Fisher RS-1056: No Longer Powering Up

[TechGeek]

Hello!

Went into my Fisher RS-1056 stereo receiver to troubleshoot the damaged meter...

annnnnnnnnnnnnnnnnnd in the process while the unit was powered up(trying to move meter cover to get at actual meter wires) I touched the cover to one of the transistor's heatsinks. Unit shut down. Took cover off. Unit restarted. Touched cover back. Unit shut down. Repeated said process 1 more time(trying to figure out what's going on) and all of a sudden the unit dies and will not restart. Main transformer is good. On the main power board, there is the proper voltage on all pins EXCEPT for pins 3, 4, and 5. Tuner is totally dead. No voltage leading to resistor R01. Ditto for resistors R04 and R05. All fuses are good and the audio transistors are getting power.


I'm stumped. Please help.



Thanks.

Schematic: https://www.badcaps.net/forum/attach...1&d=1484447932

[TechGeek]

Re: Fisher RS-1056: No Longer Powering Up

Hello??

[madan1]

Re: Fisher RS-1056: No Longer Powering Up

can you post some pics of the unit, PSBs, point the parts which touched, the pins that do not read good... etc. .. not everyone is familiar with that particular unit and the schematics need time which not everyone is willing to invest, but the visual aid will work for most people familiar with electrocics

[petehall347]

Re: Fisher RS-1056: No Longer Powering Up

first check all fuses ...if any blown report back before replacing any .
if all fuses test good with a multi-meter carefully get all power supply voltages . report back with a list of readings .
example ..
pin 1 ..12.41v ...
if negative voltage is read then write like this -21.1v
use chassis as ground for black meter probe .

edit ......
ok i bothered to read the first post ..
get ac voltages at pins 1 and 2 .. power supply .

..i bet you shorted a regulated transistor and blew one of those 1 amp fuses or burned a trace on the board . may have also blown a transistor or 2 .

if dont see any ac voltages at pins 1 and 2 . check voltages transformer side of the fuses that feed pins 1 and 2 . ..if no voltages then turn power off and ohm out that winding on transformer .

[TechGeek]

Re: Fisher RS-1056: No Longer Powering Up

ok... popped the fuses. now to find some 1A fuses.

[petehall347]

Re: Fisher RS-1056: No Longer Powering Up

make sure the regulator transistor isnt shorted first ..q1 .
also test the zener diode d05 .
might be ok because if i am right you shorted q1 collector to ground and the fuses caught the main strike .

[TechGeek]

Re: Fisher RS-1056: No Longer Powering Up

I somehow shorted pins 3 and 4 or 4 and 5 together. That must have been what killed the fuses.

[petehall347]

Re: Fisher RS-1056: No Longer Powering Up

deffo test that transistor then .. if it shorted c to e and you power it up the circuits it supplies will see 19v instead of 12 ...

[TechGeek]

Re: Fisher RS-1056: No Longer Powering Up

hmm ok

[petehall347]

Re: Fisher RS-1056: No Longer Powering Up

just trying to save you fuses and more damage ...
hopefully the semiconductors survived . if not just upgrade them .

[Drack]

Re: Fisher RS-1056: No Longer Powering Up

Any news?

[TechGeek]

Re: Fisher RS-1056: No Longer Powering Up

Nope. Fisher makes it dang near impossible to check the diodes on that PSU board.

[vinceroger69]

Re: Fisher RS-1056: No Longer Powering Up

can you use a dim bulb tester in circuit on one of these to protect the fuses and see if theres a short?

[budm]

Re: Fisher RS-1056: No Longer Powering Up

Can we see the pictures of the board we requested?
You can test the diode on that power supply board without removing them for now.