[Jukebox-list] Wurlitzer 2600 Sound update

[Iain Jamieson]

Hi all,

Well, I tried running a new earth from the preamp back to the transormere earth. I also discovered that the squeal noise that comes on after about 5 minutes will go away if the trebble is turned down to a minimum in the B channel. looking at the schematic, the trebble control goes into what is called a P.E.C 112231. A flat package that contains caps and resistors. These are original and was wondering if these could be the problem. However, I discovered something else and was alerted to a burning smell. The 5 watt 310ohm resitors that go to pins V7 - 7, V8 - 9, V9 - 7 and V10 - 9 were cooking themselves. I replaced these and did some voltage measuring on the these Tubes. These are the voltage I got. In Play position V7 - 9, V8 - 7 have 427v DC instead of 380v. In Rest I get 44v DC. On V7 - 1 and 8 read 302V instead of 265v. In rest I get 37v These voltage start higher and stabalize to the above voltage in about 40seconds. Having a look through the schematic, I found a resistor that was a 4k, instead of a 5k, so will replace that tomorrow. We have 240v line voltage here, going through a 117v secondary transformer that is outputting 127vac. Would like to check this first before looking into the squeal issue, but it could all be related? Those power amp tubes get fairly hot. Any advise here would be appreciated. Cheers Iain