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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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22nd Oct 2014, 2:23 pm | #21 |
Octode
Join Date: Dec 2003
Location: Leeds, West Yorkshire, UK.
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Re: Saalburg 5380 Initiation
Hi Majorwest. My Saalburg 5170C radio looks similar to your 5380C radio, but the dial seems to be a different colour.
With reference to the tuning capacitor jamming, mine was in that state due to the ferrite aerial rod and coils falling off the gantry, due to the rubber bands holding the rod to the gantry perishing with age. I was lucky to get a replacement gang from someone that used to supply parts for vintage radios in Germany. Did the tuning gang in your radio suffer with a loose fallen rod? Cheers Mike |
22nd Oct 2014, 4:34 pm | #22 | |
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Re: Saalburg 5380 Initiation
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To the rest of you, some update on the set: Yesterday I tested the reservoir cap with the power off. It had been off for a few hours and I got a voltage of at least 100 volts across the output. Thus, I'm taking care to beware what I touch when unplugged! What threw me a bit with this set is what I know about valves is based on traditional vintage British layout. This one has wax coated transformer windings and the smoothing cap is like a can. Then you have the PCB. I have vintage transistor sets that don't even have a neat PCB. I now plan to study the diagram later. I have a very strong feeling the 1 K resistor that is located on the output transformer is missing its connection. After all, nobody is going to insert a resistor with an end terminal that doesn't even go to chassis and serves no purpose. I measured this resistor today. On setting my cheap multimeter to 2000, I got an ohm reading of 960 max. There is also another resistor on the output transformer but this is properly connected. Actually I had been feeling a bit discouraged the last couple of days but I think I just need to go slowly and bear in mind this isn't the easiest of sets for a beginner. By "beginner" I mean I lack experience getting my hands dirty on an actual radio. Let us hope the diagram wlll help me restore audio and then I can draw a diagram of the mian wire connections in case something else breaks off. |
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22nd Oct 2014, 4:50 pm | #23 | |
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Re: Saalburg 5380 Initiation
Quote:
For now the absolute priority is to restore sound. I started yesterday from the rectifier valve to try and get a basic idea of the power stage. I don't yet know the pins but I could see two identical wires connected to pins that I figured had to be the anodes (from the transformer). One pin connected to the reservoir can lug so I assumed that is the cathode. I tested the reservoir cap and got a hefty voltage reading. I dislike doing big voltage tests with a cheap digital meter and am thinking of a Variac - not sure how much they cost. All that needs to be done is to trace the 1 k resistor connection on the output transformer. I could also test HT across the floating red wire when I find a safe reference to do that from. |
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22nd Oct 2014, 4:55 pm | #24 | |
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Re: Saalburg 5380 Initiation
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Radio Veronica is indeed on the dial. Myself, when I was a kid, it was usually Radio Luxembourg I tuned into. |
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23rd Oct 2014, 4:55 pm | #25 |
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Re: Saalburg 5380 Initiation
Update: Radio sound now back on. It turned out the fault was indeed HT feed to the 1K resistor R35 rated at 2 watts. Adjacent to the resistor is actually C59 4700 pf (shown on the schematic). This connects to the output transformer. The other side of the transformer goes to R35.
The tricky part was trying to find capacitors C60 and C61. No sign of them at all but you can see the output transformer finally gets HT from C61. I finally decided to switch the set on and let the valves warm up. Then it was matter of touching the suspect wire to R35 and sound then resumed. The plan is now to make a diagram in case other connections break off at some point. Hopefully I can now move on to the variable capacitor shaft. |
23rd Oct 2014, 6:38 pm | #26 |
Octode
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Location: St Ives, Cambridgeshire, UK.
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Re: Saalburg 5380 Initiation
C60 and 61 should be the largest capacitor(s) in the set so shouldn't be too hard to spot. I've not seen the set but a large silver 50 +50 uF can near to the transformer??
Good to read you've got sound. Andrew
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24th Oct 2014, 3:54 pm | #27 |
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Re: Saalburg 5380 Initiation
Where I struggled a bit was the red wire couldn't be traced to its source directly. True, it emerges from the smoothing capacitor but no sign of that so far as a number is concerned. There is a large metallic can right next to the rectifier tube and input transformer so I concluded the caps were inside the can. You have reels of wires emerging from the can and rectifier but they disappear in casing. In the end, it seemed logical if the HT to the resistor was a high value, it had to be from the can. So, I just hoped for the best and touched the wire to the resistor lug. That did it.
Now, I'm pondering where to go from here. Do I have the know-how to fix that large tuning condenser and do I risk making things worse? Have to chew it over. I did find the waveband coils but what is odd is that on changing push buttons nothing happens at all. Say you have a station on and change bands. The station will just keep going. It's not as if the band changes to just crackles or hum. So, I wonder if both the contact switches need fixing as well as the condenser. At this stage I have no idea as this is more or less my first set to work on and it's not beginner friendly. Again, thanks to all for the advice offered to date. Last edited by AC/HL; 24th Oct 2014 at 5:30 pm. Reason: Pointless repetition of the preceeding post removed |
24th Oct 2014, 7:57 pm | #28 |
Octode
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Re: Saalburg 5380 Initiation
The large can does contain C60 and C61 and they are the smoothing capacitors
Regarding your lack of bands, check around the contacts on the piano key switchboard, they will need careful cleaning but also look for burnt sections on the Paxolin board. I worked on a Blaupunkt set a while ago that would not switch bands. This was caused by the HT arcing between two closely placed contacts, due to a build up of dirt I imagine. Once I repaired this, the set worked perfectly. Obviously this may not be the problem in your set at all but is an example of a fault you may wish to consider. Andrew
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27th Oct 2014, 5:53 pm | #29 |
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Re: Saalburg 5380 Initiation
Sort of good news. I managed to partly fix the Variable tuning condenser. This was done by lubricating just the shaft with WD40 and re-aligning the cog. At first, the condenser wouldn't budge but eventually I got it revolving and worked it around. It will only rotate so far and then seems to stop as air gaps close. I found out WD40 sprayed on a condenser can upset the capacitance so I was careful not to get it everywhere, just the shaft.
I did find something strange around the PCB inside. Like an oily, sticky staining. At some point, I suspect the radio started playing up and someone has had a go fixing the tuning and finally loosened the grub screws on the condenser. Anyway, if I can get the contacts on the wavebands working, maybe I'll have success. By the way, I'd hate to take the tuning chord mechanism apart. It seems as bad as the notorious Phillips system. |
28th Oct 2014, 4:45 pm | #30 | |
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Re: Saalburg 5380 Initiation
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29th Oct 2014, 5:30 pm | #31 |
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Re: Saalburg 5380 Initiation
UPDATE: O.K., so at a crossroads now. After a very careful clean of the pushbuttons and board around the windings, I'm now able to see at least one of the aerial band coils is off circuit. I suspect it may also be worse than that, overall. The waveband mechanism on this set involves various bobbins with tiny coils and the disconnected end I can see is a tiny thread (difficult to see).
There are various alternatives ahead. I could either leave it as it is and bear in mind this is a pretty advanced radio for a beginner and also made much more difficult by the fact the workshop manual is in German. Alternatively, I could go in for the long haul and bravely dismantle what's needed to gain access and then work on the windings. I'm wondering also if it's typical for coils to be so small as these are. The main ferrite rod is a really big coil but the other pushbutton coils are miniscule. I cleaned all the contact points I could find but my feeling is there has been some damage at a point and the set has been used for some time on only one band. |
7th Nov 2014, 4:32 pm | #32 |
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Re: Saalburg 5380 Initiation
Further update: This project is on hold for a while. I'm pretty sure the very fine coils are open circuit so the set has been operating only on FM. I did do some further investigation and it's a really state-of-the-art set with a triple diode triode included. Even pure German valves to be found.
Compared to other radios I've recently encountered, it's much more advanced. May need restringing and some delicate coil work and will try later when I learn a bit more. |