Fisher Space Expander Restoration Checklist (please help me)
Posted: Thu Mar 10, 2011 4:40 pm
Hello,
I've been reading this forum for ages, it's a very valuable source of knowledge, but I only recently registered to this forum, because I aquired an old Spaceexpander really cheap. Needless to say it is trashed, so I will need to put a lot work into it. My skills with the soldering iron are ok, my electrics skills are only medium though, so I could need some help, and I hope together we can help many people who read this to restore the Fisher Spaceex
I thought this would also be an opportunity to have one thread to gather all information needed to restore a Spaceexpander, because I would guess many Spaceexpanders surfacing could be in a state not dissimilar to mine.
Mine is missing the control knob, the reverb tank and the tubes, and also some of the caps are obviously broken
1) get the schematic & parts list
2) replace all the capacitors (now the parts list is really handy when you go shopping for these parts)
If the caps are all original, they are almost 60 years old and pretty much bound to be broken. There is no way of testing a cap with a regular multimeter that I know of, so if you checked everything else, and your Spaceex is still not running, be prepared to replace every single one of them. Besides capacitors are not pricey, and none of them should cost you more than a couple of cents with the exception of the big 4 section elco (the big one sticking out of the case). If you found a replacement it would probably cost between 10 and 20 bucks (I judged this on the price of commonly available Mallory 4 Section Eletrolytics)
Question: has anyone found a direct replacement for the 4 section cap? In the parts list it says 1000V, but theoretically a 350V one would be enough, right?
3) replace tubes if necessary
Luckily the tubes used are still being made and readily available. Specially the 12ax7 is still being produced in large quantities and the cheap ones made by Sovtek (approximately 8 Euros) should do the job.
For the 7247 there is less choice, and they are a little bit more expensive (the ones I found sell at around 20 Euros).
Note: they need to be replaced if they are cracked or show white icing, then they most likely will not work at all, and if, it 's very dangerous to use them. If they glow red when being used they will work, but should be replaced nevertheless.
They should not glow at all when new, and are still ok when they glow in blue color.
4) replace the selenium rectifier (optional)
Selenium rectifiers are to my knowledge archaic, and high risk components, and besides can emit highly toxic gases when they break.
Replacement silicon rectifier should be cheap anyways.
Question: has anyone found a replacement silicon rectifier readily available in Europe?
5) build a control knob (if missing)
according to what I have read the Spaceexpander will not work at all if this thing is missing. It is cheap and easy to build.
You just need a 250k pot (I'm guessing linear), a stereo 6,3mm jack and 3 wires. In the schematic it's also shown, but features an additional on/off switch, which you do not really need I guess.
6) find a reverb tank (if missing)
Luckily accustronics make a direct replacement, which should cost between 20 and 35 Euros, probably depending on the dealer.
The right model should be 4fb2b2c (medium delay) or 4fb3b2c (long delay).
Question: does it come with cinch connectors?
7) convert to European voltage (optional)
Question: has anyone ever done this, and does it make sense? (I would think yes)
according to the schematic the input transformer has an Input of 110V and an output of 290V and 6V.
Is there a direct replacement with an input of 230V?
Ones with 230V input and 230V+6,3V output are commonly available, would these do the job?
How do you run this thing in Europe?
I would be very happy if some more people could add some additional information on the Fisher Spaceexpander and if someone could help me to answer my questions.
greetings, and thanks for this amazing forum
Franz
I've been reading this forum for ages, it's a very valuable source of knowledge, but I only recently registered to this forum, because I aquired an old Spaceexpander really cheap. Needless to say it is trashed, so I will need to put a lot work into it. My skills with the soldering iron are ok, my electrics skills are only medium though, so I could need some help, and I hope together we can help many people who read this to restore the Fisher Spaceex
I thought this would also be an opportunity to have one thread to gather all information needed to restore a Spaceexpander, because I would guess many Spaceexpanders surfacing could be in a state not dissimilar to mine.
Mine is missing the control knob, the reverb tank and the tubes, and also some of the caps are obviously broken
1) get the schematic & parts list
2) replace all the capacitors (now the parts list is really handy when you go shopping for these parts)
If the caps are all original, they are almost 60 years old and pretty much bound to be broken. There is no way of testing a cap with a regular multimeter that I know of, so if you checked everything else, and your Spaceex is still not running, be prepared to replace every single one of them. Besides capacitors are not pricey, and none of them should cost you more than a couple of cents with the exception of the big 4 section elco (the big one sticking out of the case). If you found a replacement it would probably cost between 10 and 20 bucks (I judged this on the price of commonly available Mallory 4 Section Eletrolytics)
Question: has anyone found a direct replacement for the 4 section cap? In the parts list it says 1000V, but theoretically a 350V one would be enough, right?
3) replace tubes if necessary
Luckily the tubes used are still being made and readily available. Specially the 12ax7 is still being produced in large quantities and the cheap ones made by Sovtek (approximately 8 Euros) should do the job.
For the 7247 there is less choice, and they are a little bit more expensive (the ones I found sell at around 20 Euros).
Note: they need to be replaced if they are cracked or show white icing, then they most likely will not work at all, and if, it 's very dangerous to use them. If they glow red when being used they will work, but should be replaced nevertheless.
They should not glow at all when new, and are still ok when they glow in blue color.
4) replace the selenium rectifier (optional)
Selenium rectifiers are to my knowledge archaic, and high risk components, and besides can emit highly toxic gases when they break.
Replacement silicon rectifier should be cheap anyways.
Question: has anyone found a replacement silicon rectifier readily available in Europe?
5) build a control knob (if missing)
according to what I have read the Spaceexpander will not work at all if this thing is missing. It is cheap and easy to build.
You just need a 250k pot (I'm guessing linear), a stereo 6,3mm jack and 3 wires. In the schematic it's also shown, but features an additional on/off switch, which you do not really need I guess.
6) find a reverb tank (if missing)
Luckily accustronics make a direct replacement, which should cost between 20 and 35 Euros, probably depending on the dealer.
The right model should be 4fb2b2c (medium delay) or 4fb3b2c (long delay).
Question: does it come with cinch connectors?
7) convert to European voltage (optional)
Question: has anyone ever done this, and does it make sense? (I would think yes)
according to the schematic the input transformer has an Input of 110V and an output of 290V and 6V.
Is there a direct replacement with an input of 230V?
Ones with 230V input and 230V+6,3V output are commonly available, would these do the job?
How do you run this thing in Europe?
I would be very happy if some more people could add some additional information on the Fisher Spaceexpander and if someone could help me to answer my questions.
greetings, and thanks for this amazing forum
Franz