I have have a CR 2020 that was not working when I bought it. I've done the service mods. Checked all the transistiors. Each time I power it up the the B+ fuse on one Amp board blows and short out both TR611 and TR613. So far I've shorted 2 of each. Not shure what is causing the shorts. Thanks Avonic, I've read your threads on yammies for the last year. Hope to you and the Audiokarma family can help as I've hit the wall on this repair. Need some direction:scratch2:
Need help with CR2020 blowing B+ amp fuse and out put transistors
- Thread starter ronjon489
- Start date
petehall347
the brandy coffee man
build a dim bulb tester or invest in a variac .. in the meantime check the drivers and the power supply .
I'd previously replaced D605 saw I put it in backward:nono: D606 and 7 were ok. Replaced R601 with a 68ohm 1/2watt. R623 and 624 had a 680ohm resistor instead of the 820ohm resistor called out in the schematic. R625 and 26 are reading 4.7ohms.R628 thru 632 are all ok. I did re-capped the amp boards. Going to build the dim buld tester today. Not sore what watt buld i need to use:scratch2:
Avionic are you there? I changed the diode turned the system on without blowing a fuse. I then hooked up the inputs and the B+ fuse blew and took out both output transistors. Built the dim buld tester but didn't know how what watt to use. Would appreciate any and all help possible. Also noticed the 2.2k resistor gets realy warm.
petehall347
the brandy coffee man
use a 60w or 100w bulb in the dim bulb tester ..it will/should save you wasting output transistors .
ok thanks Pete. the reading on R603 was take in circuit with the system on and the pre input not plugged into the amp board. The second amp boar appears to be ok. Not having any none problems. I've heard the relay click once and that was when the B+ fuse was out of the non working amp board.
I replaced C614. The positive does short to E . checked TR607,608,609 and 610. All were okay. The .47 resistors were at.5. D603 and 604 were ok. Could only check the zener diode at D602 as a normal diode. It check out ok but the leade on the cathode were black. May have overheated. Didn't have a replacement. I'll either go to Rshack or order replacements.