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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Wed 11, 2021 11:35 pm 
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Joined: Aug Mon 09, 2021 3:24 pm
Posts: 26
Okay, I understood where the confusion is coming from. In the schematic you posted before one of those tubes (V1) is listed as the amp. So the amp is both the tube and inside the chassis? And the capacitors and resistors I'll be replacing are in the chassis? What is the tube then?

I will get to working on the other parts. I appreciate your help on how to remove the different parts-- I don't think these parts have been touched in sixty years, so they're firmly in there!


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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Thu 12, 2021 12:50 am 
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Joined: Aug Mon 09, 2021 3:24 pm
Posts: 26
I got the dials removed and the washer so I have the chassis largely out (it is still connected to the unit because of two wires connected to a brown thing on the chassis, can send picture if needed). However, there’s a weird type of screw that I can’t seem to figure out that’s keeping the two metal parts of the chassis together. I attached pictures in case anyone has seen it before and can advise. There’s a more traditional screw top and then an unusual bottom. The bottom almost seems like it was split open to prevent it from being unscrewed. I can screw the top to the left, but it just goes around and around because of the bottom. Also, there are two of these and on the second, the bottom is (at least currently) not accessible.

Also, thanks tubes4life! Sorry for missing your comment before


Attachments:
File comment: Top of the screw
12C7E7F3-FA42-47E6-B3BD-AF4DC8138E1A.jpeg
12C7E7F3-FA42-47E6-B3BD-AF4DC8138E1A.jpeg [ 2.27 MiB | Viewed 749 times ]
File comment: Bottom of the screw
0261B888-EB41-4F53-A487-E1E7AD51BDEA.jpeg
0261B888-EB41-4F53-A487-E1E7AD51BDEA.jpeg [ 1.95 MiB | Viewed 749 times ]
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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Thu 12, 2021 1:10 am 
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Joined: Aug Tue 24, 2010 8:56 pm
Posts: 6195
Location: Northeast Florida
That's not a screw, it's a removable rivet. Simply stick a small flat-bladed screwdriver under the head of it and pry up

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William


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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Thu 12, 2021 1:48 am 
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Joined: Jan Wed 16, 2013 12:04 am
Posts: 2541
Location: 77001
Tfkalk wrote:
Okay, I understood where the confusion is coming from.
In the schematic you posted before one of those tubes (V1) is listed as the amp.

So the amp is both the tube and inside the chassis?
And the capacitors and resistors I'll be replacing are in the chassis?
What is the tube then?

I will get to working on the other parts. I appreciate your help on how to remove the different parts-- I don't think these parts have been touched in sixty years, so they're firmly in there!


1. On the schematic, V1 a 12SQ7 tube, is the audio frequency
amplifier (AF) TUBE.
That's what the notation means.

This tube is taking the small signal generated from the
tonearm phono cartridge and amplifying it to the next
stage of the amplifier.

1.a. The audio amplifier is the total of all the parts put
together inside and outside of the chassis.
Wires, capacitors, resistors, controls, vacuum tubes,
transformers, for example.

2. You have 3 vacuum tubes that are plugged into
tube sockets on the metal chassis.
They each have a specific function to
make the amplifier make music.
A rectifier tube, AF amplifier tube, power output tube.

When you remove a tube, one technique is to hold the
chassis with one hand, then pull up on the BASE of the
tube with a gentle but firm rotation.

Of course, never do this with the amplifier powered up,
as those tube generate great heat that will burn you.

Hotwax


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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Thu 12, 2021 3:29 am 
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Joined: Aug Mon 09, 2021 3:24 pm
Posts: 26
William: thanks!

Hotwax: thanks as well! Certainly learning a lot about the internals of my machine and how it works, if nothing else.

With the rivets off and one metal piece of the chassis removed, I can now access the internals (not great, but better). I’ve attached a picture. Is there more than I can/should remove? Or am I at the point to start buying the new resistors and capacitors?


Attachments:
File comment: Interior of the chassis
D57358B5-5E3F-4961-8440-459F9CE4D2F4.jpeg
D57358B5-5E3F-4961-8440-459F9CE4D2F4.jpeg [ 3.55 MiB | Viewed 744 times ]
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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Thu 12, 2021 2:41 pm 
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Joined: Aug Tue 24, 2010 8:56 pm
Posts: 6195
Location: Northeast Florida
Geez, no wonder it doesn't work---those paper capacitors are roasted! :shock:

You are at the point where you should start ordering parts, can't really do anything else until they arrive. You will need to know what values first. Get all of the paper capacitors in a 630v DC rating, even if the capacitor says 200 or 400v. To find out the value of each capacitor, you will need to carefully scrape away some of the wax goo until you find the printing (it'll say something like .05 mfd, .02 mfd, etc). Don't dig too deep, don't want to wipe out the printing along with the wax

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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Thu 12, 2021 5:37 pm 
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Joined: Jan Wed 16, 2013 12:04 am
Posts: 2541
Location: 77001
Tfkalk wrote:
With the rivets off and one metal piece of the chassis removed, I can now access the internals (not great, but better).
Is there more than I can/should remove?
Or am I at the point to start buying the new resistors and capacitors?

I want to see that the AC cord is freed up, so that the
amp can be removed from the cabinet.

Also, there will be a connection from the output transformer
to the speakers.
Post a photo of that.

Use the schematic I posted initially, to
familiarize yourself with the parts using schematic
photos and parts list.

After that's addressed, then you can use the parts list
I posted at the beginning of your topic to order.
Hotwax


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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Thu 12, 2021 10:11 pm 
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Joined: Aug Mon 09, 2021 3:24 pm
Posts: 26
Thank you both! I’ve attached the picture of the output transformer. As you can see, it is connected to the speakers, but also firmly attached to the chassis which therefore keeps it only inches away from the speaker.

I had a quick clarification about the AC cord. Before I was told not to remove the power cord from the outside of the chassis so how should I free the AC cord?

Also, I’ve begin looking at the parts online on Mouser so I have a quick question. In your incredibly helpful explanation, there was not a reference to the resistors. Does that mean I just need to find a metal film resistor (through hole?) resistor with the correct resistance and wattage?

As always, thanks for all the help and let me know if other photos/angles are needed.


Attachments:
File comment: Audio transformer
3D17D7F5-D1CA-4826-993F-FDD6E2A8F1DD.jpeg
3D17D7F5-D1CA-4826-993F-FDD6E2A8F1DD.jpeg [ 473.31 KiB | Viewed 726 times ]
File comment: AC cord inside the chassis
FF294021-4DE5-42C0-9FE8-45E5D0CEE4B3.jpeg
FF294021-4DE5-42C0-9FE8-45E5D0CEE4B3.jpeg [ 487.44 KiB | Viewed 726 times ]
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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Thu 12, 2021 10:37 pm 
Member

Joined: Aug Tue 24, 2010 8:56 pm
Posts: 6195
Location: Northeast Florida
Unless you have a resistor that is visibly charred and burned, I wouldn't worry about replacing those. Even if it drifted way up in value, it's not going to affect the amp to the point where it will no longer work. I would just focus on changing out the paper capacitors

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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Thu 12, 2021 11:13 pm 
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Joined: Jan Wed 16, 2013 12:04 am
Posts: 2541
Location: 77001
Tfkalk wrote:
I’ve attached the picture of the output transformer.
As you can see, it is connected to the speakers, but also firmly attached to the chassis which therefore keeps it only inches away from the speaker.

I had a quick clarification about the AC cord. Before I was told not to remove the power cord from the outside of the chassis so how should I free the AC cord?

1. The two copper leads from the output transformer will need to
be unsoldered from the speaker terminal, when you start the
parts replacement.

2. Power cord. As requested earlier, just take
a photo of it for me.
From the 2 prong end to the chassis, the whole length.

I'm not talking about removing the AC cord from the chassis.
The AC cord on the chassis is permanently attached there.

3. Go ahead and buy the resistors in the parts list.
They are dirt cheap and you might need one.

Any resistor that you match watts and ohms will
work, as long as it has leads for through the hole
soldering. That is correct.

Hotwax


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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Fri 13, 2021 4:36 am 
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Joined: Aug Mon 09, 2021 3:24 pm
Posts: 26
Sorry about that. I’ve attached another picture of the full length of the power cord. It’s quite long! And thanks for the other info!

Also, with the capacitors— C2 and C4 both have no voltage, only “Cap.” What does that mean for finding a replacement?


Attachments:
File comment: Full length of power cord
6305CF49-3FDE-4094-9CE6-E391BFA4DCF0.jpeg
6305CF49-3FDE-4094-9CE6-E391BFA4DCF0.jpeg [ 2.83 MiB | Viewed 712 times ]
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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Fri 13, 2021 4:53 am 
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Joined: Jan Wed 16, 2013 12:04 am
Posts: 2541
Location: 77001
Thanks for the photo. Exactly what I wanted to see.

Where the AC cord is stapled or attached to the
cabinet is another type of strain relief.

You can remove it for working on the amplifier,
but replace it securely when done.

C2 and C4 are referred to as ceramic capacitors, and
are usually very stable.
They do not fail usually, and are not routinely replaced.

On the parts list, you see that these type of caps are
describe as measured in mmfd. This is micro-micro-Farads.

MMFD are equivalent to picofarads in modern use.

Hotwax


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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Sat 14, 2021 12:13 am 
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Joined: Aug Mon 09, 2021 3:24 pm
Posts: 26
Thanks! I went through and found all the items on Mouser (with one exception). I was wondering if you would be able to quickly double-check them to make sure I found the right parts. C8 was the one I was most unsure of for the reason listed below.

- C1A Electrolytic: 82 mF @ 160 Volts https://www.mouser.com/ProductDetail/Nichicon/UCY2C820MPD9?qs=sGAEpiMZZMukHu%252BjC5l7YWnzinYcx146Rm0zrCoRyGI%3D
- C1B Electrolytic: 22 mF @ 160 Volts https://www.mouser.com/ProductDetail/United-Chemi-Con/EMVH161GDA220MLH0S?qs=sGAEpiMZZMukHu%252BjC5l7YbiZfOJBGOHY80oZw8y6PSE%3D
- C2 and C4: Don’t need
- C3, C5, C6: 0.01 mF, but use a 630 Volt rated cap https://www.mouser.com/ProductDetail/KEMET/C4CAWUC3100AA0J?qs=pqRVuuzkf6buGNMNsPxyOw%3D%3D (I went with 630V AC because the power cord is AC, tell me if that’s wrong)
- C7: https://www.newark.com/tdk/c3225x7r2j683k200aa/cap-0-068uf-630v-mlcc-1210-rohs/dp/78AH1699 //not from Mouser, but all of Mouser’s were out of stock
- C8: 0.01 mF X1Y2 capacitor. Using a 250 VAC voltage rating is fine. https://www.mouser.com/ProductDetail/Murata-Electronics/DE2E3SA103MA3BT02F?qs=rrS6PyfT74dJIPo%2FXVEBWA%3D%3D Not sure about this one because the replacement part listed is a cylindrical paper capacitor with wire out both sides and this is a different shape
Resistors
- R3: https://www.mouser.com/ProductDetail/YAGEO/HHV-50FR-52-560K?qs=oypCK0zG325084rLzOgtlw%3D%3D
- R4 and R5: https://www.mouser.com/ProductDetail/Ohmite/OL5655E-R52?qs=sGAEpiMZZMtlubZbdhIBIJMLE6vvLglcd6osrbSQ528%3D
- R6: https://www.mouser.com/ProductDetail/YAGEO/RSF-50JT-52-270K?qs=sGAEpiMZZMsPqMdJzcrNwrSrS5p3UYvS6PsdeCqf1M3mzWdxCzUclQ%3D%3D
- R7: https://www.mouser.com/ProductDetail/KOA-Speer/MF1-2DC4703F?qs=sGAEpiMZZMsPqMdJzcrNws%2FR%2FDeZ6kXccscekzBowdg%3D
- R8: https://www.mouser.com/ProductDetail/TE-Connectivity-Holsworthy/ROX05SJ150R?qs=sGAEpiMZZMsPqMdJzcrNwrSrS5p3UYvSq7J1D%252BUJ0azRgJwbEkD8zg%3D%3D
- R9: https://www.mouser.com/ProductDetail/KOA-Speer/CFS1-2CT26A472J?qs=sGAEpiMZZMsPqMdJzcrNwlGlqEwMEaeo1i5YUFZly5g%3D
- R10: https://www.mouser.com/ProductDetail/KOA-Speer/CF1-2C390J?qs=sGAEpiMZZMsPqMdJzcrNwjhI8IZiJG%252BPIPs2VZWVYDk%3D
- R11: https://www.mouser.com/ProductDetail/Welwyn-Components-TT-Electronics/WP4S-120RJA1?qs=sGAEpiMZZMvNd0dY0KymzqdasCU02b9DYjo1SQMD7YtB71gZuHDqZQ%3D%3D

I ordered the new cartridge/needle from The Voice of America this morning so it should be here in a few days. Thanks as always for your help!


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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Sat 14, 2021 2:02 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 4784
Location: Boston, MA USA
One of the speakers has a large rip in the cone. It can be fixed but will require that the speaker be removed for repair, and removal may be tricky

-David


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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Sun 15, 2021 2:54 pm 
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Joined: Jan Wed 16, 2013 12:04 am
Posts: 2541
Location: 77001
Tfkalk wrote:
Thanks! I went through and found all the items on Mouser (with one exception). I was wondering if you would be able to quickly double-check them to make sure I found the right parts. C8 was the one I was most unsure of for the reason listed below.
I ordered the new cartridge/needle from The Voice of America this morning so it should be here in a few days. Thanks as always for your help!


C3,C5,C6 would be 0.01 mF @ 630 Volts DC .

You selected the 0.1 mF. product with a very high
voltage rating, that is not needed.

Below is the product you want.

https://www.mouser.com/ProductDetail/Co ... vnkGZhE%3D

After the wall AC voltage is rectified and filtered,
the voltage within the audio circuit will be DC voltage.

The vacuum tube filaments run on AC voltage, of no concern to you.

The Murata X1Y2 safety cap is correct, and is in fact
what I have been using.

Nothing you receive will look like the old parts, with
possibly some resistors. Sizes all smaller w/modern ones.

I think you bought your cartridge from The Voice of Music, no ?

Hotwax

p.s. I also saw that speaker tear, but let's finish the amplifier first.


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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Mon 16, 2021 4:23 pm 
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Joined: Aug Mon 09, 2021 3:24 pm
Posts: 26
Yes, I meant Voice of Music, sorry! :oops: And sorry for my delayed response, I didn't get an email notification for some reason. Also, thanks for catching that on the .01 vs .1.

I have all the Mouser parts in my cart, about to order. Unfortunately, the 22mF electrolytic capacitor has since sold out at Mouser. Would this one work then? https://www.newark.com/panasonic/eeued2c220/cap-alu-elec-22uf-160v-radial/dp/62W7566 It has the criteria, but does not look similar to the one I had found from Mouser.

These will take a few days to arrive so obviously I won't be able to do much until then (I will use that time to read up on electronics and soldering). If you have any other suggestions of what I need to buy beyond a simple soldering kit, please let me know.


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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Mon 16, 2021 5:25 pm 
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Joined: Jan Wed 16, 2013 12:04 am
Posts: 2541
Location: 77001
Tfkalk wrote:
I have all the Mouser parts in my cart, about to order.
Unfortunately, the 22mF electrolytic capacitor has since sold out at Mouser.

If you have any other suggestions of what I need to buy beyond a simple soldering kit, please let me know.

1. RE capacitor: Here's a list of available caps at Mouser.
Save you extra shipping from Newark.
Panasonic, Nichicon, CDE/Ilinois all good makers.

https://www.mouser.com/Passive-Componen ... riZ1z0z7l5

2. With the soldering iron, get a tip cleaner holder like this:

https://www.grainger.com/product/HAKKO- ... ner-32TV33

3. Do you have a digital multi-meter ? You may not need it, but
if we need to troubleshoot after the component replacements,
it will be used.
Hotwax


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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Mon 16, 2021 6:23 pm 
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Joined: Aug Mon 09, 2021 3:24 pm
Posts: 26
Okay, thanks! Since I was down to one item on Newark, I searched again for C7 and found this, https://www.mouser.com/ProductDetail/Vishay-Vitramon/VJ1206Y683JXCAT?qs=sGAEpiMZZMsh%252B1woXyUXjw3Ue5uHwYdEb1P1NJW7Rrg%3D. Would this work? It would seem to based off the criteria. I hadn't placed the order yet from this morning so I can get them altogether.

Thanks on the other product recommendations, I'll get them as well!


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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Mon 16, 2021 6:52 pm 
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Joined: Jan Wed 16, 2013 12:04 am
Posts: 2541
Location: 77001
Tfkalk wrote:
Okay, thanks! Since I was down to one item on Newark, I searched again for C7 and found this, https://www.mouser.com/ProductDetail/Vishay-Vitramon/VJ1206Y683JXCAT?qs=sGAEpiMZZMsh%252B1woXyUXjw3Ue5uHwYdEb1P1NJW7Rrg%3D. Would this work?
Thanks on the other product recommendations, I'll get them as well!

Try this instead.
The Vishay doesn't seem to have the appropriate
leads for soldering.
Hotwax

https://www.mouser.com/ProductDetail/Co ... UqDQ%3D%3D


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 Post subject: Re: Zenith ZP-8L Music Very Faint
PostPosted: Aug Mon 16, 2021 11:42 pm 
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Joined: Aug Mon 09, 2021 3:24 pm
Posts: 26
Hotwax wrote:
Try this instead.

Okay, thanks! I placed the order this afternoon so they should be here soon. In the meantime, I did have a question-- the C1A and C1B electrolytic capacitors are in a metal tube. The metal tube goes into the chassis and the wires run from inside the tube to inside the chassis (unlike the amplifier, output, and rectifier which could be unplugged). How do I then change out the parts inside the metal tube? Let me know if any pictures are needed.


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