SX-1980 blown cement resistor R101 20W

omri617

Super Member
Hi
During the past year , I had to replace twice the cement resistor R101 on AWR-154
The symptom of the receive quit working is it had a delay turning on when levering the power switch up
No blown fuses , thermal fuse ok also
What can cause this ?
220V unit .
Note - Awr 155 & Awr 154 use different resistance but same wattage
 
Usually one of two things, either the soft start relay is not engaging at all, or it is engaging but the contacts are pitted or have a large carbon build up on them, increasing resistance between them and causing the receiver to pull power through the resistor. When it first starts up, does it click right after the power switch clicks?
 
There’s a click 4 seconds or so after switch is on.
I can’t recall hearing another one before it
 
It's only a split second before the soft start relay engages. You almost have to lay your finger on it or watch it while flipping the power switch. The click of the relay is darn near the click of the switch.
If its working correctly.
 
You could try turning it on at the wall instead of the power switch if the wall socket is quieter. You might hear the relay then? I've done that with the SPEC-4.
 
Sounds to me as the others have suggested, you need a new soft start relay. It obviously not coming on quick enough and the power is running through the resistor for too long..
 
If the soft start relay hasn't been replaced, it would be the original, and burned / resistive contacts are a certainty.

This level of resistance is hard to measure with a 2 wire DMM ohm scale.

Do yourself the favor, and replace it - it will be a LITTLE bit of work changing to 24v from the 48v circuit because the 48v relays seem to have become unavailable.
The 24v relays are plentiful and reasonably priced.



SX-1980 (for protect) DPDT pcb mount 653-my2-02-dc48
SX-1980 (soft start) 653-LY1-0-DC48 (4/20/16 edit: LY1F-DC48??)
if not available, there's 24v @ plenty of current available for a 653-LY1-0-DC24
the pcb pattern will NOT support adapting in a 48v LY2 type relay.
ALSO: WATCH YOUR HEIGHT - THE TOP OF THE RELAY IS VERY CLOSE TO THE BOTTOM COVER!!
 
I was lucky enough to get a 48V speaker and protection relay last year...You might get lucky..
 
From my restoration thread:

S1: Relay (Soft Start) ASR-046: 653-LY1-0-DC24 (Achtung! Using this relay requires you to remove R102 and run a jumper wire from the + terminal of the 3300uF 35v axial cap over to the pad of R102 that connects to pin 2. Be very careful, if you put it to the wrong side of the R102, you will short the 24v supply to the 100v supply. Not good. To be extra safe, you can just remove R102 and connect the jumper wire straight to pin 2)

The only available 48V LY1 relay has large terminals that require you to enlarge the holes on the board for the relay. Somewhat messy and doesn't look good underneath, no matter how hard you try. Definitely do the mod as Mark suggested, and it has the added bonus of removing some thermal load from the board, as R102 dissipates about 1W.
 
From my restoration thread:



The only available 48V LY1 relay has large terminals that require you to enlarge the holes on the board for the relay. Somewhat messy and doesn't look good underneath, no matter how hard you try. Definitely do the mod as Mark suggested, and it has the added bonus of removing some thermal load from the board, as R102 dissipates about 1W.
Ah yes, thats what I did!! I used your restoration thread as a resource, it is the best idea......works very well, I used your BOM, did the trick nicely.......
I ordered the 48V speaker relay and had to wait 8 weeks for it!!
 
Last edited:
I looked in my relays compartment and I found these new ones :

MY2-02 (48V) - 3 pieces
MY4-02 (24V)
LY1-0 (24V)

MY2-02 is suitable for protection
Anyone got the 48V s.s relay for sale? :$
 
I looked in my relays compartment and I found these new ones :

MY2-02 (48V) - 3 pieces
MY4-02 (24V)
LY1-0 (24V)

MY2-02 is suitable for protection
Anyone got the 48V s.s relay for sale? :$
Like the guys said, use the 24V and do the small mod, this is what I did to the one I restored, its a drop in and an easy mod...
 
I would go with the 24V relays as these mean you cna run them off the 24V power rail instead of using a resistor to drop the 80V rail to 48, which ends up giving you one very hot resistor. Heat is the biggest enemy here so I think that's another reason why converting to 24V made sense. Less heat.
 
Done. went with the 24V relay and the modification suggested. The new realys sound quieter than the old ones.
Thanks a lot
 
Nice work!! How fast does it click over after you power it on, it should be very very quick....
 
between 3 - 4 seconds I assume.
Faster than before that's for sure and the relay click sounds softer.
 
Last edited:
Back
Top Bottom