On 2023/04/18 9:40 a.m., Tony Duell wrote:
On Tue, Apr 18, 2023 at 2:51 PM Tom Hunter via cctalk
<cctalk@classiccmp.org> 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"
