SX737 volume cuts out above 1/4 throttle

madmikesmech

New Member
Hello all, I'm a newbie to this forum. I put my SX737 back into service after a couple of years of basement storage.
The issue is when the volume control knob is turned above 1/4 it kicks the relay out , if I turn it down it again plays. After removing the top case of the receiver I witnessed the relay break contact thru the clear relay cover.
I do at this current time have a 2 channel automotive speaker box connected to it, could this be the problem? Any input would be great
 
Thank you!
Really? I always thought it was not good to operate a stereo with no speakers connected. What would I be looking for? the relay contacts moving?
 
Protect circuit., over current sensing section, 0.22uf capsistors. The dreaded leaky sky blue Sanyo solid aluminum caps that are a guaranteed failure.

awm-025 c1 and c2. 0.22uf 10v
replace with film caps, will never need replacing.

:yikes: both the ecq and dsf caps are coming up scheduled for obsolescence BY THE MANUFACTURER. :dammit:
 
Last edited:
Thank you!
Really? I always thought it was not good to operate a stereo with no speakers connected. What would I be looking for? the relay contacts moving?

it will be fine without speakers ..yes look for the relay contacts . then as mtf says it needs new capacitors anyway .
your car speakers could be too low ohms ..if you have some home speakers you could try them .
 
the capaciters are what is causing the relay to break contact? I sure am glad I stumbled on this forum. you guys are a big help!
I am NOT a radio repairman or very savy in this field! I am a mechanic and I think with help from the forum I may get this problem sorted out! I hope!
Thanks
 
petehall347, I unhooked the speakers and the relat didn't kick out, so I commandeered one of the speakers from the living room the wife has plumbed in to surround sound for the TV.
I feel so stupid! the problem is now non existent!
Thank you guys for the help! you guys and this forumROCK:thmbsp:
 
Arrrgh I missed that "automotive speaker box". They run lower ohms on the car speakers and make it a more current driven system - 4 ohms or less.

That's because unless you are using 12v on the finals, you have to MAKE the higher voltage, pumping the energy "uphill"...
 
In any event, the 737 should be recapped. With it cutting out @ 1/4 volume (on the knob) pushing a 4ohm load, it's showing it's age, and telling you that it needs work.
 
Recapped!? Is that what MTF suggested too? I will look into this update. The 737 is going to be my dedicated garage sound system... now to get my hands on some home speakers! I should get some 8ohm speakers? is this correct?
Thank you ALL FOR THE INSIGHT, & for tolerating this newbie!
 
your car speakers could be less than 4 ohms ..if you have a multimeter check them .
yes use 8 ohm speakers for less stress on the amp .
 
My son brought some extra speakers he had over today. The volume cut out is eliminated. The speakers are far from what the SX737 is worthy of, but they work till I can get something better! The garage has tunes thanks to the generosity of my boy!! Thanks Brenden!
And thank all that responded to my thread! I will be lurking about this forum! lots of good info here
 
I have a 737. Peruse CL or eBay for a pair of Boston Acoustics A40s (I have the Mk.IIs). Add a powered sub (Polk PSW10 is a good match for the A40s), and you will think you have a behemoth.
 
I use my SX-737 with Sansui SP-2500's or Bozak B-300's in Japanese Cabinets(depending on which room), and no need for a sub. In a garage setup, you're gonna need something that moves a lot of air to make up for the size of the garage and all of the "mancave stuff"(junk to most wives) that soaks the sound up. Make sure the new speakers are 8 ohm, and at least 92db efficient. The more efficient the speaker is, the amp will be less strained as it's running at a lower volume setting for a given sound level.

If I use a pair of H.H. Scott S-10's and crank the volume to 5, with the SP-2500's I only have to turn it to 2 due to speaker efficiency for the same volume. The S-10's have an efficiency of about 86-87db, where the SP-200's are 96-98db.
 
It all depends on the speakers. In my case, after the renovation/redecorating, I can only use smaller bookshelfs like the A40s or HPM-4GX. I get great sound from the A40s by themselves. The sub fills in the low end below 68, and really enhances presence in jazz, classical, and 70s rock. I usually cut it out for stuff after the mid-80s.
 
Back
Top Bottom