On Tue, Apr 18, 2023 at 2:51 PM Tom Hunter via cctalk <cctalk(a)classiccmp.org> wrote: As soon as I saw 'Boschert' mental alarm bells triggered.... Boschert made a particularly unfriendly (to the repairer) type of SMPSU which I call the '2 stage'. I can explain how it works if necessary, but be warned that with one of those if a particular power transistor fails (and it often does), it takes out a couple of other power transistors, the current sense resistor, numerous small transistors, the regulator chip, the fuse and sometime PCB tracks. They're not all like that, but I will agree that a burnt-out resistor in an SMPSU nearly always means other components have failed. It's likely the same PSU was used in other devices, you might want to look through all the service manuals you can find to see if it turns up. Can you make a photo of the PSU available somewhere in case somebody recognises it. -tony

On 2023/04/18 9:40 a.m., Tony Duell wrote: I like to start with schematics before poking too much... Photo of the SMPSU: https://www.flippers.com/images/ADM31_Terminal/Boschert_1001_ADM31_PowerSup… Burnt Resistor: https://www.flippers.com/images/ADM31_Terminal/Boschert_1001_ADM31_PowerSup… Schematics preferred, under the power supply is one I found on bitsavers for a slightly later model terminal. If needed I will draw them up myself, I just don't want to spend a couple of hours sketching it out if I can find a proper drawing. I assume bad caps (will replace with low-ESR high temp), and possibly blown transistor(s)... *And Gregory Beat sent me a link that covers the 1001 SMPS very neatly:* http://www.bitsavers.org/pdf/boschert/Boschert_OL25_Single-Stage_Power_Supp… and it was buried on bitsavers - where I went before bothering the list! Thanks folks! John :-#)# -- John's Jukes Ltd. 7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 Call (604)872-5757 (Pinballs, Jukes, Video Games) flippers.com "Old pinballers never die, they just flip out"

On Tue, Apr 18, 2023 at 3:16 PM Fred Cisin via cctalk <cctalk(a)classiccmp.org> wrote: That's only true with Commodore 64's. Sellam

On 4/18/23 18:37, Tom Hunter via cctalk wrote: A friend who worked as a DEC CE decades ago, said that "transistor-protected fuses" was a standing joke among that community. --Chuck

On 2023/04/18 8:48 p.m., Tony Duell via cctalk wrote: In the end replacing the capacitors got the supply running. And I checked the resistor that looked overheat, and it was 34R which is within 15% of the value shown on another 1001 supply that is close to the one (same part numbers and values for a number of the parts) in my ADM31. The supply puts out +5VDC, +17VDC (unreg), -17VDC (unreg), and 70VDC (unreg). The board appears to work - I have 5VDC on the MB, and I get a BEEP, and there is some sort of data happening on the DB and I am getting data on the Vertical, Horizontal, and Video signals to the monitor. Monitor isn't lighting up - no HV (I've recapped it too), so I have to put on my monitor hat next. Stay tuned if interested... Oh, I am missing two key caps for the ADM31, anyone have spares? Not sure what is printed on them at this point, but any caps would be better than missing ones to start! Thanks, John :-#)# -- John's Jukes Ltd. 7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 Call (604)872-5757 (Pinballs, Jukes, Video Games) flippers.com "Old pinballers never die, they just flip out"

On 2023/04/23 3:16 p.m., Glen Slick via cctalk wrote: As I remember (machine is at shop, and I'm not) I am missing the top row far left - DEL/CHAR/INS - and the top row right of that section - SKIP. I need to confirm on Tuesday, but that link is a major help! Thanks, John :-#)# -- John's Jukes Ltd. 7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 Call (604)872-5757 (Pinballs, Jukes, Video Games) flippers.com "Old pinballers never die, they just flip out"