Bush SRP31D.... - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Station X · 27th Dec 2018, 1:33 pm

Those aren't Hunts capacitors, they're Plessey electrolytics and are clearly labelled as such. The low voltage on C10 will result in excess anode current being drawn by the output valves.

When you remove the old caps check that R15 and R3 haven't changed value.

The coupling capacitors (that/those capacitors) are C7 and C8, which I think are on the other side of the board on the feedthrough insulators? They don't look like Hunts waxed paper capacitors either.

Paulus.d · 27th Dec 2018, 1:37 pm

Excellent ..... thank you !!!!

Paulus.d · 27th Dec 2018, 2:14 pm

Hunted around . . . can't find any 50uf 25v anywhere !!!

Station X · 27th Dec 2018, 2:21 pm

47uF will do.

ms660 · 27th Dec 2018, 2:27 pm

Quote:

Originally Posted by Paulus.d

Mainly concentranting on those horrible Hunts caps, C4 and C10, the DC voltages there are lower than the diagram says. Instead of 1.5V it reads 0.97V and instead of 12V it's 5.5V.

5.5 volts across C10 sounds about right to me unless I'm looking at the wrong schematic.

Lawrence.

Station X · 27th Dec 2018, 3:03 pm

I only have the manufacturer's sheet for the SRP31C and it says 12V.

Perhaps you have the correct circuit for the SRP31D?

EDIT You're right:-

https://www.vintage-radio.net/forum/...03&postcount=4

I'd still change those Plessey caps though.

ms660 · 27th Dec 2018, 3:08 pm

https://www.vintage-radio.net/forum/...1&d=1342476743

There's also one in a youtube video, don't want to post that link incase it breaches forum rules.

So far as I can make out from the photo's the output valves cathode bias resistor fitted is 120 ohms which would tally up with the D version (ECL86's)

Lawrence.

Paulus.d · 27th Dec 2018, 3:11 pm

I've been through boxes of electronic stuff and bits of circuit boards....I cant find a 47uf cap at all !
Perhaps I should test the speaker and another input source to see if the fault persists...

Paulus.d · 27th Dec 2018, 4:05 pm

Okay .... you guys ready for this?
another input source had the same effect.. but ..
Another speaker sounds fine !!

The speakers naff........the tweeter too...

Paulus.d · 2nd Jan 2019, 12:15 pm

Rght the speakers been replaced and the plessey caps..... it still sounds horrible ..
the distortion is still present on the speaker ... in fact it sounds worse due to the clearer sound !

Paulus.d · 2nd Jan 2019, 3:08 pm

Hahaha noticed the speaker sounds okat when not screwed to the case! The cone was bashing against the wood inside the cut out....
stood the speaker off with a few spacers ... sounds as sweet as a nut ....
The record decks speed is a little off and takes time to reach maximum...
Gonna look into that next ...

Edward Huggins · 2nd Jan 2019, 5:48 pm

You may loose some Bass (that speaker is plenty small enough) by standing the speaker off from the baffle board. I would make a corrugated card template to fit between the speaker chassis and the baffle, making sure the periphery of the speaker cone is in no way masked/obscured.

Paulus.d · 2nd Jan 2019, 6:43 pm

Having already serviced the UA16, it's still running slow... About a semitone to my ears..I've lubricated, cleaned and checked motor bearings ...
It has superb trackion ... you can't stop the turntable turning!
Has there ever been issues with the spindle or actual motor in these decks?

The speaker sounds fine to my ears ....the amps voltages are spot on and i've changed the Plessey caps
Paul

Paulus.d · 4th Jan 2019, 11:13 am

No good ....it starts at almost zero turning at first then warms up ....
did put a post wanted for a spare motor to try in it .... will just measure the incoming volts as a precaution
Paul

27th Dec 2018, 1:33 pm	#21
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,287	Re: Bush SRP31D.... Those aren't Hunts capacitors, they're Plessey electrolytics and are clearly labelled as such. The low voltage on C10 will result in excess anode current being drawn by the output valves. When you remove the old caps check that R15 and R3 haven't changed value. The coupling capacitors (that/those capacitors) are C7 and C8, which I think are on the other side of the board on the feedthrough insulators? They don't look like Hunts waxed paper capacitors either. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

27th Dec 2018, 1:37 pm	#22
Paulus.d Hexode Join Date: Mar 2008 Location: Margate, Kent, UK. Posts: 355	Re: Bush SRP31D.... Excellent ..... thank you !!!!

27th Dec 2018, 2:14 pm	#23
Paulus.d Hexode Join Date: Mar 2008 Location: Margate, Kent, UK. Posts: 355	Re: Bush SRP31D.... Hunted around . . . can't find any 50uf 25v anywhere !!!

27th Dec 2018, 2:21 pm	#24
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,287	Re: Bush SRP31D.... 47uF will do. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

27th Dec 2018, 3:03 pm	#26
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,287	Re: Bush SRP31D.... I only have the manufacturer's sheet for the SRP31C and it says 12V. Perhaps you have the correct circuit for the SRP31D? EDIT You're right:- https://www.vintage-radio.net/forum/...03&postcount=4 I'd still change those Plessey caps though. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

27th Dec 2018, 3:08 pm	#27
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Bush SRP31D.... https://www.vintage-radio.net/forum/...1&d=1342476743 There's also one in a youtube video, don't want to post that link incase it breaches forum rules. So far as I can make out from the photo's the output valves cathode bias resistor fitted is 120 ohms which would tally up with the D version (ECL86's) Lawrence. Last edited by ms660; 27th Dec 2018 at 3:11 pm. Reason: Addition

27th Dec 2018, 3:11 pm	#28
Paulus.d Hexode Join Date: Mar 2008 Location: Margate, Kent, UK. Posts: 355	Re: Bush SRP31D.... I've been through boxes of electronic stuff and bits of circuit boards....I cant find a 47uf cap at all ! Perhaps I should test the speaker and another input source to see if the fault persists...

27th Dec 2018, 4:05 pm	#29
Paulus.d Hexode Join Date: Mar 2008 Location: Margate, Kent, UK. Posts: 355	Re: Bush SRP31D.... Okay .... you guys ready for this? another input source had the same effect.. but .. Another speaker sounds fine !! The speakers naff........the tweeter too...

2nd Jan 2019, 12:15 pm	#30
Paulus.d Hexode Join Date: Mar 2008 Location: Margate, Kent, UK. Posts: 355	Re: Bush SRP31D.... Rght the speakers been replaced and the plessey caps..... it still sounds horrible .. the distortion is still present on the speaker ... in fact it sounds worse due to the clearer sound !

2nd Jan 2019, 3:08 pm	#31
Paulus.d Hexode Join Date: Mar 2008 Location: Margate, Kent, UK. Posts: 355	Re: Bush SRP31D.... Hahaha noticed the speaker sounds okat when not screwed to the case! The cone was bashing against the wood inside the cut out.... stood the speaker off with a few spacers ... sounds as sweet as a nut .... The record decks speed is a little off and takes time to reach maximum... Gonna look into that next ...

2nd Jan 2019, 5:48 pm	#32
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,327	Re: Bush SRP31D.... You may loose some Bass (that speaker is plenty small enough) by standing the speaker off from the baffle board. I would make a corrugated card template to fit between the speaker chassis and the baffle, making sure the periphery of the speaker cone is in no way masked/obscured. __________________ Edward.

2nd Jan 2019, 6:43 pm	#33
Paulus.d Hexode Join Date: Mar 2008 Location: Margate, Kent, UK. Posts: 355	Re: Bush SRP31D.... Having already serviced the UA16, it's still running slow... About a semitone to my ears..I've lubricated, cleaned and checked motor bearings ... It has superb trackion ... you can't stop the turntable turning! Has there ever been issues with the spindle or actual motor in these decks? The speaker sounds fine to my ears ....the amps voltages are spot on and i've changed the Plessey caps Paul

4th Jan 2019, 11:13 am	#34
Paulus.d Hexode Join Date: Mar 2008 Location: Margate, Kent, UK. Posts: 355	Re: Bush SRP31D.... No good ....it starts at almost zero turning at first then warms up .... did put a post wanted for a spare motor to try in it .... will just measure the incoming volts as a precaution Paul