700B blew one Right channel 5A supply fuse

[laatsch55]

Gary, after a long , hard think lat night I have decided to send a flawless, mint PL020 board out of Skynyrds Whte Oaked 700. Yes, we will debug that PL14 board eventually, and I really suck at long distance fixing, but we'd wear it and you down at sometime. I have a lot of boards laying around and Ed usually gets em eventually, but not this one. My main concern is the traces on that board. You will have removed and replaced so many components that reliability will be a factor. Going to a friends house roday and hopefully I won't be in any shape to be fixin anything....but we can continue tomorrow. The board will go out Minday Morning....Merry Christmas...

PS. Ot will have the updated caps...

 

[62vauxhall]

That is very considerate and truly helpful but I do not wish you to be out of pocket for the board or postage fees. I still have your address and would be happy to reimburse.

Just to mention, when you address to me, please include that Parcel Express account number 20848 as part of the address line 115 Garfield St. 20848

I was concerned about the board's condition, it's become messy. I really appreciate how much time you've spent helping me. I've come to wonder that since there are other posters besides myself benefiting from your time and knowledge, how do manage to get anything else done? I mean this forum seems like it could be a full time occupation for you and the other contributors too.

Having said that, I hate to say I need another "helpfull hint". The co-axial cables from the volume pots to the board also suffered from repeated board manipulation and their shield connections have broken away. Examining them, I see they are quite stiff probably from the use of foil inside.

Should I shorten the existing cable somewhat and trim the ends for new connections, or use some coaxial cable I have on hand to make new leads? What I have is of smaller diameter than what's on there but has no foil inside. The braided shielding is tightly woven so I don't think there would be an issue from interference. I used it to make a bunch of interconnects once and it seems to be OK. The insulation sheath is marked "VICTOR WIRE MIL TYPE RG174A/U UL1354 30860 RoHS".



I remember my eagerness to fix things increased with impairment. Hope your friend's got nothing for you to fix, so won't ask. Was especially nasty when I was in the floor covering business years ago.

You live in some very nice country. I went on a couple of motorcycle rides in that area, most recently to Sturgis and back in 2010 - stayed a few days just outside of Hill City. We must have gone through or passed by Gillette on I90 coming home because we stopped at Devil's Tower for lunch.

A year or two before, I rode the Going to the Sun Highway with the same people - got to go through the Beartooth Range. Those trips were milestone rides for me and I want to go back soon - love it down there!

 

[Timdalf the Gray]

Well, it remains to be seen if you derive any benefit from my knowledge, jury's still out on that eh?? I'm on Timdalf's computer and after a stint in the garage/shop we have settled in to some serious drinking.......and it's working.....

 

[laatsch55]

Gary, I would just cut it off and start over...

 

[laatsch55]

The low voltage section on the right channel is having problems. Check R4,5,6, 7, 8,9,12. Also check D1,D2,D3 and R51..

 

[62vauxhall]

I'll do that but later today but I'm leaving soon for IA's garage sale to ask Bob Carver to sign my faceplate.

I started looking for the locations of the resistors and diodes you've specified. Not finished yet but I'v noticed so far that some are involved with those "flying connections".

For instance, R1 on the left channel is by itself but R1 left channel has another resistor piggybacked in parallel. Can't identify it's value because it's got 6 bands and I don't know which color band the code starts with.

R51 was harder to find. It's on the schematic but not the board assembly diagram. On both channels, it is wired in series with D1 and D2 which I checked previously (the diodes) and they were OK. Since that was before the latest dim bulb tests, I'll unhook them from R51 to check again along with R51.

I'll identify the other components when I return later from "Seeking Bob" and will post the results.

 

[laatsch55]

OK, D1,D2 will have to be separated this time...and have fun today...

 

[Gepetto]

I'll do that but later today but I'm leaving soon for IA's garage sale to ask Bob Carver to sign my faceplate.

I started looking for the locations of the resistors and diodes you've specified. Not finished yet but I'v noticed so far that some are involved with those "flying connections".

For instance, R1 on the left channel is by itself but R1 left channel has another resistor piggybacked in parallel. Can't identify it's value because it's got 6 bands and I don't know which color band the code starts with.

R51 was harder to find. It's on the schematic but not the board assembly diagram. On both channels, it is wired in series with D1 and D2 which I checked previously (the diodes) and they were OK. Since that was before the latest dim bulb tests, I'll unhook them from R51 to check again along with R51.

I'll identify the other components when I return later from "Seeking Bob" and will post the results.

Bring the amp and a soldering iron and challenge Bob to fix it on the spot!

 

[laatsch55]

Here ya go Gary, the board is worked over and ready to go....

 

[62vauxhall]

OK, D1,D2 will have to be separated this time...and have fun today...

Got home and separated those two diodes from the resistors like before and they test fine and were correctly aligned in that they oppose each other.

In separating them, I was dismayed to see that diodes D1 and D2 were not attached to resistor R51 as they appeared to be after I disconnected and reconnected them several days ago. I guess I did not perform a good enough "tug test" when I last (thought) I soldered them together.

That would probably have been the cause of the trouble?

I disengaged all the resistors you mentioned, checked them and they are all fine.

So now I shall be re-soldering their ends back on the board, hopefully with few or no trace hole casualties.

 

[62vauxhall]

Bring the amp and a soldering iron and challenge Bob to fix it on the spot!

I thought of that but wished to suffer for my mistakes.

I got to Innovative Audio earlier than the start time (but was not the earliest) and killed some time looking over all the gear they were flogging. Bob Carver arrived about an hour later and before he got to the door, I introduced myself and he seemed delighted to sign my faceplate. My intention was for him to sign the inside, which he did, but I thought what good is it if no one could see it? So I got his autograph on the front too.

Since this amp was a little grungy to start with, it might as well stay that way looking battle scarred and have Bob's signature viewable.



He was very friendly and it would have been interesting to have a conversation but he had to participate in the event, sign more autographs and talk with others. What I did do was ask if he knew about this forum or heard of White Oak Audio. He was unaware of either but seemed quite interested in the existence of new boards. I gave him a note with Joe's name re White Oak and Lee Laatsch re Phoenix.

Going there early was very bad for my available space at home because I brought back 2 reel to reels, a pre-amp, a turntable, an 8 track player and some 8 track tapes. Almost a car load for $57.

Anyone have an Akai and and two Teac 7" metal take up reels they want to sell?

 

[62vauxhall]

Here ya go Gary, the board is worked over and ready to go....

That is totally awesome and please tell me how much to send you.

 

[laatsch55]

Gary, first of all thanks for letting Bob know we exist, that's pretty damn cool. Now if he'll just become a member we wouldn't have to speculate about a few things. The board is yours, pay shipping and we're good..

 

[laatsch55]

R51 not having a connection could cause high voltage in the low voltage section. Get that attached again and recheck the Emitters and collectors of Q1-Q3....

 

[62vauxhall]

Gary, first of all thanks for letting Bob know we exist, that's pretty damn cool. Now if he'll just become a member we wouldn't have to speculate about a few things. The board is yours, pay shipping and we're good..

Will hit the bank in the morning and although it's discouraged, I'll mail you a twenty (US bill) tomorrow. I don't think that even buys a 12 pack up here any more but it probably goes further at your end.

 

[laatsch55]

I appreciate the thought....

 

[62vauxhall]

R51 not having a connection could cause high voltage in the low voltage section. Get that attached again and recheck the Emitters and collectors of Q1-Q3....

Did same procedure as before:

Dim bulb (dimmed to orange)
Meter set to DC volts
Black test lead to bus bar and red test lead to Q1 and Q3 Emitters and Collecotrs:

Left Q1
E: -.556 volts DC (minus)
C: +9.0l volts DC

Left Q3
E: +9.78 volts DD
C: +8.9 volts DC

Right Q1:
E: -.564 volts DC (minus)
C: +24.65 volts DC

Right Q3:
E: +25.17 volts DC
C: 00.00 volts DC

 

[laatsch55]

Ok, we go further. Check the collectors and emitters of Q4, Q5....obviously R51 is not the only thing that can cause high voltage there...

 

[62vauxhall]

My attention got diverted by an extended phone call.

Left Q4
E: +9.56 volts DC
C: -61.40 volts DC (minus)

Left Q5
E: -61.5 volts DC (minus)
C: -.740 volts DC (minus)

Right Q4
E: +25.43 volts DC
C: -61.00 volts DC (minus)

Right Q5
E: -61.5 volts DC (minus)
C: -.709 volts CD (minus)

 

[laatsch55]

Shit happens.....Now the base of Q4,Q5....