QRX-7500A Capacitors

[jrobertson]

I have a QRX-7500A that has some caps breaking down. It was bought new in 1975. I am replacing the caps on the power conditioner board 1515 and notice that the ones that are mounted directly on the circuit card rather than elevated have a sealer/glue on them. Does anyone know what this is and do I need to use something on the new ones. Is it for vibration? I wouldn't think it would be a heat sink material, they shouldn't get that hot. Maybe a locktite material? Any suggestions would be appreciated. Thank You! John R.

 

[larryderouin]

The glue was put on the caps to hold them on when it was wave soldered by machine. The board was upside down, hence the glue. And that's all it was used for. Sansui's glue had a tendency to be corrosive to parts, so when you get the old caps off, REMOVE the GLUE, and clean the board locally with Q-tips, alcohol.

You don't need the glue with the replacement caps.

 

[scottrt]

The older and browner the glue, the easier it comes off. I use 91% Iso Alcohol and a small 5/32 wide worn out (no sharp edges left) screwdriver to peel the glue back. COming in at a shallow angle removes the glue without harming the silk-screening.

Look for corroded leads on any components that are in contact with the glue. We have all seen resistors and diodes that are no longer 'in cct' because a lead was corroded thru.

Scott T.

 

[jrobertson]

Glue on caps

Thank You for the information on the caps. This has been a good receiver/amp and hopefully I will get a few more years out of it!

 

[budgetaudio6]

yes its a nice reciever, i enjoy mine for vynil listening and the radio. Got it with all papers attached. Wonder if i should send in the warrenty info?:scratch2:

 

[jrobertson]

QRX-7500A Replacement Caps

I replaced All the Caps on the power Conditioner Board and found two bad Transistors. After that the QRX-7500 is working Great! Love It!!

 

[Stene]

The glue was put on the caps to hold them on when it was wave soldered by machine.

Are you sure they used wave soldering during that time period. Most of the models were "hand made"