Gretsch Amplifiier Restoration Help

[Thurgood]

I have a Gretsch 6159 Dual Bass amp that is calling for attention. Poor thing survived a flood in the early seventies with some cosmetic damage, years in a garage with high humidity (mississippi) and abuse from a teenage guitar player (me). Now I am old, it is older. I did fire this thing up about 10 years ago and it operated. The amp sounded great as I remember but it did hum like crazy. I desire to return it to full operation. I am handy with electronics and have built a couple of tube amp kits (5e3, 5f4 etc.) So I ask you where do you begin?

I do know it needs a 3 prong (proper ground) power cable. You should see the "rig" someone in the past wired up.
I see that it has replacement caps inserted sometime in the 60's or 70's (I have had the thing since 1982).

Rusty chassis
Paint coming off
Scratchy pots, missing knobs.
No tubes (pre-amp etc.) I scavenged those many moons ago.....RCA, one old Mullard that I still use today.

I am not even going to mention the cabinet as that is a whole other situation.

What is the sensible method a professional would go about restoring this amp. I am confident I can do most of the elements, nonetheless I seek guidance as to the order and various techniques. Thank you in advance.

WRS.

[Gtr_tech]

The filter caps need replacement if it hums badly. A 3 wire grounded pwr cable is a must. You *may* have leaky coupling caps in the signal path....depends on what they were using that day. I restored an old Supro recently from the same time period and they used good quality film caps in that one so I left 'em all in after checking a couple. Cathode bypass cap in the output section should be replaced as well. Mount it away from the resistor...it gets pretty warm and will bake the cap if placed too close to it.....

Other than that, check all resistors and replace any that are out of tolerance. It prob'ly has 10% resistors so they won't read right on value most of the time.

[Gtr_tech]

Oh....and some 470r 1-2w resistors on the screens is a good idea. Old mfgr tubes could handle the abuse, but todays "polished turds" really don't like the screens pummeled. Some 1.5k grid stoppers on the control grids would be a wise move too, just for stability with new tubes.

[Gtr_tech]

http://i12.photobucket.com/albums/a2...gretch6159.gif

Just for reference, this is what you have.

[Thurgood]

Thank you, thank you thank you....I will save this thread and post as updated. GR thanks. I looked at the schematic and it looks familiar but my golly the layout in the amp looks like a cluster mess. This amp/chassis is dirty , and gives the appearance of poor wiring and layout. Rat's nest.

In your opinion/advice where to start? Do I remove board, tran's etc and clean the chassis? or move forward checking voltages and just getting the thing running? Why fix "what ain't broke"? comments please.

[Jazz P Bass]

If it was mine, I would ditch the 6973 tubes.
They are too hard to come by & cost way too much.
From what I have read, the reissue EH 6973's suck ass.
Rewire the socket for 6BQ5 tubes.

[Gtr_tech]

It uses 6L6s, not 6973s.

[Jazz P Bass]

You know, I just got finished with a 6158.
It looked, cabinet wise, like a 6151.
That was the only resemblance.
It had (2) 6973's in it.
Cathode bias.
A 5Y3GT rectifier, also.
The strange part was the 'standby' switch.
It connected the two output tube grids together at standby.
What a sweet sounding 1964 amp.
It broke up wonderfully.

[Gtr_tech]

Strange then. Were they recycling model numbers? I know the 6973 amp....I had one as my first amp. 1-12, 5y3, trem.

[Thurgood]

Thanks for the schemo. Yes this amp has the 6l6 -12ax7 config.On side note I pulled the original tubes out of this thing years ago....gold mine!! Rca 6l6's 2 westinghouse 12ax7's and a non-spec RCA 12at7. I still have and use'em as subs in my Emery Superbaby. I am going to give it a dusting, do a visual, replace power cable then check resisitor values/continuity check where applicable. Would it be OK to then do basic voltage checks? THis amp did work but like I said it hummed like mad. I really want to get it working and back in the original 2x12 cab. Not in a big rush as I have plenty of time to work on it.

[Gtr_tech]

You may as well replace *all* the e-lytic caps before even trying to t-shoot a hum problem. Fresh caps....then go from there.

[Thurgood]

You may as well replace *all* the e-lytic caps before even trying to t-shoot a hum problem. Fresh caps....then go from there.

I was afraid that would be recc. first. THis amp is layed out with terminla strips (11) and would'n't ya know most of the caps are buried on the bottom rows of each strip. Patience will be in order. Thanks.