BIG problems

[Michael F]

Damn I wish my care package had gone thru. It had all the caps you needed for both channels, C3, C11, C6, C15, C16. All Nichicon KZ (Muse) series. In the factory boards, you can drill out the component thru holes. I use a cutting torch cleaning set which is a pin vise with very small drill bits. Those caps I'm not familiar with. Should get you up and running though. Got a cap checker on your meter??

That would have taken care of all the electrolytics, with nice caps too. Were those values altered as well? But if one were to change only one cap it would be C6.
I`ll put the new ones in along with the diodes. While not Muse, they must be better than whats in there now I suppose.

 

[laatsch55]

Yeah, if you change anything, change C6.

 

[fitz43]

Damn I wish my care package had gone thru. It had all the caps you needed for both channels, C3, C11, C6, C15, C16. All Nichicon KZ (Muse) series. In the factory boards, you can drill out the component thru holes. I use a cutting torch cleaning set which is a pin vise with very small drill bits. Those caps I'm not familiar with. Should get you up and running though. Got a cap checker on your meter??

Where did it end up?

 

[Michael F]

Where did it end up?

Devils Triangle

 

[Michael F]

Been busy.

Star ground scheme
DONE

C6/diode mod
DONE

Q`s 1,2,3,4,5,6,7,8,9,10 replacement
DONE

I`ll start mounting the drivers and outputs tomorrow.
I bought me a nice Xcelite 12" long nutdriver with a magnetic 1/4 socket to remove the 48 TO-3 screws, made things sooo much easier. Would using a telescopic magnet be a good idea to re-insert the semi`s or can the magnetic field potentially damage the junctions?
What method do you guys use?

 

[laatsch55]

I use a mag head 1/4" bit driver. Find em by the dozen at the local hardware store. Gewt the thin walled one. Might have to grind some off the sidewall of the bit anyway.

Drivers FIRST,, bring it up THEN THE next row of outputs------One row at a time Lad.

 

[laatsch55]

Get some heatsinks on Q7,Q10 also.../

 

[Michael F]

I use a mag head 1/4" bit driver. Find em by the dozen at the local hardware store. Gewt the thin walled one. Might have to grind some off the sidewall of the bit anyway.

Drivers FIRST,, bring it up THEN THE next row of outputs------One row at a time Lad.

Hmmm... Change of plan then. I wanted to mount the TO-3s in order to replace the emitter resistors, much easier to do when sockets are in the right position.
I don't understand what you mean by "THEN THE next row of outputs"

 

[Gepetto]

Star ground scheme
DONE

C6/diode mod
DONE

Q`s 1,2,3,4,5,6,7,8,9,10 replacement
DONE

I`ll start mounting the drivers and outputs tomorrow.
I bought me a nice Xcelite 12" long nutdriver with a magnetic 1/4 socket to remove the 48 TO-3 screws, made things sooo much easier. Would using a telescopic magnet be a good idea to re-insert the semi`s or can the magnetic field potentially damage the junctions?
What method do you guys use?

Hi Mike
I don't think you have the star point ground quite right yet. I think I still see the 220K resistors running from the normal-direct switch to chassis ground. If my reading of your photo is correct then this has to be fixed. I sent you a photo earlier of the recommended wiring scheme.

 

[laatsch55]

From the bottom of the chassis up there is one row of drivers and 5 rows of outputs going horizontally accross the back. Vertical rows, one at a time.

 

[laatsch55]

Mike----is C3 on that particular board 220uf@ 50 volt?? or 100 volt??

 

[laatsch55]

Don't need the outputs in to hold the sockets in. Run the holddown screws in alone to hold em.

 

[Michael F]

Hi Mike
I don't think you have the star point ground quite right yet. I think I still see the 220K resistors running from the normal-direct switch to chassis ground. If my reading of your photo is correct then this has to be fixed. I sent you a photo earlier of the recommended wiring scheme.

Nice catch Joe!

 

[Michael F]

Mike----is C3 on that particular board 220uf@ 50 volt?? or 100 volt??

47uf@100v

 

[laatsch55]

OK, at times they have ranged from 33uf to 220 uf.

So, have you fed some AC to it yet??

 

[Michael F]

So, have you fed some AC to it yet??

Funny guy
I just finished doing Left channel emitter resistors, Right channel on Friday.
Progress is slow due to the extreme precautions that I`m taking, failure is not an option.

So then, should I only install the drivers for initial testing?

 

[laatsch55]

Correct....

 

[Michael F]

Correct....

What wattage would be ideal for the DBT,considering the driver board is un fused.
If it passes bulb test, what should I be looking for?

 

[laatsch55]

100 watt is fine, the bulb will start out very bright AND IMMEDIATELY start to dim. That's what you are looking for, if it starts to dim, adjust bias as soon as you can. Have your meter hooked up to the bias points and ready to go.

 

[Michael F]

All right then. I`m pretty sure the driver and output transistors Lee is sending over are worthy of your confidence

So if I understand the initial power up process correctly, with B+/- fuses replaced with 200R resistors and a 40w bulb, working one channel at a time:

Turn amp on with driver board alone. If good, proceed to installing drivers. If good, move on to measuring DC offset and adjusting bias according to service manual. If good, install output transistors, cross fingers, say a prayer to the Audio Gods and turn amp on.

Does that sound about right?

I`ll do the initial test with the drivers in position as per Lee`s suggestion . I managed to borrow a variac from a place I work at for the weekend.
Is the combination of variac, DBT and 200R "rail fuses over-cautious?