No power power supply not coming after replacing bad STR

Hello Terence, for what you are saying, that you have 12.6 volts in leg 4 (Supply) of STR G6551, according to the data sheet, it is low, it starts working from 14.4 volts, typical 16 volts and maximum 17, 6 volts
you would have to check the values of the power resistances of leg 4, also the capacitors and the optocoupler
I send you link to the JVC THS 55 DVD service manual and the STR G6551 data sheet
I hope you manage to make your JVC THS 55 DVD work
Greetings Franco Dosil

Hola Terence, por lo que comentas, que tienes 12,6 volts en la pata 4 (Supply) del STR G6551, seg?n la hoja de datos, es bajo, arranca a trabajar desde los 14,4 volts, t?pico 16 volts y m?ximo 17,6 volts
Tendr?as que revisar los valores de las resistencias de alimentaci?n de la pata 4, tambi?n los capacitores y el opto acoplador
Te env?o link del manual de servicio del JVC THS 55 DVD y la hoja de datos del STR G6551
Espero que logres hacer funcionar a tu JVC THS 55 DVD
Saludos Franco Dosil

https://data2.manualslib.com/pdf6/131/13048/1304751-jvc/ths55.pdf?db8ebd3eff0aa0d74663cb4bd3a1ca7f&take=binary

https://www.promelec.ru/pdf/STRG6651.pdf

Replace that STR. Before replacing, check all the related component/s at the SMPS section [HOT] side. any one damaged component will make the replaced STR to fail. If you wish to get some details; check the site linked here. Pull up older posts.
http://electronicshelponline.blogspot.com/
SMPS Circuit diagrams [STRW6754] of many popular brand TVs and other devices are given.
Search the site by type in the "BRAND NAME" or the STR number; of your device; (Exclude the model number), in the "Search box at the top right of the display window of the Homepage" to get gathered related posts.

First of all; it is DANGEROUS to fix a power supply if you don't know what you are doing. Thus; don't even think about to open power supply tower, if you are not qualified enough.

If you are a qualified person, you can go on with below steps by taking risk on your own.

You must discharge biggest capacitors in order to avoid any fatal electrical shock. Even it is disconnected from electricity plug, power supply may keep high voltage in it for long time. Once you discharge big capacitors; you may diassemble power supply tower. At your question you mentioned about burned power supply which makes it a little bit easier. (I assume you discharged big capacitors) Once you open psu tower; do visual inspection on each capacitor. If there is a burned area start with it. Remove blowed capacitors and replace them with same valued new capacitors. If you can't see the values on blowed capacitors; you need to find board diagram of your psu. Otherwise you can't find suitable one to replace. Besides; check form of other capacitors. If there is a change on any capacitor's form, replace them too. The best way to find out dead capacitors is using capacitor testers. If problem caused by another type item; its not easy to find it as finding bad capacitors.

The STR or voltage regulator is probably bad. If you are not familiar with soldering and using a multi meter for troubleshooting then I suggest buying another power supply they are not too expensive. Try e-bay. Good luck

There are internal fuses that you can check. This model was notoriously bad for amp problems. These amps would burn up a lot of components when they go out.

check for a bad regulator in the power supply section, if it is getting hot after a few second then it needs replacement.

The power supply is bad. Check for open fuses. If fuses are good, then the voltage regulator in the power supply may have damaged.

Try replacing the big Electrolytic Capacitors in the power supply section. When they go the let the 50/60HZ hum into the audio from the mains supply.

i went to sony's webite and called direct and got a power supply for just under 200 dollars to my door better than paying 1500 for a new one i over loaded mine and plug to may things in the back of it but the part is available

Serious problem either in the power supply or output stages of receiver.