Need help to repair two phase 400 amps

[LarryD]

I am going to change out the output screws with Allen heads and the cap screws the same. Maybe even the inspection plates as well.

I think it was a simple break but I am not sure. It has been a long time and it didn't blow on the test speaker.

 

[LarryD]

But it was a 8 amp fuse! there are 5's in it now

 

[LarryD]

I think I am going to have to kick for the protection circuit. the rca's suck! so do the speaker connectors!

 

[laatsch55]

I am going to change out the output screws with Allen heads and the cap screws the same. Maybe even the inspection plates as well.

I think it was a simple break but I am not sure. It has been a long time and it didn't blow on the test speaker.

I've never seen an allen head sheet metal screw in a #6. While the outputs are out, with your meter on 200 ohms, check each resistor on the backwall. there are 4 emitter resistors , 4 driver resistors and 4 bias resistors...

 

[LarryD]

Ok Lee, If it is ok with you can we continue tomorrow? I got 6 hours sleep in the last two dats and drove over 600 miles. I am beat.

 

[LarryD]

yes they make them, When I pick them up I will get extra if you would like some? I had to turn the socket down on my leath to fit in between the transistor and bolt.

 

[LarryD]

Ok Lee, I will do my best and check them twice! Thank you very much for your time tonight and I hope to see ya tomorrow !

 

[laatsch55]

Yeah, time for me to hit the rack too. Larry, I dson't need any output hold down screws. I rarely replace any on a stock unit, and the White Oak backplanes require #6-32 machine screws....

 

[laatsch55]

yes they make them, When I pick them up I will get extra if you would like some? I had to turn the socket down on my leath to fit in between the transistor and bolt.

I had to turn down a long nut driver to do the same thing.

 

[LarryD]

They are .125 longer but we can grind tips or use a extra washer.

I had to turn down a long nut driver to do the same thing.

I had a quick look at the resistors. Because I am such a rookie I have a ton to learn. First I will have to find out what they look like in the amp and then their value.
Lee, What kinda sucks is that I need to be working on clients motorcycles to have a little income. I have at the moment exactly zero bucks! And very little coming until I finish
up the bikes. I have traded one of my amps for some speakers and some money. I want to get the amp repaired as soon as I can. But I know these things can't be rushed. So I
am asking if you could hang in there with me as I will be in and out, I have no choice. I have to be able to eat. It is that bad right now. Waiting for a small pension that should start soon. With that being said, Do I need to remove solder from one leg on the resistors to check them and can you give me a hit as to what colors they are? I see four small ones connected to the bus on each bank at the bottom (green and yellow strips). And I also see four that are a little larger with a yellow and silver strips. I am guessing but would these be 8 of the 10 you mentioned ? P.S. when my pension starts I will purchase all allens for the 5,900 caps because those flat heads just do not cut it ! and the output transistors and covers and a long tee handle for you, Perry for helping. It would be the least I could do. Thanks

 

[laatsch55]

My bad, there are 4 emitter tesistors, 1 bias resistor, and one driver resistor per vertical row. A 150 ohm on the driver, a ten ohm in the middle of the row and a point 22 (?) Emitter resistor on each one.

 

[laatsch55]

I'll be around all day if I don't get called out to the field...

 

[laatsch55]

Larry, if you modify a post I'm not alerted to a new post so I usually don't notice them. I only noticed your recent post modification because I was reviewing your last post. I do not need anything in the way of new tools or parts. I have everything I need and a lot that I dont. Don't feel obligated to send anything in return for help. I have mostly everything my little heart desires. I help because people have helped me in the past. It's that simple....

 

[laatsch55]

Edit=Modify......same thing...

 

[LarryD]

Edit=Modify......same thing...

Ok Lee, Thanks. And I will stop modifying the posts. So I am feeling a little in the dark with the resistors. Do I have to remove one leg to check them. And am I looking for current in one direction only or just continuity? Sorry for the stupid questions.

 

[LarryD]

Ok transistors , got it. Another question of about a thousand I have for you. I have the 5,900 caps out and they measure different just sitting. Is that normal or does one have a leak of some sort? The difference is about 25%.

 

[laatsch55]

You do not need to remove them. We are checking the present value to see if they've drifted....

 

[laatsch55]

And post a pic of the backwall so I have some reference...

 

[laatsch55]

Ok transistors , got it. Another question of about a thousand I have for you. I have the 5,900 caps out and they measure different just sitting. Is that normal or does one have a leak of some sort? The difference is about 25%.

What are you measuring?. Tesistsnce? Volts?

 

[LarryD]

What are you measuring?. Tesistsnce? Volts?

Yes volts, one measures 56 the other 29. Not sure I am doing it correctly but that seems to be a big difference? And what about the resistors? What am I looking for direction or continuity?