Hi, R66, a 2K7 wirewound component which is the main dropper for the VR150/30Â has burnt out in my 680X.. The components list does not give the power rating...
2961
rkavampsev@...
merlinrail
Jun 14, 2012 8:44 am
Hi JIm Measure the set ht and you know the vr150/30 draws 30 milliamp max at 150 v so set ht, minus 150 v times 30 milliamp equals wattage of dropping ...
2962
Jim Jobe
jimjobe1
Jun 14, 2012 10:09 pm
Hi Roy, Many thanks for getting back to me - so that should give 4.5W (assuming 300V HT). I think the 2 valves obtaining their HT from the VR150 take about...
2963
rkavampsev@...
merlinrail
Jun 14, 2012 10:42 pm
Hi Jim. Your nearly right if the two valves that have the stabalised ht voltage going to them draw 10ma each being 20 ma in total then to maintain the ...
2964
Graham Adcock
coolcaringer
Jun 14, 2012 10:43 pm
Jim - the 4.5W you've calculated is correct for a 300V HT (300 - 150) x 30mA = 4.5W. This runs the 150V regulator at its maximum current. However, the 20mA...
2965
Jim Jobe
jimjobe1
Jun 14, 2012 10:48 pm
Ah, of course! I should have remembered that. Zeners are the same are they not? I think I'll initially just solder one end of the resistor in circuit and...
2966
Jim Jobe
jimjobe1
Jun 14, 2012 10:50 pm
Cheers Graham. I only placed this query initially because the original resistor looks like a 12W item - one of those green glossy vitreous W...... types, 73, ...
2967
Graham Adcock
coolcaringer
Jun 14, 2012 10:53 pm
As you say Jim, similar to Zeners. The green resistors are probably Welwyn - vitreous. Good bits of kit in my opinion. Probably got one if you're stuck... ...
2968
Jim Jobe
jimjobe1
Jun 15, 2012 11:41 am
Welwyn , that's it, I couldn't remember last night (I'd just got in from a hairy day followed by a 200 mile drive!) I've got a big tin of Welwyn resistors but...
2969
Jim Jobe
jimjobe1
Jun 15, 2012 1:03 pm
I've connected up the new resistor and it's drawing 47mA which makes just under 6W dissipation. I was surprised at how hot it runs though (having burnt my...
2970
rkavampsev@...
merlinrail
Jun 15, 2012 1:13 pm
Hi Jim Something wrong here If its drawing 47 ma then the stabaliser valve isnt within its working capacity Pull out the two valves that the stabaliser is for...
2971
Jim Jobe
jimjobe1
Jun 15, 2012 3:14 pm
Is 47mA not a bit high, considering 40mA is the absolute max for the VR150? I know that less than this actually flows through it under normal conditions but...
2972
Jim Jobe
jimjobe1
Jun 15, 2012 3:54 pm
I've already though of that Roy but I think it's the 275V that is causing the high current, but that seems to be within spec as Eddystone quote 260V +-5% in...
2973
Jim Jobe
jimjobe1
Jun 15, 2012 3:57 pm
PS; Your attachment was blocked by Yahoo.It seems the group isn't set up to receive attachments. Can you send it direct to me please? Jim ...
2974
BenG4BXD
militaryoper...
Jun 15, 2012 4:35 pm
Some valve(s) presumably increase their Ia with increasing signal input. ... if not all?...
2975
Jim Jobe
jimjobe1
Jun 15, 2012 5:27 pm
That's right Ben. It's interesting to see what a big effect that has on the HT voltage, jim ________________________________ From: BenG4BXD...
2976
Jim Jobe
jimjobe1
Jun 15, 2012 6:31 pm
The plot thickens! I've just measured the HT voltage again (DMM) and, with the Archers tuned in on R4 MW, I'm getting 300V at the rectifier side of the choke...
2977
rkavampsev@...
merlinrail
Jun 15, 2012 6:40 pm
Jim Measure the AC going into the set off the mains My mains here is 256 volts instead of 230-240 which its supposed to be cheers roy Gm4VKI...
2978
Jim Jobe
jimjobe1
Jun 15, 2012 7:00 pm
That's an idea Roy, I'll try that in a mo, Jim ________________________________ From: "rkavampsev@..." <rkavampsev@...> To:...
2979
Jim Jobe
jimjobe1
Jun 15, 2012 10:33 pm
It's 244V Roy, not enough I'm afraid! Jim ________________________________ From: Jim Jobe <jimjobe1@...> To: "eddystone_radio_users@..."...
2980
Gerry O'Hara
g8guh
Jun 16, 2012 2:55 pm
Hi Jim, I note that you are checking voltages with a DMM – as you imply in the discussion, these instruments (even the cheapest ones) have a high Ohms per...
2981
Jim Jobe
jimjobe1
Jun 16, 2012 3:44 pm
 Hi Gerry, I take on board all you've said. That's a useful tip on how to simulate a low impedance meter and I'll try that for comparison purposes. I've been...
2982
Gerry O'Hara
g8guh
Jun 16, 2012 5:33 pm
Hi Jim, Yes, there is still that original issue and as I think Roy noted, most likely a component problem on the circuits supplied by the stabilizer (have you...
2983
Jim McGowan
jim245185
Jun 16, 2012 6:29 pm
Hi Gerry , on another subject , regarding the AFseries of transistors does Tor say that the biasing resistors need changing to different values if AF types are...
2984
tor_marthinsen
Jun 16, 2012 6:37 pm
Hi Jim, I've with interest read about your problems with your 680X. You say that the current through R66 is 47mA, I assume that the voltage at point F- is...
2985
Jim Jobe
jimjobe1
Jun 16, 2012 9:20 pm
Many thanks Tor. I actually measured the current through R66 by detaching one of its leads and inserting a millivoltmeter in series. I'll put a resistor in...
2986
Jim Jobe
jimjobe1
Jun 16, 2012 9:29 pm
First thing I did Gerry and I also pulled the Oscillator, BFO and Mixer valves with no change in current drawn. The Stabiliser anode is at 151V so the excess...
2987
Jim Jobe
jimjobe1
Jun 17, 2012 4:48 pm
I've connected 2X22ohm and a 33ohm resistor temporarily in series with the mains input and got the voltages down more or less where they should be. I've also...
2988
Gerry O'Hara
g8guh
Jun 17, 2012 9:44 pm
No, I believe they are direct substitutes. Gerry From: eddystone_radio_users@... [mailto:eddystone_radio_users@...] On Behalf Of...
2990
py2lsb
Jun 20, 2012 2:31 am
Greetings friends of the group. Today is a happy day for me, found in Brazil S680x Eddystone in a reasonable state of repair and working very well. As I said...
