Bush SRP 31D not producing sound. - Page 6 - UK Vintage Radio Repair and Restoration Discussion Forum

AC/HL · 30th Jul 2012, 1:08 am

Just out of interest I dusted down my SRP31 tonight. HT down to 45V!
However, it gave me a chance to check my loose fuse bulb theory. It does indeed cause the output to fade, taking about 3 seconds down to stylus noise only.

Refugee · 30th Jul 2012, 1:15 am

That sounds even more like a bad heater connection now. The valve holders need to be examined very carefully.

Spencervs · 30th Jul 2012, 1:22 am

I think the valve is busted then. Just swapped them around and the glow swapped from V2 to V1... should I then assume that V2 (now V1) is dying and so needs replacing? I'm guessing that should cause the fading out? also does this mean I have to buy two? they are expensive! :S

Refugee · 30th Jul 2012, 1:24 am

It might just be a dirty pin on the valve.

Spencervs · 30th Jul 2012, 1:31 am

Given it a light scrape with a knife to clean the pins and no luck.

Refugee · 30th Jul 2012, 2:34 am

Check the pin with a meter again to see it is OK.
Then examine the holders carefully again and the wiring to them from the transformer.

AndiiT · 30th Jul 2012, 9:10 am

Quote:

Originally Posted by AC/HL

Just out of interest I dusted down my SRP31 tonight. HT down to 45V!

For the cure to the above problem see post #2 onwards in this thread

Andrew

Sideband · 30th Jul 2012, 1:42 pm

I'd go for the valveholder before the valve, very unusual to find an open circuit valve heater. Not unknown of course. More likely the holder or the heater wiring especially as it appears to be intermittent. Some valveholder contacts lose their strength and then become intermittent.

Rich.

Spencervs · 30th Jul 2012, 8:16 pm

Hmm ok, how do I check the holders though? I'm not sure if it could be them though because I swapped the valves (they are both ECL86) and the non glowing valve was the same one except in the other slot.

Station X · 30th Jul 2012, 9:31 pm

Instead of asking more questions, why don't you read some of the previous answers?

julie_m · 30th Jul 2012, 9:41 pm

You'll need a piece of wire, as near as you can get in gauge to a valve pin (30 amp fuse wire, maybe?) Try this in each of the valveholder sockets (with the power off!) to see how tightly they are gripping the valve pins.

If one of the contact inserts is broken, it might make contact at first but then lose it again with thermal expansion. It should feel different from a good contact insert.

Refugee · 30th Jul 2012, 9:54 pm

The heater sockets often fail first because they are closest to the heater in the valve itself and also they carry more current than any of the others.
Use a magnifier and a cocktail stick to wobble them and if they are no good you will see the two halves/sides moving separately.

Spencervs · 30th Jul 2012, 9:57 pm

Ah right, thanks guys! I'll check that right away, sorry I keep asking questions. I'm all quite new to this and excited too to see it working! I'm learning quite a lot

Spencervs · 30th Jul 2012, 10:48 pm

Ah ok, just done that with a large gramophone needle and found that most of them the needle wouldn't reach the bottom of the hole except for ports 5 and 7 of V1. I am guessing that this is a problem, am I right?

Herald1360 · 30th Jul 2012, 11:10 pm

Pin 5 is certainly a heater pin on most B9A valves! ECL83 and 86 included.

steve_gus · 1st Aug 2012, 12:25 pm

No reply for a couple days Spencer, hope you haven't zapped yourself!

Spencervs · 6th Aug 2012, 5:24 pm

Sorry about that. Still alive! Got some replacement valve holders and have soldered most of the points but one of the smaller resistors snapped in the process of trying to get it off. Stubborn things they seem to be, so I ordered a replacement. Will solder that in and let you know how it turns out. I have an opportunity to buy replacement decoupling capacitors. You guys reckon it's worth it? I think the ones I've seen on eBay are new old stock.

It's been quite satisfying to change that holder, thanks guys for helping me. Hope I haven't been too annoying with my onslaught of questions

AC/HL · 6th Aug 2012, 5:44 pm

It's always tricky removing wired components, as distinct from printed circuit ones, especially in Bush equipment.
This fault finding exercise is basically what we all do, the only difference is that experience allows many of the stages to be undertaken in quick succession, perhaps short circuiting a few of them.
As for NOS capacitors, paper no, plastic types yes, but thay are probably not required.

Glowing Bits! · 7th Aug 2012, 9:44 pm

If changing the valve holders does not help anything, try changing the cartridge and stylus. I've taken delivery of a Bush RP40, which is in very good nick and found the cartridge to cause a drop in output.

The cartridge will be the next thing to look at after changing the holders.

At the moment, I'd be inclined to leave the capacitors alone unless there are strange noises being created, or the whole set fades out after changing the cartridge.

Spencervs · 10th Aug 2012, 8:02 pm

I've done the valve holders so all reconnected and I found that it is still silent although at first if I pushed the potentiometer in a bit as I turned the dial nearer to the higher levels the sound cut in then went when I released the dial (although it was still quieter than it should be) it doesn't do that now though. I did see too that V1 was dimmer than V2 and I swapped them and they seemed to even out in brightness. I have a spare cartridge and tried it out and I still have nothing (BSR SC12M)

30th Jul 2012, 1:08 am	#101
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,642	Re: Bush SRP 31D not producing sound! Just out of interest I dusted down my SRP31 tonight. HT down to 45V! However, it gave me a chance to check my loose fuse bulb theory. It does indeed cause the output to fade, taking about 3 seconds down to stylus noise only.

30th Jul 2012, 1:15 am	#102
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,553	Re: Bush SRP 31D not producing sound! That sounds even more like a bad heater connection now. The valve holders need to be examined very carefully.

30th Jul 2012, 1:22 am	#103
Spencervs Hexode Join Date: Apr 2011 Location: Grove Park, SE London Posts: 382	Re: Bush SRP 31D not producing sound! I think the valve is busted then. Just swapped them around and the glow swapped from V2 to V1... should I then assume that V2 (now V1) is dying and so needs replacing? I'm guessing that should cause the fading out? also does this mean I have to buy two? they are expensive! :S

30th Jul 2012, 1:24 am	#104
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,553	Re: Bush SRP 31D not producing sound! It might just be a dirty pin on the valve.

30th Jul 2012, 1:31 am	#105
Spencervs Hexode Join Date: Apr 2011 Location: Grove Park, SE London Posts: 382	Re: Bush SRP 31D not producing sound! Given it a light scrape with a knife to clean the pins and no luck.

30th Jul 2012, 2:34 am	#106
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,553	Re: Bush SRP 31D not producing sound! Check the pin with a meter again to see it is OK. Then examine the holders carefully again and the wiring to them from the transformer.

30th Jul 2012, 1:42 pm	#108
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,566	Re: Bush SRP 31D not producing sound! I'd go for the valveholder before the valve, very unusual to find an open circuit valve heater. Not unknown of course. More likely the holder or the heater wiring especially as it appears to be intermittent. Some valveholder contacts lose their strength and then become intermittent. Rich. __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

30th Jul 2012, 8:16 pm	#109
Spencervs Hexode Join Date: Apr 2011 Location: Grove Park, SE London Posts: 382	Re: Bush SRP 31D not producing sound! Hmm ok, how do I check the holders though? I'm not sure if it could be them though because I swapped the valves (they are both ECL86) and the non glowing valve was the same one except in the other slot.

30th Jul 2012, 9:31 pm	#110
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,286	Re: Bush SRP 31D not producing sound! Instead of asking more questions, why don't you read some of the previous answers? __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

30th Jul 2012, 9:41 pm	#111
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Bush SRP 31D not producing sound! You'll need a piece of wire, as near as you can get in gauge to a valve pin (30 amp fuse wire, maybe?) Try this in each of the valveholder sockets (with the power off!) to see how tightly they are gripping the valve pins. If one of the contact inserts is broken, it might make contact at first but then lose it again with thermal expansion. It should feel different from a good contact insert. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

30th Jul 2012, 9:54 pm	#112
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,553	Re: Bush SRP 31D not producing sound! The heater sockets often fail first because they are closest to the heater in the valve itself and also they carry more current than any of the others. Use a magnifier and a cocktail stick to wobble them and if they are no good you will see the two halves/sides moving separately.

30th Jul 2012, 9:57 pm	#113
Spencervs Hexode Join Date: Apr 2011 Location: Grove Park, SE London Posts: 382	Re: Bush SRP 31D not producing sound! Ah right, thanks guys! I'll check that right away, sorry I keep asking questions. I'm all quite new to this and excited too to see it working! I'm learning quite a lot

30th Jul 2012, 10:48 pm	#114
Spencervs Hexode Join Date: Apr 2011 Location: Grove Park, SE London Posts: 382	Re: Bush SRP 31D not producing sound! Ah ok, just done that with a large gramophone needle and found that most of them the needle wouldn't reach the bottom of the hole except for ports 5 and 7 of V1. I am guessing that this is a problem, am I right?

30th Jul 2012, 11:10 pm	#115
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Bush SRP 31D not producing sound! Pin 5 is certainly a heater pin on most B9A valves! ECL83 and 86 included. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

1st Aug 2012, 12:25 pm	#116
steve_gus Retired Dormant Member Join Date: Jul 2011 Location: Northampton, Northants. UK. Posts: 86	Re: Bush SRP 31D not producing sound! No reply for a couple days Spencer, hope you haven't zapped yourself!

6th Aug 2012, 5:24 pm	#117
Spencervs Hexode Join Date: Apr 2011 Location: Grove Park, SE London Posts: 382	Re: Bush SRP 31D not producing sound! Sorry about that. Still alive! Got some replacement valve holders and have soldered most of the points but one of the smaller resistors snapped in the process of trying to get it off. Stubborn things they seem to be, so I ordered a replacement. Will solder that in and let you know how it turns out. I have an opportunity to buy replacement decoupling capacitors. You guys reckon it's worth it? I think the ones I've seen on eBay are new old stock. It's been quite satisfying to change that holder, thanks guys for helping me. Hope I haven't been too annoying with my onslaught of questions

6th Aug 2012, 5:44 pm	#118
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,642	Re: Bush SRP 31D not producing sound! It's always tricky removing wired components, as distinct from printed circuit ones, especially in Bush equipment. This fault finding exercise is basically what we all do, the only difference is that experience allows many of the stages to be undertaken in quick succession, perhaps short circuiting a few of them. As for NOS capacitors, paper no, plastic types yes, but thay are probably not required.

7th Aug 2012, 9:44 pm	#119
Glowing Bits! Octode Join Date: Oct 2011 Location: Wrexham, North Wales, UK. Posts: 1,457	Re: Bush SRP 31D not producing sound. If changing the valve holders does not help anything, try changing the cartridge and stylus. I've taken delivery of a Bush RP40, which is in very good nick and found the cartridge to cause a drop in output. The cartridge will be the next thing to look at after changing the holders. At the moment, I'd be inclined to leave the capacitors alone unless there are strange noises being created, or the whole set fades out after changing the cartridge.

10th Aug 2012, 8:02 pm	#120
Spencervs Hexode Join Date: Apr 2011 Location: Grove Park, SE London Posts: 382	Re: Bush SRP 31D not producing sound. I've done the valve holders so all reconnected and I found that it is still silent although at first if I pushed the potentiometer in a bit as I turned the dial nearer to the higher levels the sound cut in then went when I released the dial (although it was still quieter than it should be) it doesn't do that now though. I did see too that V1 was dimmer than V2 and I swapped them and they seemed to even out in brightness. I have a spare cartridge and tried it out and I still have nothing (BSR SC12M)