Unit A

Serial Number:(sticker missing)
Year of Manufacture:1972 (7222 latest component date code)
Date of Receipt:2015 May
Source:JP
State upon Receipt: Grimy dust inside. Stick-on feet missing. Right side of chassis dented and bent. Functional state unknown.
Comment: This is an early AJ-1510 (not the 1510A). The earlier IF board (85-590-1) with IC606 is used.

Date:2015 May
Procedure:
  • Dismantled thoroughly for cleaning.
  • Chassis straightened.
  • Screw-mounted rubber feet installed.
  • Fixed line cord replaced with IEC socket.
  • ICs reseated, one set of molex IC socket pins reseated and resoldered.
  • Some rewiring done on front panel.
  • 2 DR2100 and DR2110 Numitrons have multiple burned-out segments, DR2120 OK. All 4 Numitrons replaced as a set with those from 03611 unit.
  • 3 lamps burned out. Replaced.
  • Noise squelch pot had a broken-off contact. Rewired to use other side, so control action is reversed (CW rotation now lowers the threshold). Need to find 10K pot with shaft of ? diameter.
  • Some touchup done on black anodised aluminum with black marker.
Functional.

Date:2015 May
Symptoms: DC bias of several volts noticed in audio output channel.
Procedure: Tantalum capacitors at output of both audio channels (10uF/20V) replaced (10uF/35V).

Date:2015 Jun
Procedure: Sweep-Speed pot swapped to 03611 unit. New pots installed for Sweep-Speed and Noise-Squelch.

Date:2015 Jun
Symptoms: The design allows 3-digit channels to be entered as 3 digits rather than 4, but operation is requiring entry of an initial 0 - "0881" rather than "881".
Procedure: C207 & logic are intended to provide an additional shift pulse if first digit is 8 or 9. Bad soldering job on C207 (programmer board). Resoldered.

Date:2016 May
Symptoms: Channels in the range 90.1 to 97.9 not working.
Procedure: Display is correct so likely a problem in the preload decoder area producing an incorrect code for the PLL. Bad solder joint on U309.14 (+5V) results in low outputs from gates of U309. Resoldered.

Unit 03611

Serial Number:03611
Year of Manufacture:1976 (7606 latest component date code)
Date of Receipt:2015 May
Source:JP for repair
State upon Receipt: Mildly dusty inside. Fair condition. Hole drilled in front panel for screw to hold broken left mounting post. Functional state unknown.
Comment: This unit is a model AJ-1510A. The later IF board (85-1644-1) which replaces IC606 with discrete components is used.

Date:2015 Jun
Procedure:
  • Cleaned up & some rewiring done.
  • Screw-mounted rubber feet installed.
  • Fixed line cord replaced with IEC socket.
  • ICs reseated.
  • Numitrons swapped to A unit. This unit needs 3 Numitrons.
  • "Unlocked" lamp burned out. Replaced.
  • Throat broken on Sweep-Speed pot (had been overtightened). Replaced with pot from A unit.
  • Some stripped threads on aluminum front panel & door from over-tightened screws. One screw replaced with longer screw & nut.
  • Some touchup done on black anodised aluminum with black marker.
  • Broken left mounting post of front panel glued on. Seems to be holding well but hole still in front panel.
Functional except for bad Numitrons.

Date:2016 Apr
Procedure: Unit returned to Jurgen.


  Unit Log
Heathkit AJ-1510 		bhilpert
2015 May