|
|
|
|
|
#1
03-20-2021, 03:54 PM
|
||||
|
||||
|
Sony SG613
Does anyone still have the Sony instructions on trouble shooting
for shorting SG613 (SG603 etc) ? It would have come out apx mid 70's. AND if you had success did you use the run the set at 18 Volts or another technique ? I dont have one but its just a case of adding useless info to my brain. Also curiosity & boredom ! Its amazing there is next to nothing on the internet on the subject considering how many blew out. We used to refer several a week to the few that would touch one. Comments from the old farts especially appreciated. 73 Zeno  LFOD ! 
|
|
#2
03-20-2021, 05:59 PM
|
||||
|
||||
|
We did tons of those, and success depended on two things: changing all the bad parts at once because leaving one bad part would cause immediate destruction of the others, and use Sony only parts.
When these came in, we'd change the SG613 horiz output, the 2SC867A LV reg, and the damper diode whose number escapes me right now, but I remember the damper was a large metal can type but the Sony replacement was a smaller epoxy diode. If you just change the SG without changing the 867A reg, the SG would fail immediately. If you just changed the 867A without the SG, the 867A would fail immediately. Same with the damper. Change the Holy Trinity of Sony parts using OEM and there shouldn't be a problem. It's been a long time but there might have also been a low value resistor that burned up in the power supply. Been over 30 years since I've last seen one.. It was also important to check the sockets of the output and regulator to make sure they were tight. I used to keep a sharpened awl to make sure they were (helpful with some RCAs like the 132 chassis). Also, go over the whole HV board and make sure there're no bad solder connections, or wayward conductive glue, and look for physically damaged film caps. I don't remember if there was a coupling electrolytic between the horiz osc and the horiz output, but if there is, change that as well. I honestly can't recall any other problem causing those parts to fail. The flybacks were excellent in those. But, do NOT run these on a variac. I'm not sure of the exact chassis but some of the early Sonys would destroy themselves below something like 90VAC or so. John Last edited by JohnCT; 03-29-2021 at 06:16 AM.
|
|
#3
03-28-2021, 08:37 PM
|
|||
|
|||
|
Worked on a lot of these back in the day. Memory is used external variable supply to run horiz osc 19V.It should start at around 5-6 volts.( It was important to run external supply through a diode to prevent damage to supply when sets scan derived 19 V source came up). You could then bring the set up on a variac while monitoring the collector of the SD613 with a scope and the 130 V B+. I remember there is at least one electrolytic coupling cap between the oscillator IC and the H driver that would change value and distort the drive and cause repeat SG613 failures. Other issues were bad solder dips , good practice to re-solder all SG613 collector circuit components. Never had a bad flyback or tripler in any of those. Those 114 degree sets had fantastic pictures if CRT was strong really outshined all the competition at that time. Actually enjoyed working on them because you had something really nice once repaired and set up.
73- Paul
|
|
#4
02-05-2022, 07:45 PM
|
|||
|
|||
|
Can you still find SG613's The ECG sub did not hold up well
Its been since 1988 since I've worked on one of those. If memory serves their was a wonky diode in the startup supply that would leak injecting its pulse onto the gate of the SG613. The pulse width was to wide and poof! Given the age of the set replacing diodes and series pass regulator xister and small electrolytics in the LV power supply should make it a happy set.
|
 |
|
|
Hybrid Mode
