[cctalk] Re: Schematics for Lear Siegler ADM31?
On 2023/04/23 3:16 p.m., Glen Slick via cctalk wrote: On Sun, Apr 23, 2023 at 3:10 PM John Robertson via cctalk wrote: 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! Keyboard photo to see what key caps are missing: https://terminals-wiki.org/wiki/index.php/Lear_Siegler_ADM-31 https://terminals-wiki.org/wiki/images/2/29/Lear_Siegler_ADM-31_321477505131-3.jpg 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"
[cctalk] Re: Schematics for Lear Siegler ADM31?
On Sun, Apr 23, 2023 at 3:10 PM John Robertson via cctalk wrote: > > 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! Keyboard photo to see what key caps are missing: https://terminals-wiki.org/wiki/index.php/Lear_Siegler_ADM-31 https://terminals-wiki.org/wiki/images/2/29/Lear_Siegler_ADM-31_321477505131-3.jpg
[cctalk] Re: Schematics for Lear Siegler ADM31?
On 2023/04/18 8:48 p.m., Tony Duell via cctalk wrote: On Wed, Apr 19, 2023 at 2:37 AM Tom Hunter via cctalk wrote: ... or four $20 power transistors to protect a 10 cent fuse like on the DEC VR-14 display. In general the transistor(s) will fail short-circuit, thus taking out the fuse too. Some switch-mode power supplies use special fast-acting fuses which can actually be more expensive than the chopper transistor. -tony 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"
[cctalk] Re: Schematics for Lear Siegler ADM31?
On Tue, Apr 18, 2023 at 11:04 PM John Robertson via cctalk wrote: > > I like to start with schematics before poking too much... So do I. > > 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_Supply_Maintenance_Manual_May79.pdf > > and it was buried on bitsavers - where I went before bothering the list! That is clearly not one of the '2 stage' ones that fail in spectacular ways. It's a relatively conventional SMPSU and shouldn't be too hard to sort out. -tony > > Thanks folks! > > John :-#)# > > > > > > > > >> On Tue, Apr 18, 2023 at 12:20 AM John Robertson via cctalk < > >> cctalk@classiccmp.org> wrote: > >> > >>> I've checked bitsavers.org (Al does a great job!), and a number of > >>> forums, but no luck finding schematics for my ADM31 that I am trying to > >>> resurrect. The power supply has issues and I need to identify a blown > >>> out resistor - the switching supply is a Boschert model 1001 date code > >>> 7943 Revision J. > >>> > >>> 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" > >>> > >>> > > -- >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" >
[cctalk] Re: Schematics for Lear Siegler ADM31?
On Wed, Apr 19, 2023 at 2:37 AM Tom Hunter via cctalk wrote: > > ... or four $20 power transistors to protect a 10 cent fuse like on the DEC > VR-14 display. In general the transistor(s) will fail short-circuit, thus taking out the fuse too. Some switch-mode power supplies use special fast-acting fuses which can actually be more expensive than the chopper transistor. -tony
[cctalk] Re: Schematics for Lear Siegler ADM31?
On 4/18/23 18:37, Tom Hunter via cctalk wrote: > ... or four $20 power transistors to protect a 10 cent fuse like on the DEC > VR-14 display. A friend who worked as a DEC CE decades ago, said that "transistor-protected fuses" was a standing joke among that community. --Chuck
[cctalk] Re: Schematics for Lear Siegler ADM31?
... or four $20 power transistors to protect a 10 cent fuse like on the DEC VR-14 display. Tom On Wed, 19 Apr 2023, 6:16 am Fred Cisin via cctalk, wrote: > On 2023/04/18 9:40 a.m., Tony Duell wrote: > > The blown out resistor likely has "blown out" for a reason. > > The replacement will probably suffer the same faith unless you find the > > root cause. > > Isn't there usually a larger, more critical component, such as a > proprietary microprocessor, to blow out to protect the resistor? > >
[cctalk] Re: Schematics for Lear Siegler ADM31?
On Tue, Apr 18, 2023 at 3:16 PM Fred Cisin via cctalk wrote: > On 2023/04/18 9:40 a.m., Tony Duell wrote: > > The blown out resistor likely has "blown out" for a reason. > > The replacement will probably suffer the same faith unless you find the > > root cause. > > Isn't there usually a larger, more critical component, such as a > proprietary microprocessor, to blow out to protect the resistor? > That's only true with Commodore 64's. Sellam
[cctalk] Re: Schematics for Lear Siegler ADM31?
On 2023/04/18 9:40 a.m., Tony Duell wrote: The blown out resistor likely has "blown out" for a reason. The replacement will probably suffer the same faith unless you find the root cause. Isn't there usually a larger, more critical component, such as a proprietary microprocessor, to blow out to protect the resistor?
[cctalk] Re: Schematics for Lear Siegler ADM31?
On 2023/04/18 9:40 a.m., Tony Duell wrote: On Tue, Apr 18, 2023 at 2:51 PM Tom Hunter via cctalk wrote: The blown out resistor likely has "blown out" for a reason. The replacement will probably suffer the same faith unless you find the root cause. 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 I like to start with schematics before poking too much... Photo of the SMPSU: https://www.flippers.com/images/ADM31_Terminal/Boschert_1001_ADM31_PowerSupply.jpg Burnt Resistor: https://www.flippers.com/images/ADM31_Terminal/Boschert_1001_ADM31_PowerSupply-burnt_resistor.jpg 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_Supply_Maintenance_Manual_May79.pdf and it was buried on bitsavers - where I went before bothering the list! Thanks folks! John :-#)# On Tue, Apr 18, 2023 at 12:20 AM John Robertson via cctalk < cctalk@classiccmp.org> wrote: I've checked bitsavers.org (Al does a great job!), and a number of forums, but no luck finding schematics for my ADM31 that I am trying to resurrect. The power supply has issues and I need to identify a blown out resistor - the switching supply is a Boschert model 1001 date code 7943 Revision J. 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" -- 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"
[cctalk] Re: Schematics for Lear Siegler ADM31?
On 4/18/23 09:40, Tony Duell via cctalk wrote: > On Tue, Apr 18, 2023 at 2:51 PM Tom Hunter via cctalk > wrote: >> >> The blown out resistor likely has "blown out" for a reason. >> The replacement will probably suffer the same faith unless you find the >> root cause. > > > 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. True, but Bob Boschert was a pioneer in the field working with what components were available. So don't be too hard on him. --Chuck
[cctalk] Re: Schematics for Lear Siegler ADM31?
On Tue, Apr 18, 2023 at 2:51 PM Tom Hunter via cctalk wrote: > > The blown out resistor likely has "blown out" for a reason. > The replacement will probably suffer the same faith unless you find the > root cause. 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 Tue, Apr 18, 2023 at 12:20 AM John Robertson via cctalk < > cctalk@classiccmp.org> wrote: > > > I've checked bitsavers.org (Al does a great job!), and a number of > > forums, but no luck finding schematics for my ADM31 that I am trying to > > resurrect. The power supply has issues and I need to identify a blown > > out resistor - the switching supply is a Boschert model 1001 date code > > 7943 Revision J. > > > > 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" > > > >
[cctalk] Re: Schematics for Lear Siegler ADM31?
I’ve found that following traces and identifying components that connect to either side of the failed resistor is usually a good start for finding root cause. Shorted power transistors, diodes, or portions of bridge rectifiers have been the root cause of cascading failures in my cases. -Royce > On Apr 18, 2023, at 06:51, Tom Hunter via cctalk > wrote: > > The blown out resistor likely has "blown out" for a reason. > The replacement will probably suffer the same faith unless you find the > root cause. > >> On Tue, Apr 18, 2023 at 12:20 AM John Robertson via cctalk < >> cctalk@classiccmp.org> wrote: >> >> I've checked bitsavers.org (Al does a great job!), and a number of >> forums, but no luck finding schematics for my ADM31 that I am trying to >> resurrect. The power supply has issues and I need to identify a blown >> out resistor - the switching supply is a Boschert model 1001 date code >> 7943 Revision J. >> >> 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" >> >>
[cctalk] Re: Schematics for Lear Siegler ADM31?
The blown out resistor likely has "blown out" for a reason. The replacement will probably suffer the same faith unless you find the root cause. On Tue, Apr 18, 2023 at 12:20 AM John Robertson via cctalk < cctalk@classiccmp.org> wrote: > I've checked bitsavers.org (Al does a great job!), and a number of > forums, but no luck finding schematics for my ADM31 that I am trying to > resurrect. The power supply has issues and I need to identify a blown > out resistor - the switching supply is a Boschert model 1001 date code > 7943 Revision J. > > 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" > >
[cctalk] Re: Schematics for Lear Siegler ADM31?
Why don’t you post a picture of the board and see if anyone can id the resistor from an intact Adm31 they already own? Sent from my iPhone > On Apr 17, 2023, at 09:20, John Robertson via cctalk > wrote: > > I've checked bitsavers.org (Al does a great job!), and a number of forums, > but no luck finding schematics for my ADM31 that I am trying to resurrect. > The power supply has issues and I need to identify a blown out resistor - the > switching supply is a Boschert model 1001 date code 7943 Revision J. > > 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" >
