Pioneer Spec-1

[Randy007]

Hi..I have a Pioneer Spec-1 Power Amp I'm trying to get back in service. My problem is all the B+ and B- voltages are way low measuring 7 volts and 0 volts when I should be reading +48 and -48...also I have no out put voltage from the fuse circuit Bd. to the Power Supply board...also all voltages from the fuse circuit board to all other boards is reading low voltage to 0 voltage, also low voltages from Power supply board to other boards low to 0...I was reading low voltage on the caps on the fuse board, 2 caps are rated to 80v AND 1 is rated to 50V..should I replace these and the 6 diodes on this board...I have voltage coming into the unit, the speaker relays kick on, but nothing else....help

 

[avionic]

This is definitely the wrong place for this post. Need a moderator to move this to the Pioneer forum.

 

[avionic]

A SPEC 1 is an Pre-amplifier last time I looked at one. Do you know how to use a service manual and follow a schematic?

 

[Randy007]

New at this but can read a service manual and schematic, just been check voltages....so far

 

[avionic]

Ohms check fuses FU2 & FU3 with a multimeter out of circuit.

 

[avionic]

New at this but can read a service manual and schematic, just been check voltages....so far

Super. That will make things easier.

 

[avionic]

Excellent.. Moderator move it to the correct forum.

 

[Randy007]

thanks for the response and thanks to the moderator for putting this in the correct forum...do you have any suggestions Avionic....

 

[avionic]

thanks for the response and thanks to the moderator for putting this in the correct forum...do you have any suggestions Avionic....

Ohms check fuses FU2 & FU3 with a multimeter out of circuit.

 

[avionic]

If fuses are still serviceable. Check the DC voltage on the AWR-094 power supply board. Pins 6 & 7. Should be + and - 62vdc. Pin 13 should be 32vdc.

 

[avionic]

http://www.kallhovde.com/pioneer/spec-1smhires.pdf

 

[avionic]

If you can .Post a clear photo of the component side of the AWR power supply board.

 

[Randy007]

Fuses Keep blowing as soon as the amp powers up....

 

[Randy007]

can anyone help, I have fuses 2 and 3 on the fuse board assy. that keep blowing when I turn on the amp..any ideas? Thanks

 

[zebulon1]

You should build a DBT before you continue working on this Spec 1.
Has this Pre amp been worked on?
Whats the story on it?
It's going to take a little bit of skill to sort it out.
Your going to have to remove a few wire wrap posts to isolate the short.
There's a technique to removing the posts without disturbing the wraps.
There is a few shotgun things you could check if you are willing to desolder some components.

 

[Randy007]

You should build a DBT before you continue working on this Spec 1.
Has this Pre amp been worked on?
Whats the story on it?
It's going to take a little bit of skill to sort it out.

Not sure if it has been worked on, came out of a estate sale...very clean unit, but when I got it they said it didn't work, I opened it up and the 2 fuses were blown....I was going to measure the B+ and B- voltages on the power supply when I discovered the fuses..any clues?

 

[zebulon1]

The rectifier diodes on the fuse board. D1 thru D4. Is a shotgun TS (Troubleshooting) approach. They can short out but the best approach is by disconnecting the feeds to the ancillary boards. Finding the board with the short. Transistors will short as well. Your correct. The problem is in the B+ or B- supplies.
Build the Dim Bulb Tester first. This will save fuses.
Your going to need it for this repair. If you want to do it properly.

 

[Randy007]

The rectifier diodes on the fuse board. D1 thru D4. Is a shotgun TS (Troubleshooting) approach. They can short out but the best approach is by disconnecting the feeds to the ancillary boards. Finding the board with the short. Transistors will short as well. Your correct. The problem is in the B+ or B- supplies.
Build the Dim Bulb Tester first. This will save fuses.
Your going to need it for this repair. If you want to do it properly.

I will build the tester tomorrow, should be fairly simple...what size bulb would you suggest...75 or 100w..

 

[zebulon1]

75 watt maybe a 60 watt will work.
The pre doesn't pull a lot of current.
Those fuses are only half an amp (0.5A)

 

[Randy007]

75 watt maybe a 60 watt will work.
The pre doesn't pull a lot of current.
Those fuses are only half an amp (0.5A)

true, I'll build it tomorrow and see if I can find a 1/2 amp fuse, I have 1....hardware stores around here usually don't carry such low amperage fuse