the outputs was bad (open). These are the collector resistors for the differential amplifier. So if I had found that resistor earlier the board would look a bit nicer than now; it is not easy at all to desolder those little 8 pin metal cans. There was a short electrolytic on one inhibit driver card, but that was fixed several days ago. This fault was obvious: the PSU was shutting off with the card in its slot. Now to the flakey bit in the other memory half. Perhaps the corresponding resistor on the other card starts to go bad? Christian
Troubleshooting HP 2116B
Christian, I absolutly agree with David s post. Back in the ' '70 when I was maintaining 3 x HP 2116 B running 24/24 7/7 FOR around 10 YEARS, the ONLY memory related problem that I got was traced to a faulty transistor !! ( But I do not recall exactly, may be it was on a Driver Inhbit Card ) Anyway, from this only one case , not statisticaly signifiant ;-)the problem was a Tx, not a C.I. Wish you the same ...
Re: Troubleshooting HP 2116B
I have other 2116 cpu manuals, getting time to do anything to find them or look for differences is a problem. On 7/27/18 4:14 AM, Christian Corti via cctalk wrote: > Ok, so I've got the computer almost running now. I now need to fix both sense > amplifier cards. One (0..4k) sometimes > reads a one for bit 3 after the machine has warmed up. The other (4..8k) has > a stuck one for bit 7. > Swapping these cards make the errors move to the other core bank respectively. > > I have the newer cards, 02116-6298, not the older 02115-6001 > The latter has CA3028A used as sense amplifiers. My card uses HP 1820-0183 > (metal can IC from RCA). I guess that it is > also a CA3028A or maybe a CA3053. Can anyone confirm this? > > Next, the manual on bitsavers (02116-9153_2116B_Vol2_Oct70, and the same as > found on the hpmuseum site) not only > contains some errors (see my other post about the front panel lamps). It has > also some badly scanned pages with parts > missing, notably page 5-50 (PDF page 350) lacks the right part of the page. > Is there a better scan available? My 1968 > copy does not list the 02116-6298. > > Christian
RE: Troubleshooting HP 2116B
Christian, I tried to track down details of the 1820-0183 and the manuals appear to say it's an RCA item, part number 80170 but I cant find anything with that number anywhere - you are probably on the right track with a CA3082A or similar. My experience in fixing similar faults on the memory boards of the 2116A was that the transistors were often leaky which created stuck bits. Sometimes I had to swap parts around between working and non-working bits to isolate the faulty items and it turned out exact replacements for the bad transistors were still available for purchase. If you're prepared to swap components around on your boards to troubleshoot, you might by lucky and find that the ICs are OK. David Collins -Original Message- From: cctalk On Behalf Of Christian Corti via cctalk Sent: Friday, 27 July 2018 9:14 PM To: cctalk@classiccmp.org Subject: Troubleshooting HP 2116B Ok, so I've got the computer almost running now. I now need to fix both sense amplifier cards. One (0..4k) sometimes reads a one for bit 3 after the machine has warmed up. The other (4..8k) has a stuck one for bit 7. Swapping these cards make the errors move to the other core bank respectively. I have the newer cards, 02116-6298, not the older 02115-6001 The latter has CA3028A used as sense amplifiers. My card uses HP 1820-0183 (metal can IC from RCA). I guess that it is also a CA3028A or maybe a CA3053. Can anyone confirm this? Next, the manual on bitsavers (02116-9153_2116B_Vol2_Oct70, and the same as found on the hpmuseum site) not only contains some errors (see my other post about the front panel lamps). It has also some badly scanned pages with parts missing, notably page 5-50 (PDF page 350) lacks the right part of the page. Is there a better scan available? My 1968 copy does not list the 02116-6298. Christian
Troubleshooting HP 2116B
Ok, so I've got the computer almost running now. I now need to fix both sense amplifier cards. One (0..4k) sometimes reads a one for bit 3 after the machine has warmed up. The other (4..8k) has a stuck one for bit 7. Swapping these cards make the errors move to the other core bank respectively. I have the newer cards, 02116-6298, not the older 02115-6001 The latter has CA3028A used as sense amplifiers. My card uses HP 1820-0183 (metal can IC from RCA). I guess that it is also a CA3028A or maybe a CA3053. Can anyone confirm this? Next, the manual on bitsavers (02116-9153_2116B_Vol2_Oct70, and the same as found on the hpmuseum site) not only contains some errors (see my other post about the front panel lamps). It has also some badly scanned pages with parts missing, notably page 5-50 (PDF page 350) lacks the right part of the page. Is there a better scan available? My 1968 copy does not list the 02116-6298. Christian
