Problem with Leak Stereo 30 Plus - Left Channel [Archive]

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pbroido

11-02-2018, 22:08

Hi

I have a Leak Stereo 30 Plus which seems to have issues with one of the channels. When I got it, it had all the usual signs of sitting in a corner for years gathering dust. After spraying all the pots and switches and taking out the boards and cleaning the contacts with emery paper all the crackling etc seems to have disappeared. I do have a problem though that one of the channels is not working.

When connected to Replay: With the Tape Monitor off it plays through the Right Speaker. Tape Monitor on and it plays through both left and right.

When connected to Tuner 2: With Tape Monitor off it plays through Right Speaker. Tape monitor on it does not play through either speaker.

I have swapped the preamp boards around and then I get sound out of the Left Speaker in the above scenarios, so I guess the board itself is the problem. I also assume the Replay / Tape Monitor on bypasses the preamp boards?

Being a novice with electronics I was wondering if there was a way to diagnose the problem on the preamp board (any usual suspects)?, or should I look to find a replacement board that may be lying around?

Any advice appreciated

nutteronthebus

12-02-2018, 09:21

Hi try this site as they are in London http://www.michaelmauricerepairs.co.uk/hifi-stereo-cd-cassette-record-repair.shtml

Dave

walpurgis

12-02-2018, 09:41

I wouldn't throw too much money at a Leak Stereo 30 Plus. You can easily invest more money than the amp is worth in getting repairs done and it's not the greatest amp around in the first place. If it's not an easy fix, put it away or sell it as it is. Your cash could be better spent on an alternative amp.

Macca

12-02-2018, 10:08

I disagree, their only issue is a lack of power. Otherwise they are very open and sweet-sounding. Worth fixing IMV.

pbroido

12-02-2018, 13:47

Thanks for the feedback. The purchase was largely nostalgic as this was the amp my father had and I spent hours listening to in my teenage (and pre teen) years. Even switching it on with that click of turning the volume knob bought back memories. I paid £40 for it so not a major drain on the finances. I was more concerned about arriving home with another piece of kit and my wifes reaction :)

Other that memories I was looking for a low powered amp to drive my early Klipsch Heresy's. The little listening I have managed through the combination when the preamp section is skipped sounds quite promising.
So if I can pick up a preamp board going as parts or can fix the existing one for not much money I would consider it mission accomplished.

@nutteronthebus - thanks for the link, Ill give them a shout and see if they can help.

Lawrence001

12-02-2018, 23:34

When there are old plug in boards, it's always worth checking the plugs or pcb contacts and sockets for corrosion or oxidation, a bit of servisol or deoxit should sort that.

Sent from my BLN-L21 using Tapatalk

nutteronthebus

14-02-2018, 10:24

on ebay there is a Leak stereo 30 book https://www.ebay.co.uk/itm/VINTAGE-LEAK-STEREO-30-PLUS-MANUAL-INSTALLATION-OPERATION-MAINTENANCE/162875906117?hash=item25ec291845:g:OhwAAOSwU91aZIt F

Dave

nutteronthebus

16-02-2018, 18:14

hi this is a cct diagram of the Leak

Dave

pbroido

16-02-2018, 19:27

Thanks Dave,
The weekend is here so I can play with the amp a little more. Bought some Deoxit to see if that sorts out the channel issue. I fear that I am going to need to buy a bust up Stereo 30 Plus going for parts to sort out my problem.
Will let you know how I get on this weekend.

P

snowman_al

17-02-2018, 06:54

pbroido

17-02-2018, 10:41

I would fix it too if it were mine. Not a great amp, but easy to work on and pleasant to listen to.

I expect you have seen this epay listing?
https://www.ebay.co.uk/itm/Leak-Stereo-30-or-70-parts/292447215459?epid=110968918&hash=item4417365f63:g:IFAAAOSwLwBagfg9

I saw the ebay auction and ignored it as it said Stereo 30 and 70 parts. On a closer look the boards look like the Stereo 30 Plus PReamp boards (S70PR).

pbroido

17-02-2018, 11:24

snowman_al

17-02-2018, 18:21

I'm 90% sure they are Stereo 30 Plus boards / parts. For these reasons:

They cannot be from a Stereo 30, they do not have boards.
The component values on the ''OPA'' boards are typical 30 plus values. R42 is 12k ohms (brown red orange), R45 is 3.9k ohms (orange white red) and R49 is 22k ohms (red red orange). These values are 22k, 6.8k and 33k on Stereo 70s.
And the ad does say the volume pot has a mains switch, the Stereo 70 has a push button on/off.

But, I've not seen one in a long time, and have never had both at the same time - so without a reference model I'm not 100% sure.

By the way, the pre-amp boards can go in either the left or right channel. But you should keep the driver boards (OPA boards) in their original locations as the idle current setting/adjustment will be specific to the output transistors.

Pictures of the faulty board might give a clue?

pbroido

18-02-2018, 12:20

Thanks that all seem to stack up and thanks for the advice.
The board does look identical to mine too.

I asked the seller and he said he was not aware there was a 30 Plus so maybe just a confusion.
Other than the fact that I will need to pay almost as much as I paid for the amp (£30) to get the board (£19.90 +£5.65pp), I'll probably go for it.

Its great to have the amp I grew up with and it does sound wonderful at the moment when bypassing the preamp (replay / tape monitor) through my Klipsch H700.
(This usually queues the Leak and Heresy haters :) )

Macca

18-02-2018, 14:23

Its great to have the amp I grew up with and it does sound wonderful at the moment when bypassing the preamp (replay / tape monitor) through my Klipsch H700.
(This usually queues the Leak and Heresy haters :) )

I bought one in mint condition with the tuner from the daughter of some old boy who had either died or gone into a home. I didn't really need it but it was only £20 for the pair. I leant it to a friend and he used it for several years with a tape deck and some small, unbranded speakers. He was getting a very listenable, tuneful sound, very open and sweet. Better in a lot of ways to what I was getting with equipment I'd paid proper money for. I'd guess that the Heresys are a really good match for that amp. Very efficient so the lack of power does not matter, and the natural sweetness of the Leak taking the potentially hard and shouty edge off the speakers.

snowman_al

22-02-2018, 09:10

If you have not got your amp sorted yet these might be of interest?

https://www.ebay.co.uk/itm/Pre-Amplifier-modules-for-Leak-Delta-30-amplifier/273079757431?hash=item3f94d26a77:g:u~oAAOSwVnlajha z

pbroido

22-02-2018, 15:28

Thanks Alan,
I have been keeping an eye out for some. You seem to be quicker on ebay than me :) These have gone already.
Ill continue to look if something comes up at a "reasonable" price or my patience wanes.
If I get some time I may tinker with the board itself.

pbroido

08-03-2018, 10:11

Does anyone know if the Leak Delta 30 preamp boards are the same as / compatible with the Stereo 30 plus?
The internals look very similar but I don't seem to be able to fund any documentation or images of the Delta 30

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snowman_al

08-03-2018, 16:16

Yep, the pre-amp boards are just the same. The Delta 30 is a Stereo 30 Plus in new clothes.
The component values are the same as are the connections.
I would expect the components might be different styles and or makes, but that does not alter their functionality. If in doubt change them as a pair.

A quick search around also confirms that the pre-amp boards are common to the Leak Stereo 30 Plus, Delta 30, Leak Stereo 70, Delta 70 and even the Wharfdale Linton amplifier of the same Rank take over period.

Good luck! Alan

pbroido

08-04-2018, 17:02

Finally got the Left channel sorted out. I managed to find a set of Preamp boards from a Stereo 70 on the forum. (Thanks Dan)

In my attempt to fix the board I did find out that the little inductor on the preamp PCB is a common culprit when trying to debug an issue on these amps. They are very flimsy and tend to break in transit.
It has left me with 2 boards out of 4 I landed up with with broken inductors. If anyone knows if there is a simple replacement for these I would not mind seeing if I can get them working. Nothing important as it will fall to the back of list of little diy jobs I have lined up.

Firebottle

08-04-2018, 17:57

Any idea what the value of the inductor is? I have a bit of a stock so you would be welcome to a couple if they are the right value.

Loving the avatar :)

pbroido

08-04-2018, 21:40

Any idea what the value of the inductor is? I have a bit of a stock so you would be welcome to a couple if they are the right value.

I have a schematic of the preamp board (S 70 PR) but cannot find the values associated with each of the components. Ill dig a little more and if I come up with the values Ill get in touch.

Loving the avatar :)

Thanks, when I saw the pic first it took me right back to my early teens. Funny enough the memory was probably listening to my fathers hifi including a Leak Stereo 70 amp when I really got hooked!

snowman_al

09-04-2018, 06:41

Glad you have it sorted.

According to the circuit diagram the inductor L1 is 10mH. (http://www.angelfire.com/sd/paulkemble/sound7h.html)

Firebottle

09-04-2018, 08:50

Sorry to say but I haven't got any 10mH. :(

pbroido

09-04-2018, 11:23

According to the circuit diagram the inductor L1 is 10mH. (http://www.angelfire.com/sd/paulkemble/sound7h.html)

Thanks. A little lazy of me. There it is sitting in the middle of the diagram.