UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Clansman IBMS

Sparky67 · 2nd Oct 2018, 9:47 pm

This fault turned out to be a s/c 10uF 25V tantalum cap on the 15V rail on the IBMU analogue board, which was dragging the +/-15V supplies down. These are supplied from the same IBEK DC-DC converter. Fortunately it survived and the unit is now back to normal.

Not the easiest of units to work on. The front panel is attached by a short ribbon cable one end and a 'flexi-rigid loom' the other, and has to be connected to get DC into the box and for the fault display to work, so the boards behind it can't easily be brought out on extender cards. I ended up testing the PSU out of the box on the bench, then soldering wires onto the voltage outputs of the 5 and 15V converters to be able to measure those externally and pulled the boards (with the power off) until the volts came back up. A DVM did the rest.

Also one edge connector is fitted reversed to the rest, which had me scratching my head when following the 28V supply paths initially. So pin 1 on one board becomes pin 32 on the next. Mmmm...

Martin
G4NCE

2nd Oct 2018, 9:47 pm	#6
Sparky67 Heptode Join Date: Feb 2008 Location: Great Barr, Sandwell, West Midlands, UK. Posts: 589	Re: Clansman IBMS - Low Volts Fault This fault turned out to be a s/c 10uF 25V tantalum cap on the 15V rail on the IBMU analogue board, which was dragging the +/-15V supplies down. These are supplied from the same IBEK DC-DC converter. Fortunately it survived and the unit is now back to normal. Not the easiest of units to work on. The front panel is attached by a short ribbon cable one end and a 'flexi-rigid loom' the other, and has to be connected to get DC into the box and for the fault display to work, so the boards behind it can't easily be brought out on extender cards. I ended up testing the PSU out of the box on the bench, then soldering wires onto the voltage outputs of the 5 and 15V converters to be able to measure those externally and pulled the boards (with the power off) until the volts came back up. A DVM did the rest. Also one edge connector is fitted reversed to the rest, which had me scratching my head when following the 28V supply paths initially. So pin 1 on one board becomes pin 32 on the next. Mmmm... Martin G4NCE