R2600 Dead

[John-Taylor]

I have an R2600 that was working just fine, and then suddenly it starts blowing the main power fuse. The fuse blows instantly as soon as power is connected, so I suspect there is a diode gone shorted in the power supply somewhere, but without a schematic of the supply, I have no idea.
Anyone have any idea how to get at this thing to check? I saw a post when doing a search on the site for R2600 of someone that offered maintenance / service manuals, and looked at the site's .pdf, but did not figure out how to order the documents.

[Wowbagger]

Before you get too excited about the schematic, have you just looked over the power supply for bad capacitors? Capacitor plague struck all the major manufacturers, and often when the bad caps blow the power supply will start blowing fuses.

[John-Taylor]

Thanks ... I have not looked at it yet .... not even sure exactly how to get at it ... but I can get it done ...... did not know on this power supply if the AC line went to a transformer first, or if it saw diodes and capacitors directly across the line. This unit blows fuses, regardless if the unit is on or off ..... the instant power is connected, the fuse blows HARD and fast, with a "POP' ....... a shorted cap or diode across the line would certainly cause it .....
Thanks again, will figure out how to get to the power supply ....

[jry]

I would check to see if it runs on 12VDC.
That will give you a good idea if it's an input high voltage problem or a short on the low voltage output.

My guess is that it would work on 12VDC since an output short will cause an over current shutdown before it blow the fuse.

If it's blowing the fuse that quickly than the short should be easy to find with just a DVM and inspection.

[DJP126]

The R2600 series (as well as the R2000D series) has line input protection diodes that are meant to short out if your unit is connected to 220 VAC when set for 110 VAC. These diodes are known to short out when a large power surge comes down the line.

[jry]

Looks like those Varistors would pop a separate fuse on the power supply board.
My guess is the input bridge has shorted.