sansui 8080 protection---of course

waggs098

Super Member
This receiver goes straight into protection mode. Found same fusible resistor on both channels open. Supply voltage to each should be 54.7 and i read 55.6. Not to far off. Should I replace resistors and see what happens or is there further troubleshooting I should do.
 
This receiver goes straight into protection mode. Found same fusible resistor on both channels open. Supply voltage to each should be 54.7 and i read 55.6. Not to far off. Should I replace resistors and see what happens or is there further troubleshooting I should do.

On the bottom left and right corners of the board there is a fusistor it should be 180 value they go out and increase to like 200.
 
Have you checked dc offset?

There is a sticky here that may help if you are unfamiliar.

My best to you
 
Here is your board the farthest botom outside fusistors are probaly out of value.


images
 
This is my board. I have an 8080 not an 8080db. The resistors third to the inside of the gray caps are the ones that are open.
 

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I had the same problem on my 890 (8080) receiver. After reading the many threads on this topic I made a decision. The fusible resistors and caps really should be updated on these boards and were likely the cause of my problem. Since I'm not experienced like many here, rather than spending time pinpointing with 100% certainty the exact cause of the problem (and since the replacements only cost a few dollars) I just replaced all the fusible resistors and caps. Worked like a charm. Even though I never isolated the exact reason it was in protection, I was pretty sure my approach would work.
 
I had the same problem on my 890 (8080) receiver. After reading the many threads on this topic I made a decision. The fusible resistors and caps really should be updated on these boards and were likely the cause of my problem. Since I'm not experienced like many here, rather than spending time pinpointing with 100% certainty the exact cause of the problem (and since the replacements only cost a few dollars) I just replaced all the fusible resistors and caps. Worked like a charm. Even though I never isolated the exact reason it was in protection, I was pretty sure my approach would work.
Where did you get parts from?
 
Here you are:

Qty - Description - Digi-Key part #

4 - RES 4.7 OHM 1/2W 5% AXIAL - 4.7H-ND
2 - RES 22 OHM 1/2W 5% AXIAL - 22H-ND
2 - RES 10 OHM 1/2W 5% AXIAL - 10H-ND
2 - RES 390 OHM 1/2W 5% AXIAL - 390H-ND
2 - RES 150 OHM 1/2W 5% AXIAL - 150H-ND
2 - CAP ALUM 100UF 100V 20% RADIAL - P10776-ND
2 - CAP ALUM 0.47UF 50V 20% RADIAL - 493-1885-ND
2 - CAP ALUM 100UF 6.3V 20% RADIAL - P1143-ND
 
I checked with digikey and they don't stock a 390 ohm fusible resistor. I would have to buy like 1000 of them. Unless my tech support guy was wrong. Are you resistors replacements fusible or standard resistors.
 
What about a metal film 390 ohm 1% ? You COULD use the carbon… BUT if it blows it will flame out and make a MESS. IF your stuck using a carbon stand it up off the board as high as practical.
 
Will other resistors open like a fusible under the same conditions or does it take more power to open them.
 
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