Goin' portable

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schroeder1976
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Goin' portable

Post by schroeder1976 » 06 Sep 2019 16:06

Hi people,
just for curiosity and to get me a gadget, I bought a used Pathè-Marconi PE1 (at a very good price), their version of the soundburger. I will receive it in a few days, it is sold as "perfectly working"
Since I'm a record shopaholic and buying records while I'm around (for work or vacation) is always a pain, since you have to wait until you're back home, I wanted something acceptable to bring along.
After discarding Sony Flamingo and Audio-Technica original soundburger (both are now too much into collectible gadgets, and their price is too far over their value, even taking the risk of buying a not-working one to try to fix it), I saw some demos about this one that made me think that this could be a good choice.

As far as I could see, the same "turntable" was made by a single, unknown, Japanese factory, and then branded in various ways
Dual prp5
Pathè-Marconi PE1
Nordmende Dingi RP 200
Saba McDisc
Thomson TL-200

However, I've not been able to find out a service manual (or either a user manual!) for any of these five models: in fact, the one I will get will surely need a new stylus and it will likely be necessary to replace the belt(s) as well (I can do that, but I need to know which belt(s) are...).
After some research, I found that the stylus should be the Dual DN 105 (with a quite good 2gr tracking force).

If anybody of you has any kind of documentation or first-hand information it would be quite helpful.

I will keep you posted on how it is going on...
Schroeder


PS: Somebody claims that this device is identical to the Audio-Technica AT727 (Soundburger or Mister Disc), which has been also sold in a rebranded way as Hitachi HT03; however the external shell looks different and also the stylus (AT103) looks different from the DN105. If it was the case this would solve my problems in terms of spare belts because they seem to be more easy to find on eBay...

circularvibes
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Re: Goin' portable

Post by circularvibes » 06 Sep 2019 18:06

Thanks for all the info. I never have heard of many of these models. I would not mind owning one myself one day. If you Google Pathè-Marconi PE1, you will come up with the Radio Museum site which at least has the chematic and a few pretty pictures. You will have to sign up to download them.

schroeder1976
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Re: Goin' portable

Post by schroeder1976 » 09 Sep 2019 13:46

I got the info from Radio-Museum site (which hosts part of the documentation - not complete, unluckily - of the Dual and the Saba. The part codes, for example, are internal codes and this is not making think easier in guessing, e.g., the details about the belts).
As far as it seems, each brand was printing its own handbook, but they were sharing the pictures. The part codes are different for each brand since everybody was providing its own code.
However, if anybody should have more info about those machines it will be nice. I'll let you know the impressions as soon as the baby will arrive.

schroeder1976
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Re: Goin' portable

Post by schroeder1976 » 30 Sep 2019 16:09

Ok, quick update. The PE1 did make it to my home and I did a quick test on it: the stylus must be replaced but was good enough to do a first run that worked fine. I have some noise when moving the volume control but this might be due to dirt on contacts, I will spray it a bit in order to see if it goes better: what is a bit annoying is that I have a continuous noise on both the earphones that may be due to the power supply (it is a generic one, I will try with a better one and also with batteries, that I had not at home at the moment).
I listened to a couple of records that were running slow: this is due to loose belts (after more than 30 years, this is understandable). Therefore I opened it and, comparing it to some AT727 servicing videos I found on YT, I can confirm that this is quite similar to the AT727. If put near the AT727, in fact, the two models would seem twin versions of the same idea, having as differences

a. the headshell and the cartridge
b. the plastic shell, that in one case is rounded on the disc side, and in the other is square.
c. The presence of the metal hook to keep the headphones cable away from the tonearm (only AT)
d. the way to lock the tonearm during transport (AT uses the 45rpm adapter, the other hooks it to the spindle)
e. the buttons are the same but they have a different shape
f. the presence of a screw for the motor fine-tuning (only AT, it seems: I am checking if it exists actually also in the other one but it is not made available outside)

Each one of the models, basically, seem a different development of the same core: each one has its pros and cons, but they just seem to be two solutions to the same problem

I am trying to see if the belts of AT727 are fine (dimensions are roughly compatible, after measuring them with a ruler): the service manuals I found on the web (saba and dual), unfortunately, don't supply the parts specification but only the catalog number, that is different from brand to brand (I wrote Dual to ask for info, but they answered me that this was a part supplied from a third-party provider and that they have no specs about it). Following this similarity, I have just ordered AT727 belts, I will let you know how it goes.

edradour
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Re: Goin' portable

Post by edradour » 30 Sep 2019 16:56

Another avenue - PE makes me think Perpetuum Ebner, a German manufacturer of TTs in the 50s and 60s - later absorbed by Dual IIRC. They did make at least one miniature model (I had one mounted on a tiny plinth) and supplied other makers. If you could post a pic of the headshell I'll see if I can compare it with my hazy memory of the one I had.

Alec124c41
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Re: Goin' portable

Post by Alec124c41 » 30 Sep 2019 21:57

There are generic belts, that are specified by size: length, width, and thickness.The rule of thumb for length is the length of the belt path, tried with a bit of string if necessary, minus 5 percent.

Cheers,
Alec

schroeder1976
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Re: Goin' portable

Post by schroeder1976 » 03 Oct 2019 16:34

Hi folks
test is proceeding. The device is working fine, actually: I'm still using the "original" belts, so it's a bit slow but that's not a problem. The cartridge with the new stylus is pretty decent and I'm noticing that it's sounding much better with an ampli on the RCA speakers than using the headphones (dynamics, for example, seem much better out of the RCA), but that's not a particular matter.
I noticed that it has a lot of hum that I wasn't expecting. Its sources seem to be two
a. the motor
b. the DC supply
The motor one is present also when I'm using batteries, while obviously I can hear both of them when I have a power plug in inside. Note that the AC/DC supply is not the original one and that I had only one AC/DC converter at home (a cheap one) so I still have not checked if it is my one that is particularly noisy, however I'm using it all the time and I never noticed this kind of problems. I'm going through the PCB to see if I can figure something out...

Coffee Phil
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Re: Goin' portable

Post by Coffee Phil » 03 Oct 2019 17:59

Hi schroeder1976,

Assuming that your circuit is the same as the Audio Technica Mister Disc, there is an active filter feeding power to the audio electronics. It is there to filter crap from the motor circuit or wall wart. It consists of TR1, R303, and C301. Check to see if there is ~0.7 volt drop from the collector to the emitter of TR1 and also if C301 is good.

I run my Mister Disc from an iPhone USB charger via a cable I made from an old iPhone cable with a bad mini USB connector.

Phil

schroeder1976 wrote:
03 Oct 2019 16:34
Hi folks
test is proceeding. The device is working fine, actually: I'm still using the "original" belts, so it's a bit slow but that's not a problem. The cartridge with the new stylus is pretty decent and I'm noticing that it's sounding much better with an ampli on the RCA speakers than using the headphones (dynamics, for example, seem much better out of the RCA), but that's not a particular matter.
I noticed that it has a lot of hum that I wasn't expecting. Its sources seem to be two
a. the motor
b. the DC supply
The motor one is present also when I'm using batteries, while obviously I can hear both of them when I have a power plug in inside. Note that the AC/DC supply is not the original one and that I had only one AC/DC converter at home (a cheap one) so I still have not checked if it is my one that is particularly noisy, however I'm using it all the time and I never noticed this kind of problems. I'm going through the PCB to see if I can figure something out...

schroeder1976
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Re: Goin' portable

Post by schroeder1976 » 13 Oct 2019 21:41

So, here's an update,
Coffee Phil is absolutely right: there is a circuit and I have the suspect that the BJT is not working (seems to be in short). I am checking how to replace the BJT to make it work.

In the meantime, I received a REAL SoundBurger (bought at an auction at about 100 Euros as "not checked": it needed the belts to be changed and a new stylus: I found a NOS of the original Audio Technica stylus and I am waiting for it) so I am comparing the two ones just based on the design.

I confirm the previous impression: they may be a clone, they may be two results of the same project.
I would not say that one is better than the other: the only points of TRUE difference is
a. Audio-Technica locks the tonearm in a way that is much more complex but much more effective.
b. Audio-Technica version has a better displacement for RCA, earphones and power supply (even if I need to confirm it after I will have finished the checks on the circuit that should filter interferences between power supply and audio amplifier, having them all on the same line does not seem too much a bright idea from me).

To go more into detail: the PCB is the same but redesigned (a few details change but nothing dramatic: for example the fine-tuning for the rpm is done with 20k VRs in one case, 5k VRs in the other case). No particular changes. The motor position changes by 90 degrees (allowing to save 2-3 cms in length).
To say it in other words: if these have been cloned by different companies, well, this is a damn good clone. I am truly impressed. This is why I still suspect that AudioTechnica (or some other Japanese company) did two slightly versions of the same device, one to be marketed as AudioTechnica and the other one that would become Dual/SABA/PatheMarconi/whoever-will-want-it.

However, while servicing the "real" soundburger I broke the VR of 45rpm, the one in the picture. Do you have any Idea on where I could find another one to replace it? It is a simple 5k RV with access to the screw on both sides, however I was not able to retrieve a similar one anywhere :-(

https://scontent.fmxp5-1.fna.fbcdn.net/ ... e=5E2B1357

kalaur
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Re: Goin' portable

Post by kalaur » 14 Oct 2019 05:16


Coffee Phil
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Re: Goin' portable

Post by Coffee Phil » 14 Oct 2019 17:54

Hi schroeder 1976,

I'm not sure the little open frame pots are still available but you should be able to use what kalaur linked. They are likely much better anyway.

If you are having trouble finding a 2SD-471 transistor, a PN2222A should be fine and they are common as dirt in the USA.

https://www.mouser.com/Search/Refine?Ke ... 1NEALw_wcB

Mind the pin connections. Check the data sheet of the PN2222A.

Phil

schroeder1976
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Re: Goin' portable

Post by schroeder1976 » 22 Oct 2019 11:18

Hi all,
another update: I received yesterday a NOS original Audio Technica stylus and so I had the chance, finally, to test one record on my AT 727. I had already noticed that the amplifier needs to "warm-up" (!), or better, that between when you turn it on and when you gradually start hearing at least a background hiss it takes 30-40 secs, which does not seem normal on an IC amplifier; this was suggesting me that some caps could be out of order. Yesterday I had the confirmation because, on finally hearing some music coming out of it, the volume is quite low on both earphone outputs, and pretty noisy as well. Therefore I suppose I'll have to find one or two free days in order to start recapping it (it would be strange that both the TA7331p are gone, but in case I'll change them either, they're easy to find at 2-3 euros each). From the smell of mold that came out of the case when I first opened it I suppose that it must have been stored in a damp cellar for years. Rats.

Instead, the PE1 got lots of output volume (using the earphones you cannot go over 50% of the volume wheel, because it's getting too loud) and its only problem (but not too bad, it allows you to use the turntable anyway) is the noise filter we discussed above, where I should replace the 2SD-471 that is actually gone (according to the meter): this explains, as you suggested here before, the unexpected power supply noise.

Just to continue with the comparison: even with poorer amplification quality, the sound quality of the Audio Technica cartridge with its original stylus seems much better than the dual one, but I'll be able to confirm it as soon as both amplifiers will be up and running again.

Final note: it is very interesting to note that, even if detailed circuit schemas were part of the servicing manual, the instructions for servicing asked for a replacement of the complete board in case of amplifier problems (and in fact the spare part list does not list all the components, but considers the whole board as a single spare part)

Will update you as soon as I have some time to play with caps :-)

However, on thursday I will use my PE1 during a lesson on classical music where I will play several LPs: much more nice that having a USB key with a bunch of files on it, isn't it?

Coffee Phil
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Re: Goin' portable

Post by Coffee Phil » 23 Oct 2019 18:13

Hi Schroeder1976,

I would suggest that you do a bit more troubleshooting and even replace the electrolytic caps before changing the ICs. It is hard to imagine how an IC could require a warm up time. Those boards are some sort of phenolic as opposed to fiberglass-epoxy so it is hard to change a dual-inline part without lifting traces.

Phil
schroeder1976 wrote:
22 Oct 2019 11:18
Hi all,
another update: I received yesterday a NOS original Audio Technica stylus and so I had the chance, finally, to test one record on my AT 727. I had already noticed that the amplifier needs to "warm-up" (!), or better, that between when you turn it on and when you gradually start hearing at least a background hiss it takes 30-40 secs, which does not seem normal on an IC amplifier; this was suggesting me that some caps could be out of order. Yesterday I had the confirmation because, on finally hearing some music coming out of it, the volume is quite low on both earphone outputs, and pretty noisy as well. Therefore I suppose I'll have to find one or two free days in order to start recapping it (it would be strange that both the TA7331p are gone, but in case I'll change them either, they're easy to find at 2-3 euros each). From the smell of mold that came out of the case when I first opened it I suppose that it must have been stored in a damp cellar for years. Rats.

Instead, the PE1 got lots of output volume (using the earphones you cannot go over 50% of the volume wheel, because it's getting too loud) and its only problem (but not too bad, it allows you to use the turntable anyway) is the noise filter we discussed above, where I should replace the 2SD-471 that is actually gone (according to the meter): this explains, as you suggested here before, the unexpected power supply noise.

Just to continue with the comparison: even with poorer amplification quality, the sound quality of the Audio Technica cartridge with its original stylus seems much better than the dual one, but I'll be able to confirm it as soon as both amplifiers will be up and running again.

Final note: it is very interesting to note that, even if detailed circuit schemas were part of the servicing manual, the instructions for servicing asked for a replacement of the complete board in case of amplifier problems (and in fact the spare part list does not list all the components, but considers the whole board as a single spare part)

Will update you as soon as I have some time to play with caps :-)

However, on thursday I will use my PE1 during a lesson on classical music where I will play several LPs: much more nice that having a USB key with a bunch of files on it, isn't it?

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