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Roodpa
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Hi, I know nothing about vintage radios but bought a reconditioned DAC 90 DAC90A bakelite radio  last year for my 'man cave'. I used it every day for a couple of months, listening mostly to Radio Four, and loved it, then one day it just faded out!

A friend of mine who works in electronics,  thought that it may be a valve and told me which one he thought it was. I managed to get one from a guy in Hexham but it did not bring the radio back to life I'm afraid. 

I live in Whitley Bay, near Newcastle upon Tyne, and I need any referrals to someone who can look at it and bring it back to life. Can anyone help please? I would be very grateful.

Moderator Note:

Thread title amended to reflect this radio is a DAC90A and not a DAC90

 

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Topic starter Posted : 17/11/2019 11:19 pm
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Nuvistor
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Welcome to the forum, most of us tend to only repair our own items but someone may be willing to have a look at the DAC90, is it a 90 or a 90A, there are some differences.

I found  this repair shop but its in Doncaster, there are others around but I could only find ones further away, I know nothing about them, just did a web search.

On the whole valves in radios tend to be quite robust unless used outside their specification.

http://www.pasttimesradio.co.uk/index.html

There is one forum member with a radio/tv shop in the NE, he may be able to help but may not be taking work on anymore, let him reply if he wishes so I will not mention his name.

 

 

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Posted : 18/11/2019 12:33 am
sideband
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It's a very common misconception that 'it's a valve'!....and for the record, any valve failing would cause no sound in this set. Where (who) did you buy it from. If they restored it, then most likely they will repair it.

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Posted : 18/11/2019 10:11 am
Till Eulenspiegel
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DAC90, so that's the model with the "red" octal valves.  The valves in these sets are generally reliable, I assume the valve heaters are alight.  It's more likely one of the wax capacitors has failed.  Easy sets to fix.

By the way I'm located not far from Newcastle.

Till Eulenspiegel.

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Posted : 18/11/2019 11:27 am
Roodpa
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@sideband

Hi, thank you for the response. I bought it from a guy on eBay but it's some time ago and I can't find a record of the transaction or messages as they only stay on eBay for a while and are then cleared.

 

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Topic starter Posted : 20/11/2019 1:09 pm
Nuvistor
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See the previous post to yours, I think Till was trying to help.

 

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Posted : 20/11/2019 1:28 pm
Roodpa
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@till

Don't think my previous response sent! Anyway, I bought the radio 'refurbished' a couple of years ago on eBay but, as I said, I know nothing about them. I don't know what red octal valves are so I can't tell you. I have taken some pics and attach them. I hope this helps! The radio lights up now and hums but won't tune to anything (even though the pointer moves across the full spectrum perfectly!).

You said you were close to Newcastle. I'm in Whitley Bay. Would you be willing/able to take a look at it for me? I really don't want to have to start parcelling it up and sending it somewhere hundreds of miles away!

Let me know please.

Bests, Len

DAC 5
DAC 2
DAC 3
DAC 4

 

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Topic starter Posted : 20/11/2019 1:36 pm
Roodpa
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@nuvistor

Thank you Frank. Yes, I've just written back to him and sent some pics. Appreciate your help.

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Topic starter Posted : 20/11/2019 1:37 pm
Nuvistor
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It’s the later A version so no red valves, the red ones are much larger. Nothing wrong with either type.
photo of the earlier red valves.

51B65164 8224 43AF 8816 44B8F581B351

 

 

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Posted : 20/11/2019 1:43 pm
Roodpa
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@nuvistor

I didn't know whether "red" was a brand name or literally red!! LOL!

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Topic starter Posted : 20/11/2019 2:02 pm
Till Eulenspiegel
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Here's another "red" valve. A late production ECH35, if, that is, you can call December 1965 late!

ECH35

Hi Roodpa,

                     Your DAC90A is the later version with the all-glass Mullard valves.  Better than the original DAC90 because of the much lower heat dissipation in the cabinet.

Till Eulenspiegel.

 

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Posted : 20/11/2019 4:13 pm
Terry liked
Roodpa
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@till

Thank you, Till. Here's my earlier post in case you didn't see it. Can you bring it back to life for me? Pretty please?

Bests, Len

Posted by Roodpa

Don't think my previous response sent! Anyway, I bought the radio 'refurbished' a couple of years ago on eBay but, as I said, I know nothing about them. I don't know what red octal valves are so I can't tell you. I have taken some pics and attach them. I hope this helps! The radio lights up now and hums but won't tune to anything (even though the pointer moves across the full spectrum perfectly!).

You said you were close to Newcastle. I'm in Whitley Bay. Would you be willing/able to take a look at it for me? I really don't want to have to start parcelling it up and sending it somewhere hundreds of miles away!

Let me know please.

Bests, Len

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Topic starter Posted : 20/11/2019 5:21 pm
Till Eulenspiegel
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Hi Len,

               I'd be pleased to take a look at the DAC90A.    I'm located in Winlaton, 5 miles from Gateshead and Newcastle.

I attempted to send you a private message through the Forum but "no matches found" for Roodpa.

Checked the Forum directory and Roodpa hasn't been added yet.

Try sending me a PM.

Till Eulenspiegel. 

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Posted : 20/11/2019 6:09 pm
Till Eulenspiegel
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PM successfully sent.

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Posted : 20/11/2019 9:23 pm
Roodpa
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I just want to say a big "Thank You" to Till Eulenspiegel, who got my DAC90A up and running again this morning. It was great to discuss loads of radio stuff about which I knew absolutely nothing (haha) while he fixed my radio but also fabulous to see some magical examples of radios and TVs from the distant past. Lovely guy and SO helpful! Thank you once again!

DAC90A
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Topic starter Posted : 20/12/2019 5:01 pm
Nuvistor
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Good news, glad you are pleased with the result.

 

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Posted : 20/12/2019 6:24 pm
sideband
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So Till, what was the fault?

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Posted : 20/12/2019 9:54 pm
sideband
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@roodpa

If that is your radio in position, can I suggest that you try and get more space at the back of the radio? They get quite hot and need all the ventilation they can get.

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Posted : 20/12/2019 9:57 pm
Till Eulenspiegel
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Len brought the Bush DAC90A this morning and we hoping the set could be fixed without need to leave the set in the shop necessitating a return visit.  It's not much fun driving through traffic this time of year. 

First observations revealed the set had previously serviced in a very competent manner.  Fault symptoms were hum from 'speaker and no radio stations coming in.  The circuit diagram was not to hand but with these circuits you can do a lot without one.   The HT at the cathode of the UY41 HT rectifier read 203 volts, correct.  However, at the other end of the 10Kohm HT smoothing resistor only 45volts.   Should be 95 to 100 volts. What's going on?   Simpson 260 meter  gave a reading of >350Kohms to chassis.  Well, the fault was the UF41 IF amplifier valve gone bad.  Fitted a Marconi branded valve type.W142. That's got the set working again.  The UL41 output valve is working fine and we want to keep it that way.  In the DAC90A the UL41 valve pin 4 tag is used to anchor the control grid components which should quite in order because there is supposed to be no internal connection on that pin. But the UL41 is well known for internal leakages and yet the valve in  Len's set is perfect with none of that nasty staining inside the glass bulb.  Date code April 1952.


Perhaps  valves which were not made by Mullard or Philips might have an internal connection to pin 4.  So to prevent any future problems the 47Kohm grid stopper resistor has been repositioned to the adjacent tag board. See attachment.

Bush DAC90A

 

Noteworthy is the mains connector plug.  A third pin has been added to the connector which means the mains supplied to set is always neutral to chassis.  Never seen that before on one of these sets.    If it was done by the previous repairer, top marks to him. 

It was a pleasure meeting Len and I'm delighted he enjoyed his visit to the shop.

Till Eulenspiegel.

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Posted : 20/12/2019 11:31 pm
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Till Eulenspiegel
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Visit Mike's Bush Radio website to learn more about the company and it's excellent products:

http://www.bushradio.co.uk/

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Posted : 21/12/2019 1:40 am
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