Bush SRP31D.

[anthony lawrenc]

Hi everyone,

Got this Bush given from a friend's mum. She tells me it's been in the cupboard under the stairs for years. It only came to light because she is having a new electric meter fitted.

Anyway I get it home and power it up with a lamp limiter but the lamp didn't light at all. I put a record on and it played although not very loud. I have tested the cartridge and it's fine. I know that caps will need replacing but which ones? can anyone tell me?

I already have an SRP31C. I have opened that one just to compare the two machines and apart from the obvious cosmetic diffrences and the turntable they look almost the same. The only difference I can spot is the valves [31D has 2 x ECL86, the older one has ECL83's].

I seem to remember reading somewhere on here that the 31D had a more powerful amp; anyone know what the output should be?

I would also like to ask about the Selenium rectifier but that can wait till a later date.

Thanks,
Anthony.

[AndiiT]

Hi,
I have owned both an SRP31C and SRP31D. The main difference between the two are that the C version uses ECL83 valves and, usually, a Garrard deck (there were a few different types fitted) the D version has ECL86 valves, a higher output and almost exclusively is fitted with a BSR UA16 deck.

Both models are fitted with an option to fit an additional external amplifier for Stereo working, but not all models are fitted with a stereo cartridge/stylus assembly.
The C and D models were fitted with Tape output sockets, whilst the original SRP31 was not.

Getting back to your problem of low output I have had the selenium rectifier cause this fault, due to low HT. If you do a search around the forums for Bush SRP31 and maybe also Selenium rectifier I suspect that you will find some useful information on how to go about replacing it with a silicon counterpart.

Regards
Andrew

[anthony lawrenc]

Hi guys,

After replacing all the caps the r/player is working a treat. However after everything I've read on Selenium rectifiers I would like to replace it as well, before I reassemble the unit.

I have the correct diode and a 100 ohm 6 watt resistor. What I want to know is where to put the resistor? before or after the diode?

Thanks for all the excellent advice.
Anthony.

[wave solder]

It makes no difference whether the resistor goes before or after the diode as they are connected in series.

[anthony lawrenc]

hello again i have fitted the diode and resistor and evrything is workin g well sounds great thanks again guys Anthony

[anthony lawrenc]

Hi again everyone,

I thought this machine was cured but no it's working ok but when I compare it with the 31C there is a noticable difference in the output. I don't just mean volume, there's a distinct lack of treble and bass. The older machine has a much richer sound, that's the only way I can describe it.

Could the big metal can (two in one) cap be the problem? I have measured the voltage at this cap and am geting 259VDC on one leg and 229VDC on the other. I also measured the same points on the 31C the voltage is slightly higher [only about four or five volts].

Any ideas guys?

Cheers,
Anthony.

[ben]

what cartridge is fitted? you may well need a new one.

[Nickthedentist]

The ~2% discrepancy in voltage is unlikely to be a problem.

As Ben says, the cartridge is the most likely culprit by far. Can you swap the two over?

Nick.

[anthony lawrenc]

thanks guys will swap the carts and see what happens and let you know Anthony

[fronker]

I wonder what happened?

Regarding the volume I have the same problem. I had ed dining forum member look it over when I got this machine and he said he replaced the HT. I have no idea what that is.

Anyway the volume was quite low which ed said was normal, however I found out if I moved the head of the arm around a little while playing, the volume would all of a sudden boost up as if the needle hit the grooves properly.

Anyway it now plays louder, although the needle in one of the two settings is very wobbly, and more concerning is that the records definitely change shade when I play them. I have no idea if this is normal. When ed looked at it he said he'd had the needle under the microscope and all was well.

Anyway I'm very confused and don't really want to play my vinyl which was the point of getting the system. Any help would be appreciated.

[Audio1950]

Something is seriously wrong if you can see the record changing colour when played!
Presuming the original cartridge is still fitted, it will be a Sonotone 8TA, (red plastic body, gold coloured double stylus?). These frequently suffer from the stylus having been removed wrongly in the past, and consequent opening of the little black spring clip that holds the stylus. If you can remove the cartridge, you may be able to carefully push the clip down a bit with a small screwdriver, which will hold the stylus more securely. This can't really be done with the cartridge in place, as the whole thing will bend upwards, due to it's flexible mounting bracket. This however, should not be the cause of the wear on the record that you mention. It may well be that although the stylus was perfect when Ed checked it, it may have been damaged since, as it sounds like a chipped stylus which is damaging your records, or the playing weight is far too heavy. It is very easy to let the arm fall on the baseplate and chip the stylus. I would recommend that you get a new stylus, and before fitting, check the playing weight, which should be between 5-7 grammes.

Barry

[fronker]

Hi barry, thanks a lot for your input.

Yes that is the cartridge that is on the player. I've decided I'm going to replace that as well as the stylus. For peace of mind.

One question I have is regarding the weight, and sorry if these are stupid questions, but how do I measure the weight of the arm and more so how do I then change it?

Cheers

[Audio1950]

These certainly are not stupid questions, we are all learning all the time!

To measure the playing weight, you really need a stylus pressure guage, but they tend to be a bit expensive if you are only going to use it once. Get the new cartridge and let me know, and I'll pop mine in the post for you, and you can return it when you've finished with it.

To adjust the weight, if you lift the arm up to a vertical position, you'll see a spring attached to the bracket at the base of the arm, and at the other end of the spring is a hook, which you take out of whichever hole it's in now, and either move it to a hole nearer the centre of the arm to decrease the weight, or nearer the base of the arm to increase the weight.

Barry

[julie_m]

You can get small electronic scales from new age gift shops. Place the scales on the stationary turntable and lower the stylus gently onto the centre of the weighing platform.

The pickup cartridge is counterbalanced by a spring underneath the tonearm, and there should be some means of adjusting the tension in the spring -- a piece of metal that sits between turns, a set of holes to hook it into, or a screw adjuster.