Ampeg SVT Blueline 1969/70

[Greg Evans]

If you don't know what you are doing, cleaning may do more damage than good. The amp may very well be beyond economical repair. Refurbishments may be possible, but rather expensive. It's also possible the circuit boards disintegrate under a soldering iron. If it can't be rebuilt, there may be some valuable parts that can be salvaged.

Thanks for all the help and info. You’re right, having looked at it I could do more harm than good by cleaning. I will take to someone for an opinion but my sense is it may be one for the scrapyard!

shame but a valuable lesson learned.
Thanks all for the posts!

 

[Bulltrout]

Thanks for all the help and info. You’re right, having looked at it I could do more harm than good by cleaning. I will take to someone for an opinion but my sense is it may be one for the scrapyard!

shame but a valuable lesson learned.
Thanks all for the posts!

Please don’t do that. I’ve done refurbs on about five of these to date. Expensive, but worth it.

 

[Greg Evans]

Please don’t do that. I’ve done refurbs on about five of these to date. Expensive, but worth it.

I will refurb it absolutely if it can be fixed. I bought this when I was 15. I just need to find someone in the UK advise me.

need to source a good uk tech to help me.

 

[Greg Evans]

Please don’t do that. I’ve done refurbs on about five of these to date. Expensive, but worth it.

I have nearly finished the cabs (2 8x10) I bought at the time. Simple wiring and electrics I can do. In depth electronics and power out of my league.

 

[DJ Bebop]

Thanks for the info Wasnex! I am in the cleaning stage, got it all apart and will post som pics today.

Take your servicing to another level!

 

[Greg Evans]

Take your servicing to the another level!

 

[Greg Evans]

Take your servicing to the another level!

there is no way I’m doing that! Lol

 

[DJ Bebop]

there is no way I’m doing that! Lol

Just trying to help!

 

[beans-on-toast]

Your amp can be restored, I’ve seen way worse.

Replace all the rusted washers and bolts. The Switchcraft jack nuts and washers are available.

The transformer bell ends can be cleaned and repainted. Carefully brush off any loose rust on the plates but do not scrape it off. You can leave the rust or it can be sealed and coated with a high voltage dope specifically used for transformers.

With the jacks, pot, switches, and pilot light removed the front panel slides off.

Be careful when moving wires inside the chassis, they can break.

The small tubes are all bad as indicated by the white cloud.

The tube socket contacts should be carefully cleaned with Deoxit D5 and a soft inter-dental brush. Use nothing abrasive. Only use deoxit (sparingly) on the pots and slide switches.

I see a resistor with a 71 date code. The brown paper covered electrolytic caps have a date code. So do the metal cap cans on top of the chaAlso look on other resistors. There are date codes on the pots 137 followed by year and week of year. The hum and balance pots in the back of the chassis are easiest to read.

If your amp is a 71 era, experience tells me that the electrolytic power supply caps in the bottom chassis and the one in the preamp should be replaced.

 

[DJ Bebop]

Latest pics. The beginning of a long journey! All dates point to 1971. Any thoughts or insights greatly appreciated. View attachment 5271806 View attachment 5271808 View attachment 5271809 View attachment 5271810 View attachment 5271811 View attachment 5271812 View attachment 5271813 View attachment 5271814 View attachment 5271815 View attachment 5271816

 

[Ben Clarke]

yeah, get to a tech, as you say you will. I only chime in because I see more advice about how to start on this yourself.

This is not the piece to learn this stuff on.

 

[Sulaco]

I just need to find someone in the UK advise me. need to source a good uk tech to help me.

The Amp Clinic in Manchester. Dickinson Amps (Crystal Palace, London). Essex Amp Repairs.

 

[Greg Evans]

Your amp can be restored, I’ve seen way worse. Ok

Replace all the rusted washers and bolts. The Switchcraft jack nuts and washers are available.

The transformer bell ends can be cleaned and repainted. Carefully brush off any loose rust on the plates but do not scrape it off. You can leave the rust or it can be sealed and coated with a high voltage dope specifically used for transformers.

With the jacks, pot, switches, and pilot light removed the front panel slides off.

Be careful when moving wires inside the chassis, they can break.

The small tubes are all bad as indicated by the white cloud.

The tube socket contacts should be carefully cleaned with Deoxit D5 and a soft inter-dental brush. Use nothing abrasive. Only use deoxit (sparingly) on the pots and slide switches.

I see a resistor with a 71 date code. The brown paper covered electrolytic caps have a date code. So do the metal cap cans on top of the chaAlso look on other resistors. There are date codes on the pots 137 followed by year and week of year. The hum and balance pots in the back of the chassis are easiest to read.

If your amp is a 71 era, experience tells me that the electrolytic power supply caps in the bottom chassis and the one in the preamp should be replaced.

That is super helpful! Thanks.
I am trying to figure out if the input transformer might have a 240 option. I will clean the whole thing as you have described above and see how I go. I am good at taking my time and doin

The Amp Clinic in Manchester. Dickinson Amps (Crystal Palace, London). Essex Amp Repairs.

Thank You!

 

[beans-on-toast]

I am trying to figure out if the input transformer might have a 240 option.

Some transformers could be rewired for 240VAC, others couldn’t. It depends on what’s in your amp. There are third party replacements that can be wired for North American and EU mains. One expensive example:

Power Transformer for Vintage Ampeg SVT/V9 - Product Details

There are external 240 to 120 power converters that will produce a good quality sine wave line voltage for your amp. Another option.

There are TWO power transformers to worry about in the SVT. The main one for high voltage and bias, there is a separate one for the heater voltage, also called FT (filament transformer) on some schematics. Both transformers would have to be rewired for UK power, fuses changed, and the mains plug.

The attached SVT schematic shows how to wire for 240VAC. Note the transformer part numbers and compare them you yours.

 

[beans-on-toast]

Take your servicing to another level!

Soap isn’t a good idea. I’ve seen military radios whose electronics were designed to be hosed off in the field. Even some old tube stuff is reported to be cleaned that way.

 

[Wasnex]

I am trying to figure out if the input transformer might have a 240 option.

I only see two primary wires, Yellow and Black. That means 120V only.

Here is the wiring for 240V

As you see the primary has 8 wires (on the right). This allows you run the windings in either series (240V) or parallel (120V).

Since this amp runs 6550s, there are vintage-style, drop-in replacement PTs available. I would leave this to the tech.


Here are two examples:

Mercury Magnetics

Heyboer

 

[Greg Evans]

Thanks Wasnex. Again most helpful! I have it all stripped and cleaned and it is looking very good inside. Found loads of caps and pots with 71 dates so pretty sure about that. Should be a mid to late one since no exceptions on the dates.
Speaking to a tech tomorrow so hopefully he can fit it in soon.
Thanks again1

 

[Greg Evans]

Some transformers could be rewired for 240VAC, others couldn’t. It depends on what’s in your amp. There are third party replacements that can be wired for North American and EU mains. One expensive example:

Power Transformer for Vintage Ampeg SVT/V9 - Product Details

There are external 240 to 120 power converters that will produce a good quality sine wave line voltage for your amp. Another option.

There are TWO power transformers to worry about in the SVT. The main one for high voltage and bias, there is a separate one for the heater voltage, also called FT (filament transformer) on some schematics. Both transformers would have to be rewired for UK power, fuses changed, and the mains plug.

The attached SVT schematic shows how to wire for 240VAC. Note the transformer part numbers and compare them you yours.

 

[Greg Evans]

Thanks again. You guys have been amazing!

 

[tadawson]

there is no way I’m doing that! Lol

It's a valid technique! A lof of boards get a water wash when manufactured, and there are almost no components that can be damaged by water. When I was servicing amps for clubs, this was a mandatory step to get rid of cigarette smoke residue and bar funk, and they ran a lot cooler when clean as well!

(I doubt I would do it on a point to point wired tube amp though . . . )